Placement of nasogastric tubes

Date Published:

Theme:

  • Medical devices,
  • Checking

Executive Summary

Background

This investigation examined patient safety issues related to the placement of nasogastric (NG) tubes. NG tubes are passed through the nose, down the back of the throat and through the oesophagus to the stomach. They are used to give medication, fluids, or liquid feed (known as enteral feed) to patients.

Patients may need NG feeding, typically in the short to medium term, because:

  • critical illness or unconsciousness leaves them unable to swallow at all
  • neurological conditions such as stroke leave them at risk of not being able to safely swallow food or drink normally by mouth
  • they have conditions that mean they cannot take in enough food and drink by mouth to meet their nutritional needs.

The placement of an NG tube is checked initially by testing the pH (acidity or alkalinity) of fluid from the stomach that is sucked out of the NG tube using a syringe. This fluid is known as gastric aspirate. The pH tests are conducted using testing strips known as CE marked enteral testing strips for human gastric aspirate. ‘CE marked’ means that the strips have been certified by the manufacturer as meeting European standards. If the aspirate pH is in the ‘safe range’, this indicates that the NG tube is placed correctly in the gastrointestinal tract and can be used to give feed, fluid, or medications. If no aspirate can be obtained, or if the pH of aspirate is not in the ‘safe range’, an X-ray should be undertaken to confirm the position of the NG tube.

A situation where an NG tube is positioned incorrectly, and this is not identified before the tube is used for feed, fluid or medications is a ‘Never Event’. Never Events are defined by NHS Improvement as patient safety incidents that are considered preventable because there is national guidance or safety recommendations that provide strong systemic protective barriers which should have been implemented by healthcare providers.

This investigation used a specific incident of this type of Never Event, referred to in this report as the reference event, as an example to examine the patient safety issues associated with the placement of NG tubes.

The reference event

Fabian, a man aged 26 years, was admitted to an emergency department on 21 December 2018. He had fallen from his bicycle while swerving to avoid a motor vehicle and hit his head on a pavement. At the scene he was observed to be having seizures. Because of this, on arrival at hospital he was placed in an induced coma by an anaesthetic team prior to having a headto-toe CT scan (which uses X-rays and computer technology to create detailed images of the inside of the body). The CT scan showed small intra-cranial bleeds (bleeding within the brain) and a small amount of bleeding around the left kidney. Fabian was transferred to the critical care unit for ongoing care. While an inpatient on the critical care unit, Fabian had a nasogastric (NG) tube inserted. On 22 December 2018 during an attempted weaning from sedation, Fabian became agitated and removed his NG tube. Following further sedation, a new NG tube was inserted to ensure his nutritional needs were met. This NG tube was confirmed as correctly inserted via a pH test of gastric aspirate. It was subsequently found that the NG tube had inadvertently been inserted into Fabian’s lungs and enteral feed had been delivered into his airways. Fabian received approximately 1,450ml of enteral feed into his lungs before the feed was stopped.

Once the misplaced NG tube was identified, the feed was removed from his lung using a special tube with a camera on (known as a bronchoscope). Saline fluid was used to wash out any feed and then syringed back out using the bronchoscope. The incident was immediately reported as a Never Event once the error was realised.

Following a stay on the critical care unit and subsequently on a ward, Fabian was discharged home on 8 January 2019.

National investigation

Data from NHS supply chain shows that each year at least 967,977 NG tubes are purchased in the NHS in hospitals and community settings (care home and home).

NG tubes have been the subject of numerous patient safety alerts in the last 15 years. There is a risk of serious harm and risk to life if NG tubes are incorrectly placed into the lungs rather than the stomach and fluid, medicine or feed is passed through them. Such incidents are classified as a Never Event (NHS Improvement, 2018a).

The safety risk of misplaced NG tubes was referred to the Healthcare Safety Investigation Branch (HSIB) as a potential national investigation due to the persistence of harm despite several patient safety alerts. The referrer reported concerns that both pH testing and use of X-ray are prone to error; these concerns are supported by previous patient safety alerts and literature. The referrer believed that opportunities for error existed for all levels of staff, and that seniority did not necessarily reduce the risk.

A 2016 patient safety alert (NHS Improvement, 2016a) stated that misinterpretation of X-rays by medical staff was the most common cause of placement errors. Other causes included misinterpretation of pH testing of gastric aspirate, use of outdated checking methods, and communication issues between medical and nursing staff to confirm if tube placement was checked.

The HSIB investigation reviewed NG tube insertion and placement verification in the context of local and national practice and guidelines. The national investigation applied a human factors approach to understanding the processes, practices, interactions among people, and other elements of system performance involved with the insertion of NG tubes and confirmation of their position. The investigation considered existing guidance as well as the procurement and implementation of the equipment required for NG tube insertion and confirmation, and how staff acquire the competencies to do this safely. The factors that contributed to the reference event have been grouped under two key processes which were the focus of analysis in this investigation:

1 Confirmation of NG tube placement using pH testing.

2 Interpretation of chest X-rays for clinical deterioration and identification of NG tube position.

Findings

Given the serious and ongoing safety risks, HSIB’s initial national findings were published in an interim bulletin on 5 February 2020 and early safety observations were made. The findings listed below encompass the overall findings of the national investigation, including those from the interim bulletin. The investigation found:

General findings

1 The placement of NG tubes into the lungs rather than the stomach and fluid, medicine or feed being passed through them is defined as a Never Event in the NHS. However, there are no systemic barriers to preventing feeding into an NG tube that has been accidentally placed in the lung.

2 There is ongoing research to find a reliable design solution to reduce the risk of misplaced NG tubes. However, these projects will not be completed for a few years. As such, a new technological solution is not imminent.

3 Local trust policies generally reflect national guidance. However, there are limitations in their use because of their length. Staff told the investigation they know the guidance is there, but such guidance is too long to read.

4 There is significant variation in how existing safety standards are implemented and continually monitored.

5 Reporting NG medical device related incidents to the Medicines and Healthcare products Regulatory Agency (MHRA) via its Yellow Card scheme is less frequently done in comparison to NG tube related incidents reported on the National Reporting and Learning System or Strategic Executive Information System (national systems for reporting patient safety incidents).

6 New ways of working, and specifically extending the role of the radiographer to improve patient safety in NG tube position confirmation, have been effectively implemented and successfully evaluated in some organisations.

7 The introduction of measures to manage COVID-19 resulted in increased challenges for NG tube insertion and confirmation of tube placement.

Findings related to pH testing

8 The process of confirmation of correct NG tube placement using pH testing strips is potentially unreliable and its complexity underestimated. The pH test cannot be used if stomach contents cannot be aspirated and will be inconclusive in patients with altered stomach pH. The investigation also identified concerns around the reliability and usability of pH strips.

9 There is a risk that organisations that insert NG tubes may have multiple types of pH strip in circulation, both CE marked, and non-CE marked.

10 Testing strips are ‘read’ by checking the colour on the strip against a colour chart on the container the strips are kept in. CE marked enteral pH testing strips from different manufacturers have different pH colour coding scales which are inconsistent. If a healthcare provider has more than one type of enteral pH testing strip in circulation at the same time, there is a risk of error when comparing the strips from one product against a container with a different pH scale. Therefore, having two or more types of CE marked strips in circulation could result in inaccurate readings.

11 The multiple types of strip present in the Trust where the reference event took place highlights the need for trusts to have reliable processes in place to implement changes that are required by national guidance – in this case, the removal of non-CE marked pH testing strips for testing human gastric aspirate.

12 There is no standard process on how to read a pH strip. A standard process needs to be defined.

13 Training on NG tube placement is available albeit variable in terms of delivery and content. The cascade model of training (where one group of staff is trained, then each trained staff member trains another group, and so on) has led to some staff ‘teaching’ the incorrect method for testing pH.

14 There is no consistent process for assessing and recording competency in NG tube placement and confirmation using pH testing.

15 There are clinical guidelines on the ‘safe range’ for pH and some trusts use a lower pH due to a perception that a lower pH is safer. Although a range of research has been carried out, there is no consistent research conclusion to guide what the best cut-off pH is to exclude placement in the respiratory tract. There is concern about use of ‘safe range’, and there have been no accredited clinical guidelines or research that would change the ‘safe range’.

16 The environment within which pH testing strips are being interpreted can increase the risk of error. In the reference event, this was particularly noted with the poorly lit environment.

Findings related to X-ray

17 X-ray confirmation of NG tube placement is thought to be the most accurate method if a standard process is consistently followed (Metheny et al, 2019). However, incorrect X-ray confirmation and interpretation is the most common cause of NG tube incidents.

18 There is no consistent process for assessing and recording competency in NG tube placement and confirmation using X-ray. People described different ways of interpreting an X-ray. Even when staff are trained, they may still not follow the algorithm for interpretation and may still not identify NG tube misplacement.

19 All NG tubes are radio-opaque (which means they can be detected on an X-ray). However, it is important that when an X-ray is requested a specific requirement is given. The policy at the reference event Trust and other organisational policies refer to chest X-ray as opposed to NG X-ray. A specific NG X-ray will ensure more visibility below the diaphragm than a standard chest X-ray and therefore the language and choice of image request matters.

20 Whatever the reason for carrying it out, a chest X-ray will enable a clinician to spot incidental findings and is an opportunity to check NG tube position. However, in Fabian’s case, the rationale for chest X-ray was clinical deterioration and the NG tube position was not observed and was not being considered as a causal factor for his clinical deterioration. Therefore, there were missed opportunities in the reference event to identify the misplaced NG tube associated with inattentional blindness (people’s tendency to miss things that are visible because their attention is elsewhere) when interpreting X-rays.

21 There was not a formal radiology interpretation (report) of the X-ray. The responsibility for undertaking a clinical evaluation was delegated to the specialist critical care staff and underpinned by local policy (under the Ionising Radiation (Medical Exposure) Regulations (IR(ME) R) 2017 employer’s procedures). This is not uncommon and is an accepted practice (Care Quality Commission, 2018b).

22 Limited availability and detectability of vital information about NG tube displacement and re-insertion may adversely influence clinical assessment and decision making. This is further confounded by difficulties in the detectability of NG tubes on X-ray, and inattentional blindness when interpreting X-rays.

23 The context within which staff are interpreting X-rays influences their ability to accurately identify abnormalities. This includes factors such as the viewing environment, technical aspects such as display screen resolution, time pressures associated with the software, and the quality of X-ray images.

24 While workload was not a definitive causal factor in the reference event, it is recognised that workload, distractions, and concurrent task requirements will influence staff’s levels of attention. This may mean that protocols for X-ray interpretation are not followed.

25 While it is acknowledged that competency-based training is not a strong systemic barrier to improve safety, there was no standardised competency framework and delivery model for training and assessment in NG tube placement and undertaking placement checks. The potential to use specifically trained experts, such as radiographers, was considered but would need to be trialled. Any training would need to be defined, developed, and tested using a human factors approach prior to any widespread implementation.

HSIB makes the following safety recommendations

Safety recommendation R/2020/106:

It is recommended that Health Education England coordinates the development and publication of a national standardised competency-based training programme for nasogastric tube placement and confirmation by pH testing. The model may include simulation, observed practical assessment and ongoing competency assessment. The competency-based training programme would need to be defined, developed, and tested using a human factors approach prior to any widespread implementation. The competency-based training programme will lead to a recognised accreditation which will be transferable across the NHS care providers in England.

Safety recommendation R/2020/107:

It is recommended that NHS England and NHS Improvement works with the Department of Health and Social Care and others, to identify the process by which the NHS can identify and commission necessary research to support improvements in patient safety. This would include research to confirm nasogastric tube placement.

Safety recommendation R/2020/108:

It is recommended that NHS Supply Chain and the British Standards Institution work together (engaging other system leaders as appropriate, such as the Medicines and Healthcare products Regulatory Agency and NHS England and NHS Improvement), to develop and publish an agreed standard to minimise the risks relating to human errors in the use of pH strips designed for testing human gastric aspirate at the bedside. The standard should consider product design, regulatory standards, procurement practices and human factors engineering to provide a consistent approach that can be embedded within NHS Supply Chain product specifications.

Safety recommendation R/2020/109:

It is recommended that NHS Supply Chain develops essential specifications to support the clinically-led procurement of devices to include devices to confirm nasogastric tube placement, for example, pH testing strips. The essential specifications should set out a range of factors critical to inform the selection by NHS Supply Chain of a product including, but not limited to: clinical output requirements; design and ergonomics; human factors and intended use; and limitations on use and usability. Critically, these specifications should ideally be established in partnership across the healthcare system with clinicians, healthcare professionals and safety leads, while maximising best practice.

While not directly relevant to the reference event, the following safety recommendation has been made given the continued risk of NG tube Never Events following incorrect X-ray interpretation.

Safety recommendation R/2020/110:

It is recommended that the British Society of Gastrointestinal and Abdominal Radiologists, working with Health Education England and the Society and College of Radiographers, develops and publishes a national standardised competency-based training programme for X-ray interpretation to confirm nasogastric tube placement. The competency-based training programme will include the referral process for X-ray to confirm nasogastric tube position and the subsequent reviewing, recording and communication of the clinical evaluation of the X-ray findings prior to initiation of feed. The standards must meet the Ionising Radiation (Medical Exposure) Regulations IR(ME)R requirements. The competency-based training programme will lead to a recognised accreditation for those qualified to clinically evaluate and record their findings, for example doctors, radiographers and advanced care practitioners. The accreditation certificate will be transferable across NHS care providers in England.

HSIB makes the following safety observations

Safety observation O/2020/086:

It would be beneficial if chest X-rays for acutely ill patients were reported by a radiologist, or a radiographer who has undertaken training, to enable them to report on examinations at an appropriate time. The report should include the position of an nasogastric tube if one is present on a chest X-ray.

Safety observation O/2020/087:

It may be beneficial if national organisations including the Medicines and Healthcare products Regulatory Agency, NHS Supply Chain and NHS England and NHS Improvement review arrangements for ensuring all medical device related incidents, Yellow Card reports, or other device safety related information, including any involving concerns with pH or X-ray in the context of nasogastric tubes, are shared between the relevant organisations to inform their respective patient safety responsibilities.

Safety observation O/2020/088:

It would be beneficial for the Department of Health and Social Care to consider post-Brexit arrangements for sharing patient safety incident data with Europe.

Safety observation O/2020/089:

It would be beneficial if the (recommended) national standardised competency-based training programme for nasogastric X-ray interpretation to confirm nasogastric tube placement will be made a contractual and/or regulatory requirement for all healthcare providers to implement and evidence ongoing compliance with.

Safety observation O/2020/090:

It may be beneficial if accreditation for reviewing, recording and communication of the clinical evaluation of the X-ray findings, prior to initiation of feed, is limited to specific staff groups trained in confirming nasogastric tube placement, for example reporting radiographers or radiologists.

Safety observation O/2020/056 (previously shared in interim bulletin):

It is important that organisations are aware that there is not a standard scale/colour scheme across the different manufacturers of CE marked enteral testing strips and they vary in scale (pH of 1-12, 0-6, 2-9 or 3-7). If organisations have CE marked enteral pH testing strips from more than one manufacturer in use at the same time, there is still a potential for error if a pH testing strip is compared against the incorrect box.

Safety observation O/2020/057 (previously shared in interim bulletin):

It is important when transitioning between any types of bedside testing equipment (not just pH strips) the potential for confusion between old and new stock is considered, and the transition managed to reduce that risk and to ensure that staff understand any difference between techniques needed with past and future brands of bedside tests.

HSIB notes the following safety actions

Safety action A/2020/034:

The Trust where the reference event happened, amended the timing of its daily aspirate check from midnight to 10:00 hours.

Safety action A/2020/035:

The Trust where the reference event happened checked the hospital clinical areas to confirm there were no other areas holding non-CE marked pH testing strips for human gastric aspirate.

Safety action A/2020/036:

The Trust where the reference event happened implemented and recorded training and competency assessments for all nursing staff prior to allowing them to insert and confirm placement of nasogastric tubes.

1 Background

1.1 Nasogastric (NG) tubes

1.1.1 NG tubes are passed through the nose down the back of the throat and through the oesophagus to the stomach (see figure 1) and are used to give medication, fluids or liquid feed to patients. NG feeding is typically a short- or mediumterm method of feeding. Patients may need NG feeding because:

  • critical illness or unconsciousness leaves them unable to swallow at all
  • neurological conditions such as stroke leave them at risk of not being able to safely swallow food or drink normally by mouth
  • they have conditions that mean they cannot take in enough food and drink by mouth to meet their nutritional needs.

1.1.2 NHS Supply Chain data suggests that at least 967,977 NG feeding tubes with ENFit connectors (a brand of connector that enables syringes and other devices to be securely attached to NG tubes) were purchased between January 2019 and January 2020 (see table 1).

Fig 1 Route of a correctly inserted nasogastric tube

Table 1 NG feeding tube with ENFit connectors purchased between January 2019 and January 2020
Type of NG tube Number purchased between January 2019 and January 2020
NG feeding tube with ENFit connector 607,327
NG feeding and drainage tube with ENFit connector 360,650

1.1.3 For the purposes of this report, the term NG tube will be used throughout. However, it is recognised that similar safety checks and clinical considerations apply to both orogastric tubes (which are inserted via the mouth rather than the nose) and NG tubes.

1.1.4 NG tubes are inserted by healthcare professionals. The placement of an NG tube is checked initially by testing the pH (acidity or alkalinity) of fluid from the stomach that is sucked out of the NG tube using a syringe. This fluid is known as gastric aspirate. The pH tests are conducted using testing strips known as CE marked enteral testing strips for testing human gastric aspirate. ‘CE marked’ means that the strips have been certified by the manufacturer as meeting European standards. If the aspirate pH is in the ‘safe range’, this indicates that the NG tube is placed correctly in the gastrointestinal tract and can be used to give feed, fluid, or medications. If no aspirate can be obtained, or if the pH of aspirate is not in the ‘safe range’, an X-ray should be undertaken to confirm the position of the NG tube.

1.1.5 The NG tube can enter the trachea (windpipe) instead of the oesophagus during the insertion procedure. If the misplaced tube is not detected before feeding or medications are administered this often results in severe lifethreatening difficulties or death (Metheny et al, 2019).

1.2 National guidance

1.2.1 NG tubes have been the subject of numerous patient safety alerts in the last 15 years, and misplacement of these tubes in the respiratory tract is a ‘Never Event’ (see section 1.4) if it is not detected before starting a feed, or administering fluid or medication (NHS Improvement, 2018b). Table 2 summarises the safety alerts and guidance released in relation to misplacement of NG feeding tubes since 2005.

Table 1 Summary of patient safety alerts and guidance since 2005
Date Title Summary
February 2005 Alert: Reducing the harm caused by misplaced nasogastric feeding tubes (National Patient Safety Agency, 2005a) Alert reported 11 deaths and one case of serious harm due to misplaced NG tubes in a two-year period.
Actions centred on eliminating use of the ‘whoosh test’ (air auscultation); never relying on appearance of aspirate or absence of respiratory distress to confirm placement; replacing the use of litmus paper with the use of pH paper; and, purchasing nasogastric tubes which are radio-opaque (that is, visible on an X-ray) throughout their length. The alert established pH or X-ray as the only acceptable methods of confirming initial NG tube placement.
Supporting materials included information for carers of those who use NG tubes and patients who self-check NG tubes in the community, and decision trees for checking placement in adults and children and babies (not neonates (newborns)), including appropriate testing methods and individual risk assessment.
August 2005 5 Alert: Reducing the harm caused by misplaced naso and orogastric feeding tubes in babies under the care of neonatal units (National Patient Safety Agency, 2005b) Actions were similar to the February 2005 alert but with supporting materials specifically for neonates due to differences in gastric pH.
March 2011 Alert: Reducing the harm caused by misplaced nasogastric feeding tubes in adults, children and infants (National Patient Safety Agency, 2011) The National Reporting and Learning System (NRLS) received a further 21 reports of death and 79 of serious harm due to feeding into lungs as a result of misplaced NG tubes. Most incidents related to misinterpretation of X-rays.
Actions for all providers using NG tubes reinforced aspects of the 2005 alerts, with new actions centred on:
• using the ‘four criteria’ [1] technique for X-ray interpretation and restricting placement confirmation via X-ray to staff assessed as competent in the technique
• restricting nasogastric placement and placement confirmation via pH to staff assessed as competent in the technique, including nil down the tube before initial pH testing
• using only pH test strips CE marked for use on human gastric aspirate
• providing structured documentation formats to reinforce these placement checks
• ongoing audits to monitor compliance.
Various support materials were also provided.
March 2012 Rapid response report: Harm from flushing of nasogastric tubes before confirmation of placement (National Patient Safety Agency, 2012) The National Patient Safety Agency was made aware of two deaths since March 2011 where NG tubes were flushed with water before placement had been confirmed. This gave an inaccurate pH reading that suggested the tube was not in the lungs.
Immediate actions for trusts were to reinforce the ‘never flush’ rule and ensure all staff were aware.
Manufacturers also changed their tube labels that said ‘give 10ml flush to remove guidewire’ to be clear this was after pH testing.
December 2013 Warning alert: Placement devices for nasogastric tube insertion DO NOT replace initial position checks (NHS England, 2013) This alert highlighted two recent incidents involving feed into lungs after an electromagnetic placement device was used instead of pH strips or X-ray to confirm placement, leading to patient deaths.
Actions for all providers were to establish whether electromagnetic placement devices were used locally and to ensure these were never used to confirm placement.
July 2016 Alert: Nasogastric tube misplacement: continuing risk of death and severe harm (NHS Improvement, 2016a) The alert was issued in response to
95 incidents that had been reported
to NRLS and/or the Strategic
Executive Information System (StEIS) since the completion date of the 2011 alert. These incidents involved fluids or medication being introduced to the lungs via a misplaced NG or orogastric tube. Of these incidents, 32 involved patient death.
The most common error type continued to be misinterpretation of X-rays by medical staff, with reports suggesting competency-based training had not been provided and staff were not using the ‘four criteria’ technique.
The alert directed trust boards to undertake an assessment of whether the actions they had recorded as complete after the 2011 alert had been implemented, and if not to introduce them immediately. It required the assessment and any subsequent action plan to be shared with the trust board and published on the trust’s website.

1.3 National Institute for Health and Care Excellence (NICE) guidance

1.3.1 The NICE clinical guideline (updated in 2017) CG32, entitled ‘Oral nutrition support, enteral tube feeding and parenteral nutrition’ (National Institute for Health and Care Excellence, 2006), recommended basic principles to be observed when confirming tube placement:

‘The position of all NG tubes should be confirmed after placement and before each use by aspiration and pH graded paper (with X-ray if necessary) as per the advice from the National Patient Safety Agency and further patient safety alerts. NICE refers to local protocols which should address the clinical criteria that permit enteral tube feeding. These criteria include how to proceed when the ability to make repeat checks of the tube position is limited by the inability to aspirate the tube, or the checking of pH is invalid because of gastric acid suppression.’ (National Institute for Health and Care Excellence, 2006)

1.4 Never Event and incident data

1.4.1 Never Events are patient safety incidents that are considered preventable because national guidance or safety recommendations exist that provide strong systemic protective barriers which should have been implemented by healthcare providers (NHS Improvement, 2018b).

1.4.2 Never Events have the potential to cause significant physical harm, as well as psychological harm to patients, families and staff.

1.4.3 Despite interventions to date, Never Events continue to occur in the NHS, with difficulties in identifying technical solutions to prevent recurrence. Past work has often focused on administrative interventions, increased education and more checks.

1.4.4 Never Events relating to NG tubes are declared when the tube has been misplaced into the respiratory tract and this has not been detected before feeding, flushing, or administering medication.

1.4.5 The strong systemic barriers in the case of misplaced NG tubes are described in the 2016 patient safety alert and resource set (NHS Improvement, 2016a; NHS Improvement 2016b). However, consistent human interactions are required to prevent NG tube incidents occurring.

1.4.6 Table 3 shows the number of incidents of misplaced NG tubes reported to NHS England and NHS Improvement (NHSE/I) since April 2015.

Table 3 Number of reported misplaced nasogastric and orogastric tubes used to administer feed, flush or medication since April 2015
Date range Number of misplaced nasogastric or orogastric tube events reported to NHSE/I
1 April 2015 to 31 March 2016 40 (final data)
1 April 2016 to 31 March 2017 26 (final data)
1 April 2017 to 31 March 2018 22 (final data)
1 April 2018 to 31 March 2019 29 (provisional data)
1 April 2019 to 29 February 2020* 21 (provisional part-year data)
1 April 2020 to 30 September 2020* 14 (provisional part-year data)

* The data is taken from NHSE/I reports as at 23 November 2020 and is continually updated - https://improvement.nhs.uk/resources/never-events-data/

2 Reference events

The investigation used a patient safety incident, referred to as the reference event, as an example to examine issues relating to the placement of nasogastric (NG) tubes.

2.1 Local context

2.1.1 The reference event occurred in a critical care unit at a large acute hospital.

2.1.2 Critically ill patients may need sedation, support for breathing, multiple infusions of medications and fluids, and require complex monitoring. Critically ill patients usually receive one-to-one care from a dedicated nurse.

2.1.3 The patient involved in the reference event required admission to the critical care unit for care of his head injury and support with his breathing.

2.2 Details of the event

21 December 2018

2.2.1 Fabian, a man aged 26 years, was admitted to an emergency department on 21 December 2018 following a fall from his bicycle. Fabian swerved to avoid a motor vehicle and hit his head on a pavement, suffering a head injury. It was observed that Fabian was having seizures at the scene of the accident and when he arrived at the hospital. Because of this, Fabian was placed in an induced coma by an anaesthetic team prior to having a head-totoe CT scan (a scan which uses X-rays and computer technology to create detailed images of the inside of the body). Fabian was transferred to the critical care unit for ongoing care at 20:01 hours.

2.2.2 To ensure Fabian’s nutritional needs were met, a plan was made to insert an NG tube. A nurse inserted the tube on the evening of 21 December 2018. The tube was secured at 61cm at the nose [2]. Tube placement was confirmed by 5ml gastric aspirate with a pH of 2. Aspiration (obtaining a small amount of fluid by suction into a syringe) can be used as a method for confirming safe NG tube placement without the additional need of an X-ray if the pH is within a ‘safe range’ of pH 1 to 5.5 [3]. Therefore, in accordance with guidelines in place at the time, enteral feed was commenced at a rate of 25ml/hour.

2.2.3 On the same evening, Fabian had a catheter inserted into his right internal jugular vein. A chest X-ray was taken thereafter which showed a right sided pneumothorax [4]. A right-sided chest drain was inserted to drain the chest cavity of air.

22 December 2018

2.2.4 At 12:01 hours, Fabian was seen by neurosurgical team staff who confirmed they were happy for Fabian’s sedatives to be reduced. Fabian was seen by a critical care consultant on the daily ward round at 12:30 hours. A plan was made to commence a reduction in sedative infusions to begin the process of weaning Fabian from mechanical ventilation, and to allow assessment of his neurological status.

2.2.5 At approximately 15:45 hours, Fabian became agitated and started reaching for his breathing tube. During this episode, he pulled his NG tube out. His NG feed was stopped.

2.2.6 Following the period of agitation and subsequent removal of his NG tube, Fabian remained on a significant amount of sedation. He was recorded as being ‘deeply sedated’ (RASS -5) [5], apart from at 22:00 hours, when it was recorded in his notes that he was ‘moderately sedated’ (RASS -3).

2.2.7 A senior sister inserted a new NG tube at approximately 17:00 hours. The tube was secured at 57cm at the nose. An aspirate of 2ml was obtained which was recorded as being pH of 3.0. It was therefore considered safe to re-commence feeding.

2.2.8 At 17:08 hours, Fabian’s oxygen requirements increased from 21% to 30%. There was a suspected pulmonary aspiration (accidental inhalation of an object, food or fluid into the windpipe and lungs) on admission, therefore it was not considered unusual for Fabian’s oxygen requirements to increase. Figure 2 shows the gradual increase in Fabian’s oxygen requirements from the point of insertion of the second nasogastric tube, until a chest X-ray was performed showing the nasogastric tube sited in the left lung.

Fig 2 Increase in Fabian’s oxygen requirements

2.2.9 Over the course of the evening and night, Fabian’s respiratory function (his ability to absorb oxygen) gradually deteriorated. Fabian was seen on the critical care consultant evening ward round at 23:56 hours. ‘Mucky brown sputum’ was noted. He was given fluids and continuous monitoring of Fabian’s heart and blood pressure was implemented.

23 December 2018

2.2.10 Fabian had a gastric aspirate check at 04:06 hours and no aspirate was obtained. The tube position at the nostril (57cm) had not changed and Fabian’s feed was calculated, running at 49ml/hour.

2.2.11 At 05:08 hours, Fabian was seen by an ST5 (critical care specialty trainee year 5), who noted that he was exhibiting ‘excessive endo-tracheal secretions’. In addition, over the period of the next few hours, Fabian’s oxygen requirements continued to increase.

2.2.12 Fabian was seen on the critical care consultant ward round at 11:19 hours. The increase in oxygen requirements and cardiovascular support was thought likely to be secondary to a developing chest infection. A chest X-ray to understand the clinical deterioration was performed at 12:12 hours.

2.2.13 The chest X-ray was reviewed by an ST7 (critical care specialty trainee year 7) who documented ‘significant consolidation in left lung, given clinical picture likely Ventilator Acquired Pneumonia (VAP) [6]. Already on tazocin [7]. Sputum and blood culture sent – result awaited’. The misplaced NG tube was not observed. The chest X-ray reviewed by the doctor showed new and significant opacification (a cloudy area as a result of a decrease in the ratio of gas to soft tissue in the lung) of the lower half of the left lung, with the NG tube down the left bronchus and deep into the small airways.

2.2.14 At 16:02 hours the aspirate obtained was blood stained and therefore omeprazole (an antacid that is used to treat and prevent stomach ulcers) was prescribed. Fabian had his right-sided chest drain removed at 16:58 hours by the ST7. Fabian had the volume of fluid remaining in his stomach checked every four hours in line with local policy.

2.2.15 Fabian was later seen at 20:40 hours during the evening critical care consultant ward round. It was documented that he had a ‘Left sided pneumonia’, that is, inflammation of the tissue in the lung usually caused by a bacterial infection. 2.2.16 There was no documented review of the chest X-ray performed earlier that day on the ward round, but the ST7 was present on the round and handed over his earlier findings of a left-sided pneumonia to the evening critical care consultant.

2.2.17 Fabian’s oxygen requirements continued to deteriorate over the next few hours and by 00:00 hours he was requiring 100% oxygen to maintain adequate oxygenation.

24 December 2018

2.2.18 An aspirate was obtained at 00:10 hours and the local policy was followed which included checking the position of the NG tube at the nose. Fabian’s feed continued.

2.2.19 Due to his deteriorating condition, Fabian was seen by an ST5 who prescribed and administered a muscle relaxant to improve the ability of the ventilator to inflate his lungs using appropriate pressures. The ST5 requested the on-call physiotherapy service to see Fabian and noted that he had ‘poor air entry on the left side’ of his chest. The ST5 ordered a chest X-ray to better understand Fabian’s clinical deterioration. This was conducted at 00.29 hours and reviewed at 01.20 hours. The ST5 noted ‘left sided infiltrates’ (the filling of airspaces with fluid, pus, protein or cells in a region of a lung) but did not identify the misplaced NG tube. Fabian’s blood results and increasing oxygen requirements indicated a deteriorating condition.

2.2.20 Later, the ST5 requested that the enteral feed be stopped to help reduce carbon dioxide production, and the feed was turned off at 04:08 hours. At this point, Fabian had received a total of approximately 1,450ml of enteral feed into his lungs.

2.2.21 Fabian was seen on the consultant ward round. The consultant reviewed the chest X-ray taken earlier (at 00:29 hours) and identified the misplaced NG tube on the X-ray. The consultant immediately prepared Fabian for a bronchoscopy (an examination of the airway and lungs using a thin tube-like instrument with a camera at its tip, which can also be used to perform procedures). During the bronchoscopy, the NG tube was seen in the left main bronchus (the passage that conducts air into the lungs) and removed. The feed was also removed from Fabian’s lung via the bronchoscope and a saline washout was performed.

2.2.22 Fabian’s oxygen requirements began to reduce, falling from 100% to 50% over the next 24 hours. The consultant spoke to Fabian’s Father at 17:07 hours and explained what had happened.

Care from 25 December 2018 onwards

2.2.23 On 25 December 2018, Fabian continued to show signs of improvement and the process of weaning from the ventilator and critical care medicines commenced. This continued uneventfully for the next 24 hours until at 19:00 hours on 26 December, when Fabian’s oxygen levels deteriorated. As a result, Fabian was disconnected from the mechanical ventilator and assisted breaths were given via a handheld device. Following this, his oxygen requirements remained high at 80% and a repeat chest X-ray was performed at 20:42 hours. This revealed a large left-sided pneumothorax (a leakage of air into the space between the lung and chest wall, which can cause the lung to collapse). A surgical chest drain was inserted, and it was recorded that approximately 400ml of fluid was drained. The fluid was likely to have been mainly composed of enteral feed as it had a dense appearance when looking at images using ultrasound scan.

2.2.24 Fabian’s oxygen requirements began to return to their previous level following the chest drain insertion. By the morning of the 27 December he was back on 55% oxygen. Fabian continued to receive critical care input and his breathing tube was removed on 1 January 2019. Fabian was discharged to a ward on 4 January 2019 and was discharged home on 8 January 2019.

3 Involvement of the Healthcare Safety Investigation Branch (HSIB)

3.1 Referral of the reference event

3.1.1 Nasogastric (NG) tubes are used to deliver both food and medication to patients. There is a risk of serious harm if tubes are incorrectly placed in the lungs rather than the stomach and this is undetected before they are used for feeding.

3.1.2 HSIB considered this as a potential issue for investigation following an email from a medical registrar who raised concerns about significant harm experienced by patients as a result of misplaced NG tubes.

3.1.3 Placement of NG tubes is confirmed initially by checking the pH of gastric aspirate with CE marked enteral pH test strips. If this aspirate test is unsuccessful, or the pH of the aspirate is not in the ‘safe range’, then an X-ray is undertaken to confirm NG tube placement. The referrer reported concerns that both checks can fail; this is supported by evidence from previous patient safety alerts and literature.

3.1.4 The 2016 patient safety alert (NHS Improvement, 2016a) described that the most common cause of placement errors was misinterpretation of X-rays by medical staff. Other causes included misinterpretation of pH tests by nursing and other staff, use of outdated checking methods, and communication issues between medical and nursing staff to confirm if tube placement was checked.

3.1.5 The referrer believed that these causes highlight that the risk for errors can affect all levels of staff, and that the seniority of the staff involved did not necessarily reduce the risk. The referrer stated concerns about seniority, as several trust responses to the 2016 alert involved restricting X-ray interpretation to consultant-level staff.

3.1.6 HSIB conducted a review of the Strategic Executive Information System (StEIS) and identified a reference event. Following initial investigation, the safety risk was assessed against HSIB’s investigation criteria, which are as follows:

Outcome impact – what was, or is, the impact of the safety issue on people and services across the healthcare system?

Misplacement of NG tubes is a Never Event and incidents reported to StEIS and the National Reporting and Learning System (NRLS) demonstrate that they can lead to severe harm or death. NG tubes are often required in patients who are critically ill, and the harm caused by feed entering the respiratory tract can be particularly severe in this group of vulnerable patients.

Systemic risk – how widespread and how common a safety issue is this across the healthcare system?

Misplacement of NG tubes is a Never Event when the tube has been misplaced into the pleura or respiratory tract and then this has not been detected before feeding, flushing, or administering medication. This type of Never Event persists across the NHS despite numerous patient safety alerts and safety initiatives.

Learning potential – what is the potential for an HSIB investigation to lead to positive changes and improvements to patient safety across the healthcare system?

The Trust investigation of the reference event did not identify a strong systemic barrier to prevent the misplacement of NG tubes. Evidence from the reference event investigation suggested there was potential learning around procurement, elements of pH testing strip design, factors that influence decision making and the current processes for confirming NG tube placement.

3.2 Evidence gathering and methodology

Investigative approach

3.2.1 The investigation considered the healthcare system in its entirety to identify the factors that contributed to the patient safety incident. The investigation was guided by systems engineering principles. These are used to identify and represent the causal flow of events and how these have been influenced by planning, management, and national guidelines.

Investigation team

3.2.2 The HSIB investigation team was multidisciplinary and included:

  • nursing experience
  • systems safety and human factors experience
  • NHS regulatory experience
  • clinical consultant medical staff with experience in quality improvement projects related to nasogastric tube safety.

Reference event investigation

3.2.3 The investigation interviewed Fabian and his Father to establish their experiences of the reference event. The staff at a major trauma centre who were involved in the reference event were interviewed. They included:

  • the clinical director
  • the consultant clinical governance lead
  • intensive care consultants
  • doctors in training
  • nursing staff
  • specialist nurses

National investigation

3.2.4 Following investigation of the reference event, the investigation considered existing guidance on the insertion and confirmation of NG tube placement, and the procurement, use and availability of the equipment required. This included a review of how staff acquire the competencies to do this safely.

Engagement (national investigation)

3.2.5 Stakeholders across the healthcare system were contacted and interviewed to establish their perspective on the national context. They included:

  • NHS England and NHS Improvement National Patient Safety Team
  • the research team at Imperial College London
  • National Confidential Enquiry into Patient Outcome and Death
  • Medicines and Healthcare products Regulatory Agency
  • Department of Health and Social Care
  • British Association for Parenteral and Enteral Nutrition
  • National Nurses Nutrition Group
  • Academic Health Science Networks and Patient Safety Collaboratives
  • NHS Supply Chain
  • Royal College of Radiologists
  • The Society and College of Radiographers
  • Health Education England
  • British Standards Institution
  • NHS healthcare providers
  • Getting It Right First Time. Evidence gathering

3.2.6 Multiple sources of evidence were gathered and reviewed by the investigation, including:

  • Fabian’s medical records
  • interviews with Fabian and his Father
  • relevant local and national policy and guidance
  • relevant incidents reported to StEIS and NRLS
  • fieldnotes from observation visits
  • literature relevant to the identified safety risks.

3.2.7 The evidence gathering process adopted an iterative approach; as further information was gained, additional data sources were identified.

3.2.8 A semi-structured interview plan was developed to gather information on safety risks, and a thematic analysis was performed.

3.2.9 Observations were conducted using a framework for nonparticipant observation, and a thematic analysis was performed on the fieldnotes.

Analysis

3.2.10 The analysis process had the following aims:

  • To generate findings.
  • To develop visualisations of the system involved in the patient’s care pathway and a timeline of the events. This assisted in recognising communications, interactions and decision making.
  • To develop a comprehensive understanding of the healthcare system so that safety recommendations could be identified, and their potential impact on the system could be considered.

3.2.11 These aims were achieved through the application of the following methods:

AcciMap method

3.2.12 The AcciMap model (Svedung and Rasmussen, 2002) was used to analyse the reference event information and support the direction of the national investigation. AcciMap is an incident analysis method that identifies factors within the system that influenced the occurrence of an incident. The analysis focuses on identifying relationships between the different levels of the system (see figure 3), which include government policy and budgeting; regulatory bodies and associations; local area management; physical processes and actor activities (what staff, people, organisations, systems did); and equipment and surroundings (Stanton et al, 2013).

Fig 3 The AcciMap Method (Svedung and Rasmussen, 2002)

Systems Engineering Initiative for Patient Safety

3.2.13 The investigation used a model called Systems Engineering for Patient Safety (SEIPS) (Carayon et al, 2013) to examine the safety factors influencing NG tube insertion and positioning confirmation. SEIPS provides a human factors framework for understanding the work system (that is, the external environment, organisation, internal environment, tools and technology, tasks, and persons), work processes (including physical, cognitive and social/ behavioural aspects) and outcomes in healthcare and the relationships between these. Figure 4 shows the aspects of the work system which were explored as part of this investigation.

Fig 4 Work system factors explored in this investigation

Note: this diagram intends to provide a general overview of the areas explored as part of this investigation. It is recognised that some organisations have either been superseded by another organisation and no longer exist or have been renamed. The areas listed are not exhaustive.

3.2.14 These methods were used to consider local and national practices, and practices evidenced in the literature. This enabled a detailed analysis of how the healthcare system influenced the reference event and allowed potential recommendations for improvement to be considered.

4 Findings and analysis of the management of the patient’s care in relation to national and local contexts

The HSIB investigation reviewed NG tube insertion and placement verification in the context of local and national practice and guidelines. The investigation has identified and described the multiple level interactions of the work system, the processes, and the outcomes associated with the management of Fabian’s care.

The work system factors that contributed to the reference event have been grouped under two key processes which were the focus of analysis in this investigation:

1 Confirmation of NG tube placement using pH testing.

2 Interpretation of chest X-rays for clinical deterioration and identification of NG tube position.

Process 1: confirmation of NG tube placement using pH testing

4.1 Overview

4.1.1 Fabian had removed his first NG tube during a period of agitation. A senior nurse inserted a new NG tube, which was secured using tape. The nurse aspirated approximately 2ml of fluid through the tube. The nurse tested the aspirate on a pH strip which indicated a pH of 3.0. At interview, the nurse confirmed that nothing was flushed down the NG tube prior to the aspirate being obtained. There was no minimum requirement for aspirate required, however, 2ml was sufficient to test the aspirate on a pH strip.

4.1.2 A pH reading of 3.0 confirmed to the nurse that the aspirate was gastric in origin and feeding could be re-commenced. Fabian’s feeding regime commenced in line with policy and in accordance with Fabian’s nutritional needs.

4.1.3 The NG tube was later found to be in Fabian’s respiratory tract. The investigation conducted by the trust at which the reference event took place (referred to in this report as ‘the Trust’) (The Trust, 2019) considered two possible explanations as to how the pH of the aspirate obtained fell within the ‘safe range’ to commence feeding:

  • The respiratory tract sample was acidic. The Trust considered whether the sample collected from Fabian’s respiratory tract was acidic because he had aspirated gastric contents into the bronchial tree (part of the lungs). The Trust concluded that no evidence of cases where this has occurred were found in the literature. Any acidic fluid in the lungs would rapidly disperse into the small airways, making it difficult to obtain an acidic sample. As such this scenario was considered by the Trust investigation team as unlikely.
  • Error in pH testing. The alternative suggestion by the Trust investigation findings was that the incident resulted from ‘human error’ during pH testing. The investigation report referred to a report by NHS Improvement (2016a) which found that errors during pH testing were the second highest cause of Never Events involving NG tubes. The NHS Improvement report went on to say that of the reported errors during pH testing:

‘..none appeared to have been investigated in a way that fully eliminated likely causes of incorrect pH readings (such as a flush to activate lubrication and remove the guidewire, or inappropriate types of pH test strips) but some trusts were sure staff had followed correct procedures and therefore aspirate from the respiratory tract had produced pH reading in the ‘safe range’.’

(NHS Improvement, 2016a)

4.1.4 The HSIB investigation looked at process 1 - the confirmation of NG tube placement using pH testing. The intended goal of the process is to ensure that an NG tube is in the stomach to allow commencement of feeding. The outcome in the reference event was that the NG tube was inadvertently placed in the respiratory tract.

4.1.5 The following sections explore the work system factors associated with this process.

4.2 External environment

National policy and alerts

4.2.1 In 2016, NHS Improvement published a resource set, entitled ‘Initial placement checks for nasogastric and orogastric tubes’ (NHS Improvement, 2016b), to support the associated patient safety alert ‘Nasogastric tube misplacement: continuing risk of death and severe harm’ (NHS Improvement, 2016a). The alert was aimed at trust boards to support exploration of whether they had systems in place to support staff to deliver safety-critical requirements for initial nasogastric and orogastric tube placement. The associated resource set outlined safety-critical requirements for confirming tube position.

4.2.2 In England there are two main types of test for confirmation of NG tube placement: pH strips and X-ray (NHS Improvement, 2016b).

4.2.3 NG tube placement can initially be checked by testing the pH of aspirate (stomach fluid which has been drawn out of the NG tube using a syringe) using pH strips or pH paper. This is typically done by a healthcare professional and is intended to indicate whether the NG tube is in the gastrointestinal tract or, if the test is inconclusive, that it is unclear where the NG tube is placed.

4.2.4 In the national patient safety alert ‘Reducing the harm caused by misplaced nasogastric feeding tubes in adults, children and infants’ (National Patient Safety Agency, 2011), it was mandated that all areas where NG tube placement was likely to occur had access to pH indicator paper that was CE marked and manufactured to test human gastric aspirate.

4.2.5 The pH strip changes colour when an acid or alkaline substance is placed onto it. Gastric secretions are normally acidic, whereas secretions found in the respiratory tract are usually more alkaline. As such, an acidic pH (pH equal to or less than 5.5) would indicate the NG tube is correctly placed in the stomach and it is safe to commence feeding.

4.2.6 In its 2011 alert the National Patient Safety Agency did highlight the potential difficulty experienced by some staff in differentiating pH readings that fell between pH 5 and 6 using (currently) available pH indicator paper. It was therefore recommended that a second competent person checks any readings that fell within the pH range of 5 to 6 (National Patient Safety Agency, 2011).

4.2.7 The NHS Improvement resource (2016b) did advise that ‘no local or national clinical guidance should widen the safe range’. The resource set noted that the ‘safe range’ for excluding respiratory placement may need to be integrated in local guidance with use of different pH ranges for other purposes (for example, tighter pH ranges to distinguish oesophageal from gastric placement). It went on to say that ‘to narrow the current ‘safe range’ of pH, such clinical guidance would be expected to have followed NICE [National Institute for Health and Care Excellence] accredited processes of guidance development, including risk-assessment of the impact of this change of practice’. At the time of writing, no new evidence-based national clinical guidance has been published to narrow the ‘safe range’.

4.2.8 Sometimes no aspirate can be obtained following NG tube insertion, or the pH of the fluid aspirated is not in the ‘safe range’ (particularly when patients are on medication intended to reduce gastric acidity). If the result is not acidic (that is, the pH is greater than 5.5) or is inconclusive, an X-ray is required to check that the NG tube is positioned in the stomach and not in the lungs (National Patient Safety Agency, 2005a; National Patient Safety Agency, 2011).

4.2.9 The National Patient Safety Agency alert (2011) recognised that even in cases of correct NG tube placement, it is possible for the tube to migrate or be dislodged away from the stomach and into the oesophagus or lungs. If this occurs during feeding it could prove fatal. Because of this, the alert referred to additional guidance by the British Association of Parenteral and Enteral Nutrition (BAPEN) which recommended that repeat placement checks (including aspirate pH) were made:

  • before administering each feed
  • before giving medication
  • at least once daily.

4.2.10 Previous Never Events have been linked to dislodgement after correct initial placement (NHS Improvement, 2016b). It is possible that intubation or some forms of respiratory suction could move a previously correctly placed NG tube to the respiratory tract, although reports suggesting this are very rare. The NHS Improvement resource set refers to checking the external tube marking for displacement. However, an unchanged external tube length cannot in itself exclude the possibility of internal displacement (NHS Improvement, 2016b). The guidance highlights that as there are no other definitive safety-critical steps that could be taken, advice on repeat placement checks remains an area for local and professional clinical guidance.

Research regarding reliability of pH testing strips

4.2.11 NHS Improvement (2016b) conducted a review of 95 NG tube incidents reported to the Strategic Executive Information System between 12 September 2011 and 11 March 2016. They found that the second most common type of error involved issues with pH checks (incorrect X-ray interpretation was the most common). Of the 95 incidents, 23 related to pH testing and of these, 15 of the 23 incidents may describe a pH in the ‘safe range’ having been found even though the NG tube was subsequently found to be in the respiratory tract. The limitations of these investigations are referred to in NHS Improvement’s (2016b) review.

4.2.12 Fernandez et al (2010) conducted a systematic review of research into the diagnostic performance of biochemical tests (for example digestive enzymes including bilirubin, pepsin and trypsin) used to determine placement of NG tubes after insertion in adults. Of the 10 studies included in the review, seven investigated the diagnostic accuracy of pH, one investigated the diagnostic accuracy of pH and bilirubin respectively, two a combination of pH and bilirubin and one a combination of pH, pepsin and trypsin levels in identifying NG tube position. Bilirubin coupled with pH demonstrated the ability of the test to identify misplaced tubes in the intestine. However, the ability of the test to correctly identify gastric placement of feeding tubes was relatively low. The review was critical of the evidence available and so was unable to draw conclusions about the diagnostic performance of the different tests.

4.2.13 Work conducted for the NHS Patient Safety Research Portfolio in 2010 (Hanna et al, 2010) recommended changing the cut-off from a pH of 5.5 to a pH of equal to or less than 4.0 to verify gastric position. Patients with pH between 4.0 and 5.5 were recommended to have an assessment of risk. For a pH of 5.5 or higher, feeding should only start if an X-ray had confirmed stomach placement. One reason provided for this recommendation was the variety of pH papers in use at that time, some of which were not accurate enough and had potential for underestimating pH.

4.2.14 A more recent study highlighted that the pH testing of gastric aspirate can be associated with false positive and false negative readings. There was often disagreement between observers when pH readings were borderline (Rowat et al, 2018).

4.2.15 In a review of guidelines associated with NG tube insertion (Metheny et al, 2019), it was concluded that pH testing of NG aspirate was the most favoured non-radiological method for checking NG tube position. However, there was a lack of consensus on the best pH cut-off point; values of pH 4.0, 5.0, and 5.5 were cited in the guidelines (Metheny et al, 2019). The investigation was also informed of variation in the best cut-off point for pH and in some cases were told that X-ray was the mandated first-line check.

4.2.16 Some organisations in England have narrowed the ‘safe range’ and included this in their own local policy with a rationale as to why, for example:

‘…therefore by working to a pH of 5 we are increasing patient safety and the confidence of those checking the position of a tube that it is safely placed. Brands of pH testing strips that make it difficult to see any colour change between readings so again by setting 5 as our acceptable pH level we remove the need for a clinical judgement and can have greater confidence that at a pH 5 our NG tube is in the correct place and it is safe to feed.’

(Saddington, 2018)

The investigation reviewed other hospital policies and found that some trusts have used a pH of 4.0 as their cut-off ‘safe range’.

4.2.17 A small survey undertaken by BAPEN found six cases where a pH of equal to or less than 5.5 led to feeding and a Never Event. BAPEN reported that it could not be sure whether the protocols for reading pH were followed or not, but the alternative explanation was that the tube was sited in aspirated gastric contents within the lungs. BAPEN emphasised that an acid pH only shows the aspirate is acid, not where it was derived from. The question of obtaining an acid pH from a lung aspirate was also considered by the investigation, which included discussion with representatives of BAPEN who shared that while this is possible, there was no evidence to back this up (Personal communication, BAPEN, 13 July 2020).

National guidance for education around NG tube position checks

4.2.18 NHS Improvement’s resource set (2016b) highlighted that in its review of incidents, X-ray and pH testing had often been carried out by staff who had not received competency-based training, and therefore did not follow the safety-critical requirements. The resource states that:

‘Staff training, competency frameworks and supervision are reviewed to ensure that all healthcare professionals involved with nasogastric tube position checks have been assessed as competent. Competency training should include theoretical and practical learning.’

(NHS Improvement, 2016b)

4.2.19 In May 2018 the Nursing and Midwifery Council (NMC) published new standards of proficiency for registered nurses, which describe the knowledge and skills nurses need to be able to join the NMC register (Nursing and Midwifery Council, 2018a). It also published new education and training standards for nurses, midwives and nursing associates (Nursing and Midwifery Council, 2018b). These are the standards that set out how the standards of proficiency should be taught. Contained within the standards for proficiency is to ‘insert, manage and remove oral/nasal/ gastric tubes’ (Nursing and Midwifery Council, 2018a). The investigation was not able to confirm if all registered nurses have acquired a recognised certificate of competency that would include confirmation of NG tube position at the point of completion of their training. In addition, there is no national standardised ongoing assessment of competency post qualification.

4.2.20 After qualifying, registered nurses are expected to maintain their competence through regular learning and professional development activities as described in the NMC code (Nursing and Midwifery Council, 2015), and for revalidation (Nursing and Midwifery Council, 2019).

4.2.21 Organisations establish their own training and competency assessments for insertion and confirmation of placement of NG tubes. For revalidation, nurses must demonstrate they are reflecting and maintaining continuing professional development (CPD) in relation to their scope of practice and this would include competency in NG tube placement and confirmation if it is essential to their role. Where specialisation requires particular knowledge or skills (for example NG tube insertion in critical care), the standard required in practice should reflect this requirement. The NMC expectation is that organisations supporting nurses to meet CPD requirements for revalidation should consider the new proficiencies when discussing with nurses how they can develop their skills and knowledge.

4.2.22 While competency-based training is not a strong systemic barrier to improving safety, it is currently the one that is most relied upon by many organisations. The investigation found that there is no standardised competency framework and delivery model for training and assessment in NG tube placement and undertaking pH checks. As such, there is scope for variation in the content and quality of NG tube placement and confirmation check training.

4.2.23 Approaches to competency-based training and assessment are varied. Some organisations attempt to train and assess all staff who insert and confirm NG tubes. Others have a more targeted approach to competency-based training and assessment of NG tube confirmation. The targeted and more restrictive approach was in most cases related to X-ray confirmation only, although the investigation observed that some organisations do include confirmation by pH testing.

4.2.24 In a simulated study, Borsci et al (2017) found a 11.15% error rate in participants’ readings of pH strips, with important implications for decision making regarding NG tube placement. The researchers stated:

‘The lack of usability of pH strips, and the lack of formal training in performing the multi-tasks required for decision making may be causes of error. The finding that there was no difference between the errors made by both clinicians and non-clinicians in reading the strips suggest a need of pH strip redesign.’

(Borsci et al, 2017)

Availability of pH strips

4.2.25 The NHS Improvement resource set ‘Initial placement checks for nasogastric and orogastic tubes’ describes that:

‘Other incident investigations found a range of pH paper, not all CE marked, was in use in different clinical departments in an organisation.’

(NHS Improvement, 2016b)

This implies that trusts may not only have the risk of using non-CE marked strips, but may have multiple types of strip in circulation. See section 4.3.9 for an explanation of CE marking.

4.2.26 The HSIB investigation found that CE marked pH strips have different pH colour coding scales depending on which manufacturer made them. (See appendix A).

4.2.27 If a trust has pH strips from more than one manufacturer, there is a risk of comparing a pH strip from one manufacturer against the colour chart on a container from another manufacturer with a different pH scale. Therefore, having two or more CE marked strips in circulation could result in inaccurate readings.

4.2.28 The investigation did not establish if and how many organisations were aware of the risks associated with having various types of pH strip, however, HSIB made the two following safety observations in its interim bulletin (Healthcare Safety Investigation Branch, 2020), which remain relevant.

HSIB makes the following safety observations

Safety observation O/2020/056 (previously shared in interim bulletin):

It is important that organisations are aware that there is not a standard scale/colour scheme across the different manufacturers of CE marked enteral testing strips and they vary in scale (pH of 1-12, 0-6, 2-9 or 3-7). If organisations have CE marked enteral pH testing strips from more than one manufacturer in use at the same time, there is still a potential for error if a pH testing strip is compared against the incorrect box.

Safety observation O/2020/057 (previously shared in interim bulletin):

It is important when transitioning between any types of bedside testing equipment (not just pH strips) the potential for confusion between old and new stock is considered, and the transition managed to reduce that risk and to ensure that staff understand any difference between techniques needed with past and future brands of bedside tests.

4.3 Organisation Local NG tube policies and guidelines

4.3.1 There were two applicable local policies for the staff involved in the reference event to follow. There was a Trustwide policy for the safe insertion and management of NG tubes (The Trust, 2018a) and a specific guideline for initiating NG feeding in critical care (The Trust, 2018b). There was also a supplementary Trust-wide policy for initiation of NG feeding although this excluded critical care (The Trust, 2015). The policies were all accessible via the Trust intranet and were in date at the time of the reference event.

Local Trust-wide NG tube policy

4.3.2 The Trust-wide policy covered the insertion of all NG tubes. All supplementary policies which discussed NG tube insertion or confirmation referred to this overarching policy. The policy was 22 pages long and included flowcharts for staff to follow. The investigation identified that the Trust’s policy was in line with recommended national guidance.

4.3.3 Staff told the investigation they knew the policies existed but that they were too long to read.

4.3.4 The Trust’s policy instructed staff to ‘test aspirate using CE marked paper/strips’. A pH of 5.5 or below confirmed gastric placement, and feeding could commence. The policy directed the person inserting the NG tube to ‘record the marker of length of the NG tube at the nose (this should usually be within 54-60 centimetres)’. If confirmation of placement could not be achieved by a test of gastric aspirate pH, the policy outlined alternative steps to follow to confirm NG tube placement.

Local critical care NG tube guideline

4.3.5 The Trust’s critical care unit had a specific guideline (The Trust, 2018b) for initiating and early monitoring of NG feeding. The guideline was designed to allow for safe and appropriate initiation of enteral tube feeding within 24 hours of a patient’s admission to the critical care unit. The critical care guideline referred directly to the Trust-wide NG tube insertion policy (The Trust, 2018a). The critical care guideline included those patients in which NG feeding should be avoided or given cautiously. The guideline did not replace discussion with senior clinicians as required.

4.3.6 Patients in the Trust’s site’s critical care unit were fed over 24 hours, with a very short pause in feeding once a day to re-test the tube position. The critical care policy had a flowchart checklist for this confirmation of existing NG tube position. Staff were directed ‘at midnight every 24 hours minimum, [to] check and record the pH’ (see figure 5).

Fig 5 Confirmation of existing NG tube position checklist (The Trust, 2018b)

Confirmation of existing NG tube position checklist - refer to Insertion of NG tube for newly inserted NG tubes

At midnight every 24 hours minimum, check and record the pH. If pH >5.5 or no aspirate follow flow diagram below

4.3.7 The investigation observed that the Trust’s 24-hourly pH testing was conducted at midnight when there was the potential that staff were less alert than daytime hours and when there were fewer senior staff available. The Trust considered that midnight was not appropriate and changed its 24-hour check to 10:00 hours.

HSIB notes the following safety action

Safety action A/2020/034:

The Trust where the reference event happened, amended the timing of its daily aspirate check from midnight to 10:00 hours.

Procurement of pH paper

4.3.8 Following insertion of Fabian’s second NG tube, the nurse aspirated approximately 2ml of fluid from the tube. The nurse tested the aspirate on a pH strip which indicated a pH of 3.0. The pH reading of 3.0 confirmed to the nurse that the aspirate was gastric in origin and feeding could be re-commenced. It is likely a non-CE marked pH strip was used.

4.3.9 Nationally there was a requirement for trusts to revise their purchasing policies relating to pH strips (NHS Improvement, 2016b; National Patient Safety Agency, 2011). Trusts were required to systematically remove old stock to ensure all pH test strips were CE marked, and that they had been manufactured to test human gastric aspirate. This was because some pH papers were designed specifically for laboratory testing and so were not appropriate for testing human gastric aspirate. This was reinforced in 2016 in the self-assessment included in the NHS Improvement resource pack. The self-assessment questions were not a formal assurance framework or audit tool, but were designed to assist trust boards (or their equivalent in other organisations providing NHS-funded care) and their commissioners to challenge themselves in relation to the implementation of safety-critical actions.

4.3.10 The Trust’s investigation found that its critical care unit was using both non-CE marked and CE marked pH testing strips. The non-CE marked pH testing strips were not specifically designed for gastric sample testing. The use of two different types of pH strip could have been a possible cause of an incorrect pH reading. This investigation finding by the Trust in 2019 is consistent with the NHS Improvement review of investigations of misplaced NG tubes between 2011 and 2016, which identified that incident investigations found a range of pH paper, not all CE marked, was in use in different clinical departments in an organisation (NHS Improvement, 2016b).

4.3.11 In November 2018, the Trust had switched from non-CE marked pH strips (0 to 6.0 range), to CE marked enteral pH strips (2.0 to 9.0 range). The Trust found there were gaps in its transition from non-CE marked to CE marked pH testing strips in line with previous national guidance.

4.3.12 The two types of pH testing strips at the Trust had different pH scales and used different colour coding schemes to represent the pH level (see figure 6). If the non-CE marked strip was exposed to a neutral substance such as a respiratory tract sample, and then inadvertently read against the CE marked enteral pH testing strip scale, it would read as strongly acidic, falling in the 2.0 to 3.0 range. A pH of 2.0 to 3.0 would indicate that the NG tube was correctly placed in the stomach.

Fig 6 A difference in colour coding between non-CE marked and CE marked pH testing strips in use at the time the reference event occurred.

A non-CE marked pH strip exposed to a neutral respiratory tract sample when checked against the colour chart on a CE marked testing strip container reads as pH 2.0/2.5.

HSIB notes the following safety action

Safety action A/2020/035:

The Trust where the reference event happened checked the hospital clinical areas to confirm there were no other areas holding non-CE marked pH testing strips for human gastric aspirate.

Local NG tube training

4.3.13 A standardised process for NG tube training and competency assessments for the insertion and confirmation of NG tube placement were in place at the Trust and reflected the safety-critical requirements in the resource set (NHS Improvement, 2016b). However, they were not consistently applied by all Trust staff. Staff told the investigation they had received training in NG tube placement and confirmation. Evidence of competency assessments were not kept.

4.3.14 At the Trust, the practical elements of training for NG tube confirmation tasks, for example, how to conduct pH testing, had been implemented using a cascade training approach.

4.3.15 Cascade training is an inexpensive way to rapidly disseminate knowledge and training by getting initial trainees to then train groups of staff, who in turn may then train another group (Gask et al, 2019). However, there is a risk that training quality can decay when using a cascade training approach (Gureje et al, 2015). Information can be diluted, or key messages misinterpreted as the information passes from one trainer to the next. As such, there was scope for variation in technique and practice for NG tube confirmation checks.

4.3.16 Indeed, the investigation observed a nurse who had been taught by another colleague to incorrectly interpret a pH strip. When the nurse was asked to describe how they interpreted the pH, they described the method incorrectly, describing the technique used for interpreting pH on a urinalysis testing strip instead. The nurse was only comparing one colour instead of all three colours on the pH strip to determine pH. As such, the nurse was inaccurately interpreting the pH reading.

4.3.17 The above observation was shared verbally with the National Nutrition Nurses Group and the group’s Chair stated she had heard of and witnessed very similar examples of reading pH strips in this way.

4.3.18 There were limitations in how competencies among staff were tracked and monitored at the Trust. The Trust told the investigation that it did not have records of nursing staff competency for confirming NG tube placement using pH testing. An immediate safety action was implemented to ensure that nursing staff were competent prior to allowing them to insert and confirm placement of NG tubes.

HSIB notes the following safety action

Safety action A/2020/036:

The Trust where the reference event happened implemented and recorded training and competency assessments for all nursing staff prior to allowing them to insert and confirm placement of nasogastric tubes.

Local critical care acuity and workload

4.3.19 The critical care unit at the Trust had 27 beds across four areas. At the time of the incident, the unit was commissioned for 16 level 3 beds and 11 level 2 beds [8]. The level of care assigned to a patient would influence, but not determine, staffing requirements.

4.3.20 On 21 December 2018 at the time of Fabian’s admission, the acuity in the unit was high, with 19 level 3 patients and 5 level 2 patients.

4.3.21 Fabian required sedation, multiple infusions of medications and fluids, and complex monitoring. As such, he was receiving one-to-one care while on the critical care unit and was classified as a level 3 patient.

4.3.22 According to national standards, level 3 patients must have a registered nurse/patient ratio of a minimum of 1:1 to deliver direct care (The Faculty of Intensive Care Medicine and Intensive Care Society, 2019).

4.3.23 In critical care units, there must be a supernumerary senior registered nurse (that is, a senior registered nurse not rostered to deliver direct patient care to a specific patient) who provides the supervisory clinical co-ordinator role on duty 24 hours a day, seven days a week (Francis, 2013). As the Trust’s unit had between 21 and 30 beds, it should have additional supernumerary senior registered nursing staff over and above the supervisory clinical coordinator to enable the delivery of safe care.

4.3.24 The nurse caring for Fabian was also the senior nurse in charge and care co-ordinator for a six-bedded bay. This meant the nurse was required to supervise three colleagues and provide one-to-one care for Fabian. While the nurse deemed their nursing demands were manageable and not excessive, it was not normal practice to be the senior nurse in charge and have an allocated patient.

4.3.25 At the time Fabian removed his own NG tube, the senior nurse was providing clinical advice to the nurse in an adjacent bed space, which was a routine part of the co-ordinator’s role. Therefore, the senior nurse was not directly with Fabian. Another nurse saw Fabian suddenly become agitated and shouted for help.

4.3.26 At interview, all Trust staff described a challenging working environment but said that despite the high acuity, there were enough nursing staff to meet the need. The senior nurse reported that they did not think that the workload on the shift played a significant role in this incident. Although the Trust nursing staff did not perceive the workload on the day to be a factor, the investigation could not rule it out. This is because there was evidence of distractions and concurrent task requirements, meaning that Fabian’s care was not the sole focus of staff’s attention. High workload is a stressor which can result in negative cognitive effects such as distraction and narrowing of attention (Salas and Driskell, 2016).

4.4 Tasks NG tube insertion

4.4.1 NG tube insertion is a skilled task that, according to the Trust’s policy, should only be carried out by experienced and competency assessed healthcare professionals (The Trust, 2018a).

4.4.2 When healthcare professionals insert an NG tube, they are unable to see whether the NG tube is being correctly placed into the stomach. Staff may believe they will see some signs of distress or coughing if the tube is misplaced, but many reports of tube misplacements indicate that the positioning of the tube incorrectly into the airway and lung caused no signs or symptoms at all.

4.4.3 The nurse who inserted Fabian’s new NG tube after the original tube had become dislodged reported that Fabian had coughed while the new tube was being inserted. The nurse had paused the NG tube insertion and continued to insert the tube once he had finished coughing. The nurse commented that it was a small cough which they did not perceive as significant. They were also aware that they would be checking the placement of the NG tube afterwards by pH testing the aspirate.

Reliability and usability of pH testing

4.4.4 During an observational visit to the Trust, the investigation found that the process of pH testing could be unreliable. There was also reported confusion about when to test pH aspirate once a feed has commenced. A nurse reported, and the investigation observed, that stomach aspirate drawn once feeding had commenced could have a pH of 5.5 or above.

4.4.5 The investigation found research that identified another reported case of false-positive pH aspirate, thought to be related to the effect of an advanced head and neck cancer (Sellers, 2012). National and professional guidance (National Patient Safety Agency, 2011) does not recommend the use of pH testing for patients with known neck or chest anatomical issues.

4.4.6 Stomach pH can be altered by the use of some medications, for example, acid-supressing medications. Very little data exists on how medication affects the pH of the stomach (other than acid suppression medication), so it is not possible to obtain this from medicine information sheets or other clinical evidence. Other additional factors that can affect the stomach pH include the feed itself, 24-hour feeding, and infection. The limitations of obtaining an accurate pH reading in these circumstances is also reflected in national guidance.

4.4.7 Borsci et al (2017) reported that professionals underestimate the complexity of using pH strips to ascertain the position of an NG tube. The process of positioning and checking the tube using pH strips is a multi-task process with various points requiring decision making. The usability and experience of the use of pH strips among professionals was considered poor (Borsci et al, 2017). Misinterpretation of the colour of pH strips has also been reported to be common (Taylor and Clemente, 2005). In both studies, the researchers challenge the idea that pH testing is an appropriate firstline check.

4.5 Person

Patient

4.5.1 Fabian was actively being weaned from his sedation following review by the neurologist at 12:52 hours on 22 December 2018. Fabian pulled his NG tube out at 15:45 hours. This was the first time he had suddenly woken up. The Trust reported that it would have been very difficult to predict that the transition from deep sedation to agitation would occur so rapidly. Staff told the investigation that the amount of time it takes to wean a patient off sedatives depends on a variety of factors. These include the patient’s presenting clinical condition, the type of sedation, the length of time they have been under sedation, and other factors.

4.5.2 Fabian was unconscious at the time the original and second NG tube was inserted.

Staff

4.5.3 The senior nurse who inserted Fabian’s second NG tube, reported that at the time they were not aware that there were two types of pH testing strips with different pH scales in circulation. This highlights a risk associated with implementation of new equipment and devices.

4.6 Internal environment

pH strip storage

4.6.1 The Trust’s critical care unit had an ‘enteral feeding cupboard’ which contained all the required equipment for enteral feeding.

4.6.2 The Trust investigation team found that boxes of pH testing strips, both CE marked and nonCE marked, were kept together in a basket in the enteral feeding cupboard. The pH strips were very similar in appearance. As such, it was possible that in the reference event, the strip was compared to the colour chart on the wrong container and gave false reassurance that the NG tube was correctly placed.

Critical care environment

4.6.3 Fabian was being cared for within a critical care unit at a large acute hospital. It was not a modern facility and had not been specifically designed for its purpose.

4.6.4 The Trust’s policy for safe insertion and management of NG tubes (The Trust, 2018a) stated that pH paper should be interpreted immediately in a well-lit area. The HSIB investigation observed that the Trust’s critical care unit had no natural light, and the lighting levels were variable throughout the department with some areas of the department being particularly dark. The investigation observed one nurse moving around their patient’s bed space, holding a pH testing strip in an area with greater light levels to accurately interpret the testing strip.

4.6.5 The investigation also observed nurses using torches to aid their vision. The dark environment could have impacted staff members’ ability to correctly interpret pH testing strips.

4.6.6 The unit was crowded with equipment trollies, it was described as noisy, and there were well-known risks associated with the layout of the unit which had been escalated to the risk register. Robust plans were in place for a redesigned critical care unit. The staff were observed to be working well within these limitations and had a shared mental model of the risks and the actions necessary to minimise them.

Critical care bed spaces

4.6.7 The investigation observed that the nurse went to the drawer of the patient bedside workstation to get the pH testing strip.

4.6.8 Each patient bed space contained a movable bedside workstation in which was stored equipment the nurses required for routine bedside tasks. The investigation observed that there was no consistency in terms of the equipment each bedside workstation contained or the location in which the equipment was stored.

4.6.9 The investigation observed that equipment could be placed together in the same drawer with no compartmentalisation, requiring staff to search to find an item they required.

4.6.10 Nurses commented that they could configure their bedside workstation to suit their personal preferences.

4.6.11 Limitations in the organisation and consistency of bedside workstations increases the likelihood that staff may not find the equipment they require or select the wrong item.

Summary of process 1: confirmation of NG tube placement using pH testing

1 The process of confirmation of correct NG tube placement using pH testing strips is potentially unreliable and its complexity underestimated. The pH test cannot be used if stomach contents cannot be aspirated and will be inconclusive in patients with altered stomach pH. The investigation also identified concerns about the reliability and usability of pH strips.

2 There is a risk that organisations that insert NG tubes may have multiple types of pH testing strips in circulation, both CE marked, and non-CE marked.

3 Testing strips are ‘read’ by checking the colour on the strip against a colour chart on the container the strips are kept in. CE marked enteral pH testing strips from different manufacturers have different pH colour coding scales which are inconsistent. If a healthcare provider has more than one type of enteral pH testing strip in circulation at the same time, there is a risk of error when comparing the strips from one product against a container with a different pH scale. Therefore, having two or more types of CE marked strips in circulation could result in inaccurate readings.

4 The multiple types of strip present in the Trust where the reference event took place highlights the need for trusts to have reliable processes in place to implement changes that are required by national guidance – in this case, the removal of nonCE marked pH testing strips for testing human gastric aspirate.

5 There is no standard process on how to read a pH strip. A standard process needs to be defined.

6 Training for NG placement is available albeit variable in terms of delivery and content. The cascade model of training (where one group of staff is trained, then each trained staff member trains another group, and so on) has led to some staff ‘teaching’ the incorrect method of testing pH.

7 There is no consistent process for assessing and recording competency in NG tube placement and confirmation using pH testing.

8 There are clinical guidelines on the ‘safe range’ for pH and some trusts use a lower pH due to a perception that a lower pH is safer. Although a range of research has been carried out, there is no consistent research conclusion to guide what the best cut-off pH is to exclude placement in the respiratory tract. There is concern about use of ‘safe range’, and there have been no accredited clinical guidelines or research that would change the ‘safe range’.

9 The environment within which pH testing strips are being interpreted can increase the risk of error. In the reference event, this was particularly noted with the poorly lit environment.

HSIB makes the following safety recommendations

Safety recommendation R/2020/106:

It is recommended that Health Education England coordinates the development and publication of a national standardised competency-based training programme for nasogastric tube placement and confirmation by pH testing. The model may include simulation, observed practical assessment and ongoing competency assessment. The competency-based training programme would need to be defined, developed, and tested using a human factors approach prior to any widespread implementation. The competency-based training programme will lead to a recognised accreditation which will be transferable across the NHS care providers in England.

Process 2: interpretation of chest X-rays for clinical deterioration and identification of NG tube position

4.7 Overview

4.7.1 Shortly after Fabian’s second NG tube was inserted and feeding commenced, his condition worsened.

4.7.2 Fabian’s clinical deterioration prompted a series of assessments by critical care staff, including ordering chest X-rays on 23 and 24 December. The two chest X-rays showed the misplaced NG tube. However, the specialty doctors in training ST5 and ST7 who reviewed the chest X-rays did not notice the incorrect placement of the NG tube. They therefore did not correctly establish the cause of Fabian’s deterioration. It is important to note that the ST5 and ST7 were not checking the chest X-ray for NG tube position. The X-rays were not reported on by a radiologist, which was normal practice for the critical care unit at the time of the incident.

4.7.3 At 10:56 hours on 24 December, a consultant who had not previously been involved in Fabian’s care reviewed the most recent chest X-ray. The consultant saw the NG tube in the lung and ordered a bronchoscopy. Fabian’s NG tube was placed deeply into the lung tissue and into the small airways where gas exchange occurs (see figure 7).

Fig 7 Fabian’s chest X-ray showing the NG tube sited into the left lung

4.7.4 The Trust highlighted in its own internal investigation that the image of the tube placement was important for two reasons:

  • ‘It makes it extremely unlikely that the NG tube would have been able to migrate into this position once the introducing wire had been removed after the first aspirate was obtained.
  • The depth of insertion when measured on the chest radiograph [X-ray] appears to correspond with a level which would leave the NG tube at exactly 57cm at the nose.’ (The Trust, 2019).

4.7.5 The Trust investigation concluded that it appeared certain that the NG tube seen in Fabian’s lungs on the chest X-ray from 23 December was the one that had been inserted at 17:00 hours the previous day by the senior nurse. The Trust investigation reported that there were no further documented episodes of significant agitation which could have resulted in tube misplacement or migration. There were also no further attempts to re-site the NG tube in the period of time between the NG tube being inserted at 17:00 hours on 22 December and the chest X-ray being taken at 12:12 hours the following day (23 December).

4.7.6 The process of interest to HSIB’s investigation is the ‘interpretation of chest X-rays for clinical deterioration’. The intended goal of the process is to identify abnormalities on the X-ray that might support diagnosis of the cause of clinical deterioration. The outcome in the reference event was that the specialty doctors did not identify that the NG tube was misplaced; however, they were not reviewing the X-ray specifically for NG tube placement. This process also allows exploration of how X-rays are used to confirm placement of NG tubes.

4.7.7 The following sections will explore the work system factors associated with the process of interest.

4.8 External environment

National policy and alerts

4.8.1 There is a significant amount of legislation that determines how X-rays are performed, who can refer a patient for an X-ray, who can interpret an X-ray for clinical decision making and who can formally report on an X-ray (Department of Health and Social Care, 2018; Department of Health and Social Care, 2017; Royal College of Nursing, General Chiropractic Council, General Osteopathic Council, Chartered Society of Physiotherapy, NHS Alliance, The Royal College of Radiologists and Society and College of Radiographers, 2008). Appendix B is a summary of the relevant legislation and subsequent guidance.

4.8.2 The responsibility for how the legislative and regulatory guidance is implemented rests predominantly with local trusts.

4.8.3 The resource set ‘Initial placement checks for nasogastric and orogastric tubes’ (NHS Improvement, 2016b) states that X-ray can be used to confirm NG tube placement but is not recommended for routine use in all patients. Testing the pH of aspirate can be used as a first-line method for confirming safe NG tube placement. X-ray would be required if aspirate pH in the ‘safe range’ (pH 1.0 to 5.5) could not be obtained, and for patients where confirmation of optimum gastric placement was necessary. X-ray may be required in other specific scenarios and such cases should be preceded by robust assessment.

4.8.4 The NHS Improvement guidance (2016b) also highlights that X-ray request forms should clearly state if the purpose of the X-ray is to establish NG tube position. This is to ensure that radiologists and radiographers interpret the X-ray using the ‘four criteria’ for gastric placement of NG tubes. In addition, stating the purpose, for example for NG tube placement confirmation, ensures that the image is adequate for an NG tube check as it will show more visibility below the diaphragm than a standard chest X-ray.

4.8.5 Interpretation of the X-ray for NG tube placement would typically be done by certain medical staff, trained radiographers or by radiologists.

4.8.6 In a review of guidelines associated with NG tube insertion (Metheny et al, 2019), it was found that X-ray, when properly performed and interpreted, was the most accurate method for confirming NG tube placement. X-ray was generally supported for high-risk patients, for example, for those who were critically ill or had an altered level of consciousness or a diminished or absent gag reflex. However, X-rays cost more and caused delays in commencing feeding and inconvenience for patients and staff, as well as exposing patients to radiation.

4.8.7 The investigation identified variability in interpretation of when to use X-ray and that local policies differ.

4.8.8 The NHS Improvement review of NG tube incidents reported to the Strategic Executive Information System (StEIS) between 12 September 2011 and 11 March 2016 (NHS Improvement, 2016b) found that incorrect X-ray confirmation was the most common cause of NG tube incidents.

National guidance for education around NG tube position checks

4.8.9 There is a national requirement to ensure that all healthcare professionals involved with NG tube position checks have been assessed as competent through theoretical and practical training (National Patient Safety Agency, 2011).

4.8.10 The resource set produced by NHS Improvement (2016b) recognised that not all trusts had created ongoing training programmes, or levels of training completion had not been routinely monitored and had lapsed. They found that training may be perceived by trusts as unnecessary for experienced or senior staff. Alternatively, trusts may perceive that newly registered nursing staff and junior doctors must already have had their competencies assessed during their training.

4.8.11 The NHS Improvement resource set (2016b) summarised the safety-critical requirements for confirming initial NG tube placement. It highlighted that competency-based training needed to reflect all the safety-critical requirements summarised in the resource set.

4.8.12 The resource set stated that training for X-ray interpretation of NG tube placement should include ensuring that the X-ray viewed is the most current, ensuring the four criteria approach for confirming gastric placement is implemented, and providing clear instruction and communication whether it was ‘safe to feed’. It also recommended having structured documentation to assist recall of this process and associated training.

4.8.13 The investigation reports and data that informed the resource set were recognised by NHS Improvement to have limitations. Data was obtained from National Reporting and Learning System reports and StEIS, where the information provided varied from a short description to several hundred words summarising the investigation. As such, some detail may have been missing.

4.8.14 Trust investigations are also known to have limitations (NHS Improvement, 2016b; Toft, 2015). A review into the quality of trust investigation reports (Care Quality Commission, 2016) found that nearly 75% contained unanswered questions or unexplained issues, leaving the focus on staff acts or omissions. Too often the investigation reports identified the causal factors as staff failing to follow trust policy and procedures. The lack of a systems approach to these investigations meant recommendations were focused on staff, such as reminding them to follow policy and procedure, and to conduct further training. The Care Quality Commission review highlighted that retraining staff was not always the right solution.

4.8.15 Many of the findings described in the NHS Improvement review (2016b) which were related to X-ray interpretation highlighted training as a key factor. However, it is possible that owing to limitations in the quality of investigations reviewed, the wider system factors associated with X-ray interpretation were not explored. As such, there may be an overemphasis on training as a mitigation for reducing errors in X-ray interpretation.

4.8.16 In 2016 a trust undertook a system-wide evaluation of its practice in relation to the placement and confirmation of NG tubes (Earley, 2019). The evaluation identified several issues, including that 90% of advanced nurse practitioners and doctors who were involved in confirming NG tube position using X-ray had received no specific training. The trust found there were a lot of resources to support education and training, but there was a gap in how to assess competency, particularly for using X-ray to confirm NG tube placement.

4.8.17 The trust designed an e-learning package which was co-designed with clinical staff and relatives of a patient who had experienced an NG tube related Never Event. The e-learning package reflected the safety-critical requirements highlighted by NHS Improvement (2016b), there was an assessment function as part of the package, and it was made mandatory for all staff to complete.

4.8.18 As part of the e-learning package, a five-point approach was developed using the mnemonic NEX, 2Cs and 2Ds to highlight the required areas to review on an X-ray to check NG tube placement. The mnemonic prompted staff to review the measurement between different parts of the anatomy: from the Nose to Ear to Xyphoid process (NEX), then the anatomical landmarks Carina and Clavicle (2Cs), and finally the Diaphragm and Deviation (2Ds). A standardised approach to documenting the findings and rigorous audit and reporting were also reported to have been implemented.

4.8.19 This initiative won the patient safety improvement category in the 2018 Nursing Times Awards. Health Education England adopted the e-learning package as part of its educational platform. Evidence from a formal evaluation of the e-learning tool demonstrated a statistically significant improvement in the workforce’s capability (Earley, 2019).

4.8.20 The investigation was told of another trust’s approach to competency-based training following two Never Events due to misinterpretation of NG tube position on X-ray. The trust has developed an online platform which delivers teaching and assessment for individuals who review X-rays for correct positioning of NG tubes (RAIQC, 2020). The platform includes teaching slides explaining what the correct positioning should be, followed by 30 training cases where users review diagnostic-quality imaging and make a judgment about whether it is safe for the patient to be fed. They are required to review all 30 cases correctly before receiving a competency certificate. This can be exported to their e-portfolio as evidence of training completion. Since the implementation of this training tool, there have been no NG tube related Never Events at the trust. The investigation was told that other hospitals had used the training and that with the support of the Oxford Academic Health Science Network, the training will be implemented across the Thames Valley region.

4.8.21 Despite the above examples of initiatives to improve staff competence, training in England is not standardised and is not combined with a broad array of changes, such as equipment, organisation, supervision, teamwork and the application of human factors principles to these changes (Leape et al, 2002).

4.9 Organisation

Local policy for X-ray interpretation of NG tubes

4.9.1 The Trust’s policy for the safe insertion and management of a NG tube outlined how medical staff should assess NG tube position when interpreting a ‘chest X-ray’. The Trust policy referred to chest X-ray or CXR and did not specifically state NG X-ray:

‘The chest X-ray must be reviewed within two hours to avoid delays in feeding, by competency assessed personnel who have undertaken the e-learning package on NGT confirmation using CXR via the Trust blended learning system.’

The policy highlighted that a chest X-ray must be performed and viewed by a doctor/ nutritional nurse specialist and the result of the X-ray documented.

4.9.2 The Trust policy stated that

‘…the position of the tube should be documented in the medical notes prior to it being used, using either the ‘NGT position assessment using chest X-ray’ stickers, or if using free text in electronic systems, minimum data must include:

  • correct patient i.e., patients name, hospital number and ward
  • correct chest x-ray i.e. patients X-ray number
  • date and time it was taken
  • who reviewed it
  • assessment of position using the 2C’s and 2D’s approach (clavicle, carina, diaphragm and deviation)
  • if correctly positioned, documented that it is safe to use
  • if not correctly positioned, then the action required i.e., remove, reposition and re-test or advice sought if unclear.’

4.9.3 The Trust had created a chest X-ray proforma to aid X-ray interpretation. However, staff reported that this was not always used. Reasons given were that the proforma was relatively new and some staff continued with their more familiar ways of working.

4.9.4 In Fabian’s case, an X-ray to confirm his NG tube position had not been required as the gastric aspirate obtained fell within the ‘safe range’.

Local education and training

4.9.5 The Trust followed the Health Education England e-learning package described in paragraphs 4.8.17 and 4.8.18.

4.9.6 Both the ST5 and ST7 who were involved in Fabian’s care reported having completed the Trust’s e-learning package. They described the process for reviewing NG tube placement using chest X-ray, although neither described the ‘NEX, 2Cs, 2Ds’ mnemonic precisely. It was reported that there were also numerous systems that doctors could use for general X-ray interpretation (when the purpose of the X-ray is not for confirming NG tube placement). It was reported that staff used whichever system they found easiest to remember.

4.9.7 The investigation found that although the Trust had resources available to support nurses’ and doctors’ education and training, there were limitations in how to assess competency for confirming NG tube placement. The competency assessment following the e-learning package guided participants through the required checks but did not always assess staff performing the task itself.

4.9.8 There were also limitations in how competencies among staff were tracked and monitored at the Trust.

4.9.9 All the staff involved in Fabian’s care told the investigation they had been trained in confirming NG tube placement using pH testing or X-ray through the Trust’s e-learning package.

4.10 Tasks

Interpretation of chest X-rays for NG tubes

4.10.1 While the most accurate method for confirming correct NG tube placement is X-ray, there have been multiple reports of X-rays being misinterpreted by clinicians leading to patient harm.

4.10.2 The limitations of using X-ray to confirm NG tube placement include:

  • exposure to radiation
  • unsustainable demand on X-ray equipment leading to delays in feeding
  • the delay in waiting for a feed to commence due to clinician availability to interpret X-ray
  • the potential for misinterpretation
  • accessibility issues for those people requiring NG feeding in the community
  • increased hospital moves of seriously ill patients between wards and departments.

4.10.3 Interpretation of X-rays requires an understanding of background information and context. In the reference event:

  • The ST7 reported that doctors did not routinely insert NG tubes. The responsibility for NG tube insertion, following protocols for tube placement and the management of the NG tube, belonged with nursing staff.
  • The ST5 and ST7 doctors who were caring for Fabian overnight on 22 and 23 December 2018, reported that they were not aware that Fabian had removed his initial NG tube and that a new one had been re-sited at 17:00 hours on 22 December 2018.
  • Nursing staff were required to document NG tube insertion, changes, and the checks they had performed. However, the investigation reviewed a hard copy printout of the electronic medical records and found that the records only referred to the initial NG tube insertion. The investigation was told if information was not uploaded to the electronic patient record system correctly, for example, new NG tube insertion dates, then the latest NG tube insertion date may not be displayed.
  • The ST7 reported that in their mind, Fabian had been on enteral feed for two to three days and so the NG tube did not form part of his decision making for causes of clinical deterioration.

4.10.4 Interpretation of X-rays is also influenced by perceived and actual time pressures and competing demands. In the reference event:

  • Both the ST7 and the ST5 who reviewed Fabian’s chest X-ray reported that the unit was busy, and staff were experiencing time pressure when reviewing the chest X-rays.
  • The ST7 reported that it was not unusual for doctors to take short-cuts when looking for an abnormality in a chest X-ray because of feeling rushed. They reported that there was a process for reviewing an X-ray, but they did not use this process when reviewing Fabian’s chest X-ray.
  • The ST5 reported that they had been caring for another very ill patient who they had needed to spend a lot of his time with, and had occasionally checked on Fabian. When they reviewed Fabian’s chest X-ray, they reported: “I was needed at the bedside of another unwell critical care patient so there was an element of time pressure when reviewing the chest X-ray.” The ST5 stated that they felt rushed in their review of Fabian’s chest X-ray and did not use their usual, more rigorous, process when reviewing it.
  • There was an additional opportunity for a consultant to have reviewed Fabian’s chest X-ray during the evening ward round. However, the ward round was described to be busy with interruptions and so the consultant only heard the ST7’s report of their chest X-ray findings.

4.10.5 When a patient has an X-ray, a radiologist, or a radiographer who has undertaken training to enable them to report on examinations, will usually report on the images. The radiology report will summarise the findings and may make recommendations such as the need for further investigations.

4.10.6 The Trust stated in its policy that radiographers could be used to confirm NG tube placement via X-ray, however, this was more on an elective basis and generally it would be done by doctors or radiologists.

4.10.7 The chest X-rays taken in response to Fabian’s clinical deterioration were not reported on by a radiologist or a radiographer. They were reviewed by the referring doctors involved in Fabian’s care and treatment. The investigation was told by staff that this is not uncommon in critical care.

4.10.8 When an image is described as having been ‘reported’ it means the radiologist or radiographer has finalised the report. It may be sent immediately by electronic means or take additional time if manual processes are used (Healthcare Safety Investigation Branch, 2019). The investigation was told that nationally there has been an increase in radiographs not being reported by radiology/ radiography staff, with reporting instead being delegated to local clinical staff. This is not uncommon (Care Quality Commission, 2018b). However, staff undertaking formal clinical evaluation must be adequately trained and entitled to perform this task as mandated by the Ionising Radiation (Medical Exposure) Regulations 2017 (IR(ME)R) (Department of Health and Social Care, 2017). It is possible that, as has been described by the doctors involved in Fabian’s care, people look for an answer to the question they have about the patient rather than undertaking a systematic assessment of the image, which is what radiologists and reporting radiographers are trained to do (The Royal College of Radiologists, 2018).

4.11 Person

Patient

4.11.1 The investigation observed that several tubes and lines could be seen on Fabian’s chest X-ray, only one of which is the NG tube (see figure 7). As such, the NG tube looks like other lines that normally would be seen in an X-ray for a patient in critical care.

Staff: inattentional blindness

4.11.2 It was likely that both doctors who looked at Fabian’s X-ray’ were influenced by ‘inattentional blindness’ when reviewing the chest X-rays. Inattentional blindness is a failure to see visible objects we may be looking at directly when our attention is elsewhere (Mack, 2003).

4.11.3 When the medical staff ordered the first chest X-ray for Fabian on 23 December 2018, the rationale for ordering the X-ray was to identify whether a chest infection was causing his condition to deteriorate. When the ST7 reviewed the chest X-ray at 12:58 hours, they noted what they considered to be pneumonia on the left-hand side of the lung. The ST7 made this assessment based on a history of aspiration of stomach contents at the time of the accident, which increased the risk of an infection presenting in the lung. The pneumonia fitted with their clinical assessment of Fabian’s deterioration. At interview, the ST7 stated, “you see what your mind wants to see”. Similar reports have been found in the literature and include expert observers (Drew et al, 2013) which also means expert observers also have made these types of error.

4.11.4 A further chest X-ray was undertaken at 00:29 hours on 24 December 2018, due to Fabian’s continuing clinical deterioration. A chest drain, which had been inserted to treat Fabian’s collapsed lung (pneumothorax) on the right side of his chest, had been removed earlier in the day. The ST5 doctor caring for Fabian was concerned that a re-accumulation of the pneumothorax could be the cause of the deterioration in his respiratory function. The X-ray was reviewed by the ST5; however, they also did not notice the misplaced NG tube. The ST5 told the investigation this was a “failure in X-ray interpretation… my mental model was consolidation”. They had mainly been focused on the right-hand side of the chest, and not where the NG tube was located (in the left lung).

4.11.5 The X-ray also showed an area of ‘clouding’ which was interpreted as pneumonia, which reduced the contrast between the NG tube and the area of accumulation making the misplaced NG tube more difficult to detect.

4.11.6 Both doctors were focused on clinical theories for Fabian’s deterioration that did not involve the NG tube. They were not directing their attention to the position of NG tube on the chest X-ray, and instead were looking for signs of infection or of a collapsed lung. When attention is focused on one object or task, it can be at the expense of noticing and attending to other available information (Mack, 2003).

Staff: fatigue

4.11.7 The length of shifts for both doctors and nurses at the Trust varied between 8 hours and 14 hours 15 minutes. Apart from one long day shift, night shifts tended to be the longest on average at 10 hours 45 minutes for nurses and 12 hours 30 minutes for doctors.

4.11.8 A conversation with a consultant revealed that in addition to a night shift, there may be additional tasks, activities, and commitments to be completed during daytime hours prior to the start of the night shift. As such, staff may have had limited rest prior to starting a long shift.

4.11.9 The investigation found that staff seemed to have a limited understanding of fatigue risks and how best to manage them. Senior staff reported that when designing a shift pattern, they considered staff perceptions, wellbeing, and work/life balance. While it is good that staff perceptions and wellbeing were being considered, the potential impact of the shift pattern on patient safety and on the likelihood of errors occurring did not seem to be a factor in the design of the shift patterns.

4.11.10 Some of the decisions and actions that occurred during Fabian’s care took place towards the end of a 12-hour shift, or at times of day when staff’s levels of alertness were likely to be reduced. For example, the second chest X-ray was reviewed at 01:20 hours. This is a time during which people naturally enter a ‘window of circadian low’ where overall performance and cognitive functioning are at their worst (Monk, 1988). The ‘window of circadian low’ is usually between the hours of 02:00 hours and 05:59 hours (Burban and Jackson, 2017). As such, the investigation was unable to rule out fatigue as a possible contributory factor in this incident.

4.11.11 Fatigue can have a detrimental effect on performance and increase the likelihood of human error. Wagstaff and Sigstad Lie (2011) conducted a systematic review of the literature on the effects of work hours on various health outcomes, safety and performance. The review found that work periods of eight hours and above carry an increased risk of an accident, and that the risk cumulates. Therefore, the risk of an accident at 12 hours is twice the risk at eight hours. The review found that shift patterns that included night shifts carried a substantial increased risk.

Circadian rhythm

There are numerous daily circadian (biological) rhythms such as blood pressure, body temperature, hormone levels and the sleep/wake cycle which oscillate over a 24-hour cycle

(Ishida et al, 1999).

4.12 Tools and technology

X-ray imaging software

4.12.1 At the Trust, X-ray images were reviewed on desktop computers and laptops within the critical care unit. The ST7 reported that these computers were not ideal as they could be slow to load the images.

4.12.2 The investigation observed that it took approximately 32 seconds for an X-ray image to load on a desktop computer in the trainee doctors’ office when the patient’s electronic record was already open. The investigation did not observe how long it took to load an X-ray image on a mobile laptop, but it was reported that this could be slower.

4.12.3 During its observation of the critical care unit, the investigation witnessed a discussion between medical staff which prompted a specialist doctor in training to review an X-ray on a mobile laptop to confirm NG tube placement. The doctor did not use the proforma which the Trust had developed for the NG tube check and had difficulties adjusting the contrast on the X-ray image to improve visibility of the NG tube. Importantly, this was a chest X-ray and not an NG X-ray. The investigation observed the consultant showing the doctor how to change the contrast.

4.12.4 A discussion with a junior doctor at the Trust revealed they were meant to review general chest X-rays on a high-resolution computer, but that did not always happen. The rationale given by staff at the time was that this was because of time pressures as it was quicker to look at X-rays on a laptop at the patient’s bedside.

4.12.5 The investigation concluded that the time delays in X-ray image loading would exacerbate the perceived time pressure doctors were experiencing. In addition, limitations in X-ray image quality and the capability to improve contrast may result in detail, such as a misplaced NG tube, being more difficult to see.

4.12.6 The investigation understands that the Trust’s radiology department has display screens and equipment which are better suited for displaying and thus interpreting X-ray images. National guidance by the Royal College of Radiologists describes standards for diagnostic display screen equipment that allows for optimised viewing of images (The Royal College of Radiologists, 2019a). However, it was reported that radiologists or a reporting radiographer did not typically interpret the critical care unit’s X-rays unless it was specifically requested. Radiographers are trained to identify and act upon unexpected and urgent findings even if not reporting radiographers (The Society and College of Radiographers, 2020).

Electronic patient records

4.12.7 The investigation identified that the way in which case notes were displayed on the Trust’s electronic patient record system may have made it difficult to identify key events such as NG tube displacement and re-insertion. The case notes were displayed as a long list, and so a record of the NG tube displacement and re-insertion may not have stood out and could have been missed.

4.12.8 The printout of events from an electronic patient record system does not enable easy retrospective review of key events and decision making. This had an impact on the investigation when analysing the electronic patient records. 4.13 Internal environment X-ray interpretation environment

4.13.1 The ST7 doctor reported that interpreting an X-ray in the critical care unit environment was not ideal due to the distractions it presented. They reported that there would be other things going on around them, such as alarms sounding and staff conducting other tasks.

4.13.2 A consultant at the Trust reported that ideally X-ray images should be interpreted in a quieter environment where distractions were minimised. There was a small doctors’ office which was accessible for staff if needed.

HSIB makes the following safety observation

Safety observation O/2020/086:

It would be beneficial if chest X-rays for acutely ill patients were reported by a radiologist, or a radiographer who has undertaken training, to enable them to report on examinations at an appropriate time. The report should include the position of an Nasogastric tube if one is present on a chest X-ray.

Summary of process 2: interpretation of chest X-rays for clinical deterioration and identification of NG tube position

1 X-ray confirmation of NG tube placement is thought to be the most accurate method if a standard process is consistently followed (Metheny et al, 2019). However, incorrect X-ray confirmation and interpretation is the most common cause of NG tube incidents.

2 There is no consistent process for assessing and recording competency in NG tube placement and confirmation using X-ray. People described different ways of interpreting an X-ray. Even when staff are trained, they may still not follow the algorithm for interpretation and may still not identify NG tube misplacement.

3 All NG tubes are radio-opaque (which means they can be detected on an X-ray). However, it is important that when an X-ray is requested a specific requirement is given. The policy at the reference event Trust and other organisational policies refer to chest X-ray as opposed to NG X-ray. A specific NG X-ray will ensure more visibility below the diaphragm than a standard chest X-ray and therefore the language and choice of image request matters.

4 Whatever the reason for carrying it out, a chest X-ray will enable a clinician to spot incidental findings and is an opportunity to check NG tube position. However, in Fabian’s case, the rationale for chest X-ray was clinical deterioration and the NG tube position was not observed and was not being considered as a causal factor for his clinical deterioration. Therefore, there were missed opportunities in the reference event to identify the misplaced NG tube associated with inattentional blindness (people’s tendency to miss things that are visible because their attention is elsewhere) when interpreting X-rays.

5 There was not a formal radiology interpretation (report) of the X-ray. The responsibility for undertaking a clinical evaluation was delegated to the specialist critical care staff and underpinned by local policy (under the Ionising Radiation (Medical Exposure) Regulations (IR(ME)R) 2017 employer’s procedures). This is not uncommon and is an accepted practice (Care Quality Commission, 2018b).

6 Limited availability and detectability of vital information about NG tube displacement and re-insertion may adversely influence clinical assessment and decision making. This is further confounded by difficulties in the detectability of NG tubes on X-ray, and inattentional blindness when interpreting X-rays.

7 The context within which staff interpret X-rays influences their ability to accurately identify abnormalities. This includes factors such as the viewing environment, technical aspects such as display screen resolution, time pressures associated with the software, and the quality of X-ray images.

8 While workload was not a definitive causal factor in the reference event, it is recognised that workload, distractions, and concurrent task requirements will influence staff’s levels of attention. This may mean that protocols for X-ray interpretation are not followed.

9 While it is acknowledged that competency-based training is not a strong systemic barrier to improve safety, there was no standardised competency framework and delivery model for training and assessment in NG tube placement and undertaking placement checks. The potential to use specifically trained experts, such as radiographers, was considered but would need to be trialled. Any training would need to be defined, developed, and tested using a human factors approach prior to any widespread implementation.

5 National focus

5.1 Safety culture/behavioural factors

5.1.1 The reference event is not an isolated incident and misplaced nasogastric (NG) tubes continue to result in serious harm and death, despite safety alerts, guidelines, and resources to prevent Never Events. The former National Patient Safety Agency (NPSA) guidance stated that NHS trusts must comply with guidelines to prevent future Never Events.

5.1.2 People have shared their concerns that the safety culture and level of rigour applied to the insertion of NG tubes is not on a par with other interventions to support nutrition, for example feed administered through a vein, otherwise known as total parenteral nutrition (TPN). The President of the British Association of Parenteral and Enteral Nutrition shared his thoughts that this is a serious problem within our hospitals.

5.1.3 The investigation was made aware of a behavioural change approach to the implementation of NG tube placement patient safety guidance by the Bradford Institute for Health Research. The report headlines are below (Taylor et al, 2013).

  • This safety improvement project aimed to use an individual-level behaviour change approach to support the implementation of the NPSA alert to reduce the risk of feeding into misplaced NG feeding tubes by working with staff to encourage the use of pH as the first-line method for checking tube position.
  • A significant effect was found whereby the pH method was more likely to be used post intervention (71.1%) than pre intervention (11.6%). X-ray as a first-line method was less likely to be used post intervention (8.9%) than pre intervention (74.4%, x2 = 44.72, p < .001).
  • This project demonstrates the potential for a behavioural change approach for the effective implementation of national guidelines in an NHS trust.

5.1.4 The NPSA safety alerts discuss steps that may reduce the potential for errors involving NG tubes. These include, for example, competencybased training for staff interpreting X-rays or testing the pH of aspirate, using CE marked pH paper intended for gastric secretions, and never inserting any substance down the tube prior to confirming initial placement. An NPSA review of local investigations suggested problems with organisational processes for implementing alerts. They also suggested there may be increased risks from NG tube placement or X-ray checking at night.

5.1.5 A study by Taylor et al (2013) focused on supporting the implementation of the NPSA evidence-based guidance including identifying local barriers and circumstances that affect behaviour change. The guidance at the centre of the study recommended the first-line method of checking pH level and only to use X-ray if the pH is above 5.5. There were differences in the key barriers reported among the three organisations included in the study, and the paper supported the value of considering local context and local expertise in the design of interventions and implementation of guidance.

5.1.6 NHS Improvement developed a resource set (NHS Improvement, 2016b) to support the NHS Improvement patient safety alert ‘Nasogastric tube misplacement: risk of death and severe harm through failure to implement previous guidance’ (NHS Improvement, 2016a). The alert required trust boards, and their equivalents in other providers of NHS-funded care, to challenge themselves and examine how fully previous guidance on NG tubes had been implemented and embedded in their organisations. The resource set provided a selfassessment tool which could be used by organisations for local reflection (NHS Improvement, 2016a). However, the alert highlighted gaps where guidance could be strengthened and highlighted gaps in evidence requiring further research. There is limited information as to what trusts did at a local level following the alert and resource pack.

5.1.7 The Care Quality Commission (CQC) (2018a) has reported on the challenges of complex alert implementation, which included NG tubes.

5.1.8 The HSIB investigation has attempted to add to previous work on NG tube safety by considering the NG tube placement issue in relation to a whole (sociotechnical) system. For example, providing an understanding of the interactions between different components and factors, such as:

  • patient-specific factors
  • staff – fatigue, experience, tradeoffs, familiarity with different pH scales
  • equipment/tool – different types of pH testing strip in use
  • organisation – workforce, different staff involved, communication
  • task – delayed feedback on placement
  • environment – distractions.

5.1.9 Clinicians told the investigation that they did not always adhere to NG tube guidance. Rationale for not adhering to guidance was explained with some describing taking short cuts, having to make quick decisions, and a lack of confidence in the first-line testing using pH. When explaining why they might undertake certain procedures which are not in line with national guidance, for example the whoosh test, this was explained in terms of using the test to support clinical decision making but not as a test in isolation. There were multiple described reasons for behaviours that others may see as unsafe.

5.1.10 Doctors in training describe ‘learning from their seniors’ in relation to some clinical procedures, including NG tube placement and specifically position confirmation. It is arguable that these staff are witnessing actions that national guidance considers to be unsafe, and see this as accepted and/ or normal practice and follow what they have seen in practice. This may offer insight into why national patient safety guidance and alerts are not followed, that is, because staff follow observed behaviours. This reflects findings in other research where the barriers to change include social influences (Taylor et al, 2014; Bradford Institute for Health Research, 2012).

5.1.11 The CQC published a report exploring Never Events as a whole and why they happen, entitled ‘CQC, opening the door to change’ (Care Quality Commission, 2018a), on request of the Secretary of State for Health. The report focused particularly on culture and identified the following, with associated recommendations:

  • Never Events continue to happen
  • staff struggle to cope with the large volume of guidance meant to support them
  • there are issues with collaborative working
  • there needs to be more education and training in relation to safety
  • Never Events, culture and behaviours need to be a focus nationally
  • leaders need to embed safety culture
  • a better alerting system is needed for safety.

5.1.12 In response, the National Patient Safety Alerting Committee has agreed common standards and thresholds for national patient safety alerts to align all organisations that issue national alerts (NHS England, 2019).

5.1.13 The NHS Patient Safety Strategy (NHS England and NHS Improvement, 2019) includes a section on Never Events. It acknowledges that Never Events still occur and that prevention of the most common Never Events relies on repeated completion of procedural safety requirements such as checklists and training. Never Events prevented by a oneoff technical solution are much rarer. Technical innovations that act as barriers to people getting things wrong can have a greater impact on Never Event prevention.

5.1.14 To date, HSIB has undertaken several national investigations associated with Never Events. A national learning report will be published in early 2021 that systematically reviews the themes identified from 10 HSIB national investigations.

5.1.15 It therefore appears that the wider NHS system is working more collaboratively to understand the contributory factors in the recurrence of Never Events and the challenges faced in identifying design solutions.

5.2 Current available technology

5.2.1 pH strip readers that determine the colour of pH strips are available. However, there are conflicting reports about the accuracy / effectiveness of comparing pH paper to a calibrated hand-held pH meter (Fernandez et al, 2010). The accuracy and cost-benefit of pH strip readers were outside the scope of the investigation and were not considered further. It was reported by one trust that staff felt more reassured using a pH reader although the costs were significant. A pH reader was not used at the Trust where the reference event happened.

5.2.2 CORTRAK 2 EAS [9] is used as an adjunctive technology to aid in the placement of NG tubes (National Institute for Health and Care Excellence, 2016). It uses electromagnetic sensing technology to track and display the path of the feeding tube during a placement procedure and must be used with device-specific CORTRAK enteral feeding tubes. The accuracy and cost-benefit of CORTRAK 2 EAS was outside the scope of the investigation, however, it spoke to staff at one trust who had used the device in critical care when they could not rely on pH or failed to obtain an aspirate. CORTRAK was not used for confirmation of the initial NG tube placement but only for subsequent daily checks in this specific trust. Staff reported that the device reduced the requirement for X-ray confirmation. Staff still experienced issues with reliability. CORTRAK was not used at the Trust where the reference event happened.

5.3 Ongoing research to improve confirmation of NG tube placement

5.3.1 The investigation found there is ongoing national research to find a more reliable method to check NG tube placement.

5.3.2 There have been many studies and review articles which suggest a promising method of NG tube confirmation technology. However, there are both advantages and limitations to the methods considered. These have been described in the literature (Fan et al, 2017).

5.3.3 Medical Research Council funding had been awarded to develop a solution to tackle the safety issue of incorrect NG tube placement. The Medical Research Council funded work aims to develop, build, and test a new portable, sensor-based device known as NGSure® to give an accurate check of NG tube position. NG-Sure® works using sensor technology, measuring gases or chemicals at the end of the NG tube, known as volatile organic compounds, to create ‘smell fingerprints’, in addition to a pH reading. These fingerprints differ depending upon where the NG tube is situated (stomach, oesophagus, or lungs). The project commenced in January 2019 and was anticipated to take three years.

5.3.4 In addition to the research above, the investigation was advised of a system that is available for use via NHS supply chain called NGPOD®. The NGPOD® system consists of a single-use fibre optic sensor (NGPOD® sensor) and a small handheld light source and detector (NGPOD®). The fibre optic sensor is fully inserted down a placed NG tube. The sensor is then connected to the handheld NGPOD® and a test button is pressed. The NGPOD® returns a green tick or a red cross based on the pH level at the tip of the sensor. The sensor can then be removed from the NG tube and discarded. A multi-site study began in May 2019, following previous research trials, and it is expected that an evaluation report will be published in spring 2021. The study includes NG tube placement checks made after the first insertion of the NG tube, as well as repeat testing immediately before the administration of liquids.

5.3.5 Anderson et al (2016) noted that patients on acid-suppressing medication never had acidic gastric aspirates which made pH tests falsely negative. The researchers developed and validated a lipase (stomach enzyme) test that was compatible with non-acidic gastric aspirates to tackle the pH testing issue. The study showed that the sensitivity of the lipase test (sensitivity 97.2%) was significantly better than pH (sensitivity 65.7%). It concluded that the lipase test showed a true positive when stomach aspirates were not acidic and was significantly more accurate than pH testing (Anderson et al, 2016). The researchers’ intention is to develop the lipase test prototype and create a more viable daily NG tube position test for patients on acid suppression both in hospital and in the community.

5.3.6 The investigation spoke with the research team at Imperial College Hospital and found that lipase testing was going through clinical trials, including lipase testing with paediatric patients. The research team was also exploring different ways to present the lipase results to avoid ambiguity in readings.

5.3.7 In addition to the above, there are 15 Academic Health Science Networks (AHSNs) across England. These were established by NHS England in 2013 and relicensed from April 2018 to operate as the innovation arm of the NHS to spread innovative ideas and technologies at pace and scale. Their innovation exchange offers access to business expertise from AHSN teams across the country. The innovation exchange has not, as yet, been asked to consider NG tube safety as one of its priorities.

5.3.8 The investigation considered there was a need to co-ordinate work to understand the current evidence base and any further research needs for safety solutions to confirm NG tube placement. This would then enable the system to commission larger-scale research based upon the evidence identified to support the implementation, authorisation, and national adoption of safety solutions to confirm NG tube placement. It was apparent during discussions with NHS England and NHS Improvement and the Department of Health and Social Care, that there is a significant gap within the current NHS infrastructure in the assessment of the current evidence base and identifying research needs to support improvements in patient safety. NHS England and NHS Improvement and Department of Health and Social Care expressed an intent to identify critical research needs and therefore HSIB makes the following safety recommendation:

HSIB makes the following safety recommendation

Safety recommendation R/2020/107:

It is recommended that NHS England and NHS Improvement works with the Department of Health and Social Care and others, to identify the process by which the NHS can identify and commission necessary research to support improvements in patient safety. This would include research to confirm nasogastric tube placement.

5.4 Reporting, regulation and procurement

The Medicines and Healthcare products Regulation Agency Yellow Card scheme

5.4.1 The Medicines and Healthcare products Regulatory Agency (MHRA) is the ‘Competent Authority’ and also the ‘Designating Authority’ for medical devices for the UK. The MHRA administers and enforces the law on medicines and medical devices in the UK and is responsible for their safety.

5.4.2 The MHRA’s role is to protect and promote public health and patient safety by ensuring that medicines and medical devices meet appropriate standards of safety, quality, and efficacy.

5.4.3 The MHRA runs the Yellow Card scheme (Medicines and Healthcare products Regulatory Agency, 2020). This is the system used in England for collecting and monitoring information on suspected safety concerns involving medicines and medical devices. Reporting is voluntary by health professionals and/or patients.

5.4.4 Adverse incidents involving any medical device or in vitro diagnostic [10] medical device should be reported to MHRA via the Yellow Card scheme. A medical device may not carry a CE mark, for example if it is counterfeit, and this would still be reportable. pH testing strips for human gastric aspirate are an example of a medical device.

5.4.5 The investigation was made aware that the incident involving Fabian’s mis-placed NG tube had not been reported to the MHRA.

5.4.6 It is important for people to report problems they have experienced with medicines or medical devices as the information is used to identify issues which might not have been previously known about. The MHRA will review the product if necessary and take action to minimise risk and maximise benefit to patients.

5.4.7 It is understood that the MHRA has a data sharing agreement with NHS England and NHS Improvement, to share incident reports uploaded to the National Reporting and Learning System (NRLS) related to medicines or medical devices. The MHRA advised that it was not aware of individual details of reported incidents related to pH testing strips and Never Events involving misplaced NG tubes. The investigation was advised however that the MHRA was aware of the thematic issue of Never Events related to misplaced NG tubes.

5.4.8 A previous HSIB investigation, ‘Design and safe use of portable oxygen systems’ (Healthcare Safety Investigation Branch, 2018), found that the number of reports made through the Yellow Card scheme regarding issues with portable oxygen systems was significantly lower than the number of incidents being reported through NRLS on the same topic.

5.4.9 The purpose of the Yellow Card scheme is to provide an early warning that the safety of a product may require further investigation.

5.4.10 The MHRA was responsive to the investigation’s concerns regarding variability in pH testing strips despite not being aware of issues with pH strips for human gastric aspirate. It contacted three manufacturers listed on the NHS Supply Chain catalogue and asked:

‘Is it possible for a device user to use a competitor’s or a nonCE marked product colour reference chart to mis-read the aspirate pH result, and attain a valid result? Please provide any risk mitigators you have in place, or have put in place, to prevent such a scenario?’

(Medicines and Healthcare products Regulatory Agency, 2019).

5.4.11 Feedback was received which unanimously stated only to use the pH strips with the compatible container colour chart and that the key was education and posters to ensure correct use. The manufacturers recognised 77 that as the pH indicator colour strips vary, it would be incorrect to compare one manufacturer’s pH testing strip against another manufacturer’s colour reference chart. Mitigations to minimise risks included that users should ensure that the strips are used with the corresponding colour chart on the container. In addition, manufacturers provide educational posters and training.

5.4.12 After consulting with different manufacturers of testing strips, the MHRA concluded that:

‘…there is very little in terms of the product itself that can be changed. It would appear that the issue arises as a result of user issues, therefore further training to promote that only compatible charts and strips be used, could be worthwhile, as could suggesting that only one pH strip manufacturer is used in a trust.’

(Medicines and Healthcare products Regulatory Agency, 2019).

5.4.13 Given the above comment regarding there being very little in terms of the product itself that can be changed, there will remain a risk to patient safety as the variability will continue and the associated risks are placed onto the user.

5.4.14 NHS England and NHS Improvement informed the investigation that there are data sharing agreements in place with national bodies such as the MHRA to enable sharing of information from NRLS. This covers all incident data relating to medical devices and additional bespoke reports can be created on request. However, there does not appear to be a shared system-wide knowledge of the reported incidents related to confirmation of NG tube placement, for example, pH testing strips, because of limitations in interoperability of national reporting systems being used by the NHS.

5.4.15 The investigation was told that applications for data sharing from other bodies with safety responsibilities are welcomed by NHS England and NHS Improvement, but the effectiveness of data sharing is reliant on other bodies having the resources to review the incidents they receive. The risks of not having a reliable process to alert and communicate safety concerns between national bodies was recently expressed in the report of the Independent Medicines and Medical Devices Safety Review (Cumberlege, 2020).

HSIB makes the following safety observation

Safety observation O/2020/087:

It may be beneficial if national organisations including the Medicines and Healthcare products Regulatory Agency, NHS Supply Chain and NHS England and NHS Improvement review arrangements for ensuring all medical device related incidents, Yellow Card reports, or other device safety related information, including any involving concerns with pH or X-ray in the context of nasogastric tubes, are shared between the relevant organisations to inform their respective patient safety responsibilities.

HSIB makes the following safety recommendation

Safety recommendation R/2020/108:

It is recommended that NHS Supply Chain and the British Standards Institution work together (engaging other system leaders as appropriate, such as the Medicines and Healthcare products Regulatory Agency and NHS England and NHS Improvement), to develop and publish an agreed standard to minimise the risks relating to human errors in the use of pH strips designed for testing human gastric aspirate at the bedside. The standard should consider product design, regulatory standards, procurement practices and human factors engineering to provide a consistent approach that can be embedded within NHS Supply Chain product specifications

CE marking approval

5.4.16 A CE mark is a baseline standard for placement on the EU market. pH strips do not need a Notified Body [11] to approve them to get a CE mark. The manufacturer can self-certify and give the product a CE mark once they are satisfied with their own data. This is allowable under the current EU Invitro Diagnostic Directive (IVD). Under the new Invitro Diagnostic Regulation (IVDR) taking force in the EU in May 2022, there will be a reclassification of devices according to risk under the new IVDR regulation (EU) 2017/746 (British Standards Institution, 2020a). pH strips for human gastric aspirate will become a class B device (British Standards Institution, 2020b). This will mean manufacturers will need a Notified Body approval to obtain a CE mark. However, as the UK has left the EU, the UK (MHRA and Office for Life Sciences (OLS)) has decided not to adopt the new IVDR and will continue to operate an IVD type approval. This means that pH strips will not have the same scrutiny in the UK as they will have in the EU as they will continue to be self-declared by the manufacturers.

5.4.17 Currently, if there is a serious patient safety incident involving medical devices to confirm NG tube placement, for example pH testing strips, the incident should be reported via the Yellow Card scheme. The information would be shared with and registered on the European database Eudamed. However, after the UK has completed the transition in January 2021 from the EU, the MHRA will no longer have access to Eudamed data. This means that, in the post-transition regulatory environment, the MHRA will only know about such cases occurring within the UK.

HSIB makes the following safety observation

Safety observation O/2020/088:

It would be beneficial for the Department of Health and Social Care to consider post-Brexit arrangements for sharing patient safety incident data with Europe

Procurement

5.4.18 pH testing strips for human gastric aspirate are currently procured for trusts by NHS Supply Chain (NHSSC) and made available via the NHSSC catalogue. However, not all trusts purchase via NHSCC and NHS trusts can purchase directly from manufacturers. Independent hospitals providing NHS-funded care do not have access to NHSSC. There are multiple manufacturers and variability in design of strips.

5.4.19 The concerns regarding the variability in pH testing strips was shared with NHSSC. The investigation was made aware of plans to bring the systemwide intelligence together to inform future procurement plans and specification development along with system-level response to issues. It was anticipated that there would be reduced variance in patient outcomes due to standardisation of product features and reduced staff training requirements as product categories would meet defined user requirements.

5.4.20 The investigation was told that NG tube confirmation using standardised pH paper could be an area of focus to develop using essential specifications.

5.4.21 The investigation was informed that this specification approach would drive improving standards and support innovation within the clinical manufacturing industry. NHSSC told the investigation that it would review the efficacy of devices used in practice, supported by intelligence from clinical partners and other agencies. This would support mitigation of risk to patients and users, for example by suspension or removal of a product from the list of products it will supply with appropriate alternatives put into place.

HSIB makes the following safety recommendation

Safety recommendation R/2020/109:

It is recommended that NHS Supply Chain develops essential specifications to support the clinically-led procurement of devices to include devices to confirm nasogastric tube placement, for example, pH testing strips. The essential specifications should set out a range of factors critical to inform the selection by NHS Supply Chain of a product including, but not limited to: clinical output requirements; design and ergonomics; human factors and intended use; and limitations on use and usability. Critically, these specifications should ideally be established in partnership across the healthcare system with clinicians, healthcare professionals and safety leads, while maximising best practice.

5.5 New ways of working

Use of electronic systems

5.5.1 The investigation spoke with two trusts that were in the early stages of implementing electronic pathways to aid NG tube policy use. The electronic system offered a series of prompts and checklist items which clinicians could complete while the NG tube was being inserted, or once the NG tube was inserted. The NG tube electronic system would then serve as a checklist to ensure certain tasks in the process had been completed.

5.5.2 It was anticipated that the system would offer several benefits:

  • There is an audit trail of the NG tube insertion.
  • If aspirate is unable to be obtained or the pH is outside the ‘safe range’ a flowchart of actions to take is presented to the clinician.
  • The system will alert clinicians if the tube has moved more than 2cm from the original sited tube length.
  • X-rays can be viewed electronically and so can be accessed throughout the hospital. This means clinicians can approve X-rays remotely without having to be with the patient, enabling NG feeding to commence as soon as possible. The Royal College of Radiologists highlights that there is the risk of sub-optimal conditions for clinical evaluation due to environmental conditions and the device X-rays may be viewed on (The Royal College of Radiologists, 2019a).
  • The system mandates commenting on the four criteria for interpreting the position of the NG tube on X-ray.
  • There are prompts to alert if the NG tube has expired or is expiring soon.
  • It provides an opportunity to capture and analyse NG tube data to provide greater oversight and intelligence around NG tube insertion and confirmation of placement.

5.5.3 Of the two trusts that were adopting the electronic system, one was about to roll out the system and the other had piloted the system for six months. They had launched the system in several wards. Neither of the trusts had data on the impact and use of the system. They reported that evaluation was key and were looking to evaluate the system in future.

Using trained experts

The Nasogastric Special Interest Group (NG-SIG) of the British Association of Parenteral and Enteral Nutrition (BAPEN) published a position paper on NG safety (Jones, 2020). The position paper highlighted 18 findings and included recommendations. It concluded that the ‘perception of nasogastric feeding tube insertion as a “simple” procedure must be changed to that of a “complex” and dangerous procedure and limited to properly trained and competent healthcare professionals’. The position paper stated:

‘The NG-SIG of BAPEN would… strongly support restriction of NGT [NG tube] insertion to registered nurses, dietitians, radiographers and medical staff (including radiologists and intensivists) who have undergone appropriate training and ongoing competency assessment. The present practice of training all nurses to place NGTs should be replaced by a 2-tier system. The insertion and reinsertion of NGTs should be restricted to selected staff (expert operators) as above but for practical reasons, the subsequent checking of tube tip position before each use by pH assessment and external length should still be the remit of all competent professional staff as above.’

(Jones, 2020)

5.5.4 Discussion with the research team at Imperial College Hospital also suggested that limiting the responsibility of insertion and confirmation of NG tube placement to a limited cohort of ‘experts’ may be beneficial. The research team commented that current methods had huge potential for error, particularly for pH testing. In a simulated study, Borsci et al (2017) found a 11.15% error rate in participants’ readings of pH strips, with important implications for decision making regarding NG tube placement. (Borsci et al, 2017). The team suggested that there may not currently be experts in pH reading and NG confirmation of placement and that it would be unrealistic to retrain the whole health service in what is an unsafe and error-prone procedure. Like BAPEN, they also suggested regularly assessing the competency of experts.

5.5.5 The Imperial College Hospital team stated that using specifically trained experts would need to be trialled and any training would need to be defined, developed, and tested using a human factors approach prior to any widespread implementation.

The role of the radiographer to improve patient safety related to NG feeding in adults

5.5.6 According to national guidance (NHS Improvement, 2016b), interpretation of X-rays would typically be done by medical staff or by radiologists. Radiologists are doctors who are specially trained to interpret diagnostics images such as X-rays, MRI and CT scans. Radiologists also perform interventional procedures, such as angiograms or biopsies (Royal College of Radiologists, n.d.).

5.5.7 A radiographer is a registered healthcare professional and they undertake a broad portfolio of either diagnostic examinations or radiotherapy procedures (The Society and College of Radiographers, n.d.).

5.5.8 The Quality standard for Imaging (Royal College of Radiologists, 2019b) has a requirement to ensure communication of X-ray reports within specified timescales and that there are systems in place to manage unexpected findings and potential medical emergencies.

5.5.9 NG tube removal by radiographers has been trialled in a single site NHS trust with positive results (Law and Kelly, 2011). This research was used as a basis for a large multi-site teaching trust pilot.

5.5.10 The investigation visited this large multi-site teaching hospital which had expanded the role of the radiographer to contribute to risk reduction regarding feeding through misplaced NG tubes. The trust published its results (Roe et al, 2017). Two main roles were developed for radiographers: first, consistently commenting on the tube position on the image; and second, taking a defined role in NG tube management by removing misplaced tubes (Roe et al, 2019).

5.5.11 The initial trial implemented a system to determine the accuracy of radiographer comments against the standard of radiologist reports to see whether the role of the radiographer helped reduce the number of Never Events. In addition, as part of its research the trust considered radiographer confidence in undertaking their new role and their evaluation of patient benefit from this system of working. It concluded that after focused training, the role of a radiographer in NG tube confirmation by X-ray was a safe, effective, sustainable and workable solution to image misinterpretation issues relating to NG tube Never Events. It was suggested the system should be considered for wider implementation in healthcare (Roe et al, 2017).

5.5.12 The radiographer will check any X-ray for NG tube position, even if the request is not specifically for NG tube confirmation of placement. They check that the NG tube is in position and are empowered to act if not. The trust had examples of how radiographers flagged a tube that may have become displaced on a chest X-ray that had been carried out for other reasons before any harm occurred to the patient.

5.5.13 The studies using radiographers suggest they are guided by rigidly following a protocol and this leads them to confirming if the tube is in the correct place (or is not and should be removed). This is considered to add an additional safety net or a potential barrier to X-ray misinterpretation by a clinician because another trained expert is questioning the position before the doctor.

While not directly relevant to the reference event, the following observation and recommendation has been made given the continued risk of NG tube Never Events following incorrect X-ray interpretation:

HSIB makes the following safety recommendation

Safety recommendation R/2020/110:

It is recommended that the British Society of Gastrointestinal and Abdominal Radiologists, working with Health Education England and the Society and College of Radiographers, develops and publishes a national standardised competency-based training programme for X-ray interpretation to confirm nasogastric tube placement. The competency-based training programme will include the referral process for X-ray to confirm nasogastric tube position and the subsequent reviewing, recording and communication of the clinical evaluation of the X-ray findings prior to initiation of feed. The standards must meet the Ionising Radiation (Medical Exposure) Regulations IR(ME)R requirements. The competency-based training programme will lead to a recognised accreditation for those qualified to clinically evaluate and record their findings, for example doctors, radiographers and advanced care practitioners. The accreditation certificate will be transferable across NHS care providers in England.

HSIB makes the following safety observations

Safety observation O/2020/089:

It would be beneficial if the (recommended) national standardised competency-based training programme for nasogastric X-ray interpretation to confirm nasogastric tube placement will be made a contractual and/or regulatory requirement for all healthcare providers to implement and evidence ongoing compliance with.

Safety observation O/2020/090:

It may be beneficial if accreditation for reviewing, recording and communication of the clinical evaluation of the X-ray findings, prior to initiation of feed, is limited to specific staff groups trained in confirming nasogastric tube placement, for example reporting radiographers or radiologists.

6 COVID-19

6.1 Introduction to COVID-19

6.1.1 Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus (World Health Organization, 2020a). The World Health Organization (WHO) recently concluded that, based on the current evidence, transmission of COVID-19 is primarily through respiratory droplets and contact (World Health Organization, 2020b).

6.1.2 Guidance has been updated to reflect pandemic evolution and the changing level of risk of exposure to COVID-19 in healthcare settings in the UK. There was believed to be an increased risk for healthcare staff subjected to repeated risk of contact and droplet transmission during their daily work.

6.1.3 The COVID-19 pandemic has posed several challenges for the national healthcare system. This has required the reconfiguration of environments, repurposing of equipment, acquisition of new equipment and cross-skilling of staff.

6.1.4 COVID-19 is a complex disease which, in the early stages, primarily affects the respiratory system. This leads to a pneumonia-like illness. It has been suggested that confirming nasogastric (NG) tube position during COVID-19 has been more challenging than usual (British Association of Parenteral and Enteral Nutrition, National Nutritional Nurses Group, Intensive Care Medicine, Intensive Care Society, Royal College of Anaesthetists, 2020).

6.2 Safety alert/updates during COVID-19

6.2.1 National healthcare organisations have issued several COVID-19 related patient safety alerts. NHS England and NHS Improvement produced updates on issues related to COVID-19 and the impact on patient safety. The updates were pulled together to disseminate key information that trusts’ patient safety heads might need to know but could otherwise miss. They were not intended for general circulation within organisations.

6.2.2 Special considerations were agreed for confirming NG tube placement for COVID-19 patients. In summary, professional bodies for nutrition, anaesthetics and intensive care produced an aidememoire, entitled ‘Nasogastric tube (NGT) placement checks before first use’, to help prevent NG tube Never Events in critical care settings during the COVID-19 response (British Association of Parenteral and Enteral Nutrition, National Nutritional Nurses Group, Intensive Care Medicine, Intensive Care Society, Royal College of Anaesthetists, 2020).

6.2.3 The aide-memoire was not designed to replace existing, established NHS Improvement compliant practice of NG tube confirmation for areas where there had been no significant change to staffing. However, it was considered that staff returning to practice, or redeployed to critical care environments, including in Nightingale hospitals, would be helped by reminders of established safety steps in a form that can be used for all critical care patients, rather than requiring different processes for different patients.

6.2.4 The advice in the aide-memoire was to:

‘Use only x-ray confirmation before FIRST use DO NOT use pH testing to confirm placement before first use, in view of the increased risks of prior unrecognised oesophageal regurgitation or respiratory aspiration. Once initial tube position has been confirmed radiologically, then external tube markers and pH testing can be used in subsequent tube position checks.’

(British Association of Parenteral and Enteral Nutrition, National Nutritional Nurses Group, Intensive Care Medicine, Intensive Care Society, Royal College of Anaesthetists, 2020)

6.2.5 The investigation heard from people and organisations who said while the guidance was issued with good intent, it did not follow the normal channels for dissemination and caused confusion for organisations.

6.2.6 Staff told the investigation that the aide-memoire caused some confusion within trusts as those with a stable and established workforce used to using pH testing as first-line confirmation could continue to do so, whereas those in unfamiliar environments should be using X-ray. The investigation heard from trusts that stated they continued to use their existing local policy rather than suddenly adopting a new process.

6.3 COVID-19 and the impact on NG tube insertion and confirmation

6.3.1 The coronavirus outbreak was a rapidly evolving situation and the investigation has considered this in relation to NG tube insertion and safe confirmation of NG tube position in adults in acute hospitals.

6.3.2 It was considered that there were increased risks associated with patients who had been put into a prone position (lying on their front) for clinical reasons, as there is an increased risk of regurgitation of gastric contents into the oesophagus and aspiration into the lungs which will render pH checks less reliable.

6.3.3 The NG tube safety position paper reported on the COVID-19 crisis and the concerns in relation to NG tube position confirmation during the pandemic (British Association of Parenteral and Enteral Nutrition, 2020).

6.3.4 Staff told the investigation that in some of their trusts, there was a reported increase in requests for X-rays. However, there were concerns that X-rays remain a risk when used to confirm NG tube placement.

6.3.5 X-ray images associated with patients with a COVID-19 infection were also more difficult to interpret because of the ‘ground glass’ appearance – meaning that a hazy lung opacity shows up on imaging.

6.3.6 Staff told the investigation that they were working in unfamiliar environments and therefore not used to working with patients with NG tubes. There were reported concerns that the education and competency assessments were rushed.

6.4 Summary of reported incidents during the COVID-19 pandemic

6.4.1 There were eight Never Events reported on the Strategic Executive Information System (StEIS) from March to July 2020. A qualitative analysis of these events was performed.

6.4.2 In two of the Never Event reports, the nursing team was not able to get any aspirates for pH checks. In addition, the tube position was not being confirmed after movement or when there was clinical concern. For example, if there is resistance or aspirate cannot be obtained. These scenarios are common and link back to the investigation findings that these do not prompt the staff member to seek further confirmation.

6.4.3 It remains unclear from a review of the reports whether pH is always used as the first-line check for NG tube placement.

6.4.4 Of the eight Never Event reports, misinterpretation of the X-ray was a factor in three reports. The reports provided additional evidence that the fourstage X-ray confirmation (NHS Improvement, 2016b) was not being used and the inference from the summary details is that ‘tip below diaphragm=fine’. Guidance already reminds the healthcare professional that if the X-ray is not clear enough to view the ‘four criteria’, to seek radiology advice. Simply looking for ‘tip below diaphragm’ is not enough as misinterpretation using this technique is the cause of most fatalities from feeding through misplaced tubes.

6.4.5 There are examples of where a radiographer informed a member of staff that an NG tube was in the wrong place, but the tube was not removed promptly and feeding was commenced.

6.4.6 It is possible that imaging will only be requested if considered clinically urgent because donning and doffing of personal protective equipment (PPE) by radiographers as they move between clinical areas, was reported as problematic. In one reported instance the X-ray confirmation of NG tube positioning was considered non-urgent, so the imaging did not take place in a timely way.

6.4.7 In one of the local StEIS investigations it was reported that low oxygen saturations could have been assumed to be associated with COVID-19 rather than inadvertent administration of NG feed into the lungs or the pleural cavity. This is consistent with concerns raised by the British Association of Parenteral and Enteral Nutrition (BAPEN).

6.4.8 It was reported by one trust via StEIS that the capacity to initiate investigations into misplaced NG tubes was limited and it was considered more important to protect the psychological welfare of staff. Access to clinical notes in COVID-19 areas was restricted preventing timely investigation and reflected pressures on the system at that time.

6.5 NG tube insertion as an aerosol generating procedure

6.5.1 Certain work environments and procedures convey a higher risk of COVID-19 transmission. Procedures in medical and patient care that result in the production of airborne particles (aerosols), known as aerosol generating procedures (AGPs), present a risk of aerosolised transmission. The highest risk of transmission of respiratory viruses occurs during AGPs of the respiratory tract. The use of enhanced respiratory protective equipment is indicated for healthcare professionals performing or assisting in such procedures.

6.5.2 Guidance was produced with the intention of setting out clear and actionable recommendations on the use of PPE, as part of safe systems of working, for health and social care workers relative to their day-to-day work.

6.5.3 The investigation was made aware of letters written by the President of BAPEN to the Secretary of State and Public Health England requesting the redefinition of NG tube insertion as an AGP. At time of writing, this situation remains unresolved.

6.5.4 Social media coverage suggested there was significant debate about whether NG tube insertion should be classed as an AGP. There appeared to be inconsistency in trusts’ approaches, with some continuing with ‘it’s not an AGP’ and others considering it an AGP that required the donning of full PPE. Staff told the investigation that a pragmatic approach was taken, for example, “if you are worried your patient is going to cough excessively then it is entirely reasonable to wear full gown, visor etc”. It was also reported that over time, staff became more comfortable with basic PPE only.

6.6 Impact on research

6.6.1 The investigation was made aware that the pandemic had had a direct impact on research discussed in section 5 of this report. One multisite research study was considered ‘non-essential’ and therefore paused. It was reported that there was a risk of NG aspirates being transported from the hospital to a laboratory, and there would be a risk to the person analysing it if a sample were from a patient with COVID-19. Another piece of research referred to in section 5 did continue.

7 Summary of findings, safety recommendations, safety observations and safety actions

A critical step to ensure correct placement of an NG tube is reliable confirmation of tube position prior to commencing feeds.

The HSIB investigation reviewed NG tube insertion and placement verification in the context of local and national practice and guidelines. The national investigation applied a human factors approach to understanding the processes, practices, interactions among people, and other elements of system performance involved with the insertion of NG tubes and confirmation of their position. The investigation considered existing guidance as well as the procurement and implementation of the equipment required for NG tube insertion and confirmation, and how staff acquire the competencies to do this safely. The factors that contributed to the reference event have been grouped under two key processes which were the focus of analysis in this investigation:

1 Confirmation of NG tube placement using pH testing.

2 Interpretation of chest x-rays for clinical deterioration and identification of NG tube position.

Summary of Findings

Given the serious and ongoing safety risks, HSIB’s initial national findings were published in an interim bulletin on 5 February 2020 and early safety observations were made. The findings listed below encompass the overall findings of the national investigation, including those from the interim bulletin. The investigation found:

General findings

1 The placement of NG tubes into the lungs rather than the stomach and fluid, medicine or feed being passed through them is defined as a Never Event in the NHS. However, there are no systemic barriers to preventing feeding into an NG tube that has been accidentally placed in the lung.

2 There is ongoing research to find a reliable design solution to reduce the risk of misplaced NG tubes. However, these projects will not be completed for a few years. As such, a new technological solution is not imminent.

3 Local trust policies generally reflect national guidance. However, there are limitations in their use because of their length. Staff told the investigation they know the guidance is there, but such guidance is too long to read.

4 There is significant variation in how existing safety standards are implemented and continually monitored.

5 Reporting NG medical device related incidents to the Medicines and Healthcare products Regulatory Agency (MHRA) via its Yellow Card scheme is less frequently done in comparison to NG tube related incidents reported on the National Reporting and Learning System or Strategic Executive Information System (national systems for reporting patient safety incidents).

6 New ways of working, and specifically extending the role of the radiographer to improve patient safety in NG tube position confirmation, have been effectively implemented and successfully evaluated in some organisations.

7 The introduction of measures to manage COVID-19 resulted in increased challenges for NG tube insertion and confirmation of tube placement. Findings related to pH testing

8 The process of confirmation of correct NG tube placement using pH testing strips is potentially unreliable and its complexity underestimated. The pH test cannot be used if stomach contents cannot be aspirated and will be inconclusive in patients with altered stomach pH. The investigation also identified concerns around the reliability and usability of pH strips.

9 There is a risk that organisations that insert NG tubes may have multiple types of pH strip in circulation, both CE marked, and non-CE marked.

10 Testing strips are ‘read’ by checking the colour on the strip against a colour chart on the container the strips are kept in. CE marked enteral pH testing strips from different manufacturers have different pH colour coding scales which are inconsistent. If a healthcare provider has more than one type of enteral pH testing strip in circulation at the same time, there is a risk of error when comparing the strips from one product against a container with a different pH scale. Therefore, having two or more types of CE marked strips in circulation could result in inaccurate readings.

11 The multiple types of strip present in the Trust where the reference event took place highlights the need for trusts to have reliable processes in place to implement changes that are required by national guidance – in this case, the removal of non-CE marked pH testing strips for testing human gastric aspirate.

12 There is no standard process on how to read a pH strip. A standard process needs to be defined.

13 Training on NG tube placement is available albeit variable in terms of delivery and content. The cascade model of training (where one group of staff is trained, then each trained staff member trains another group, and so on) has led to some staff ‘teaching’ the incorrect method for testing pH.

14 There is no consistent process for assessing and recording competency in NG tube placement and confirmation using pH testing.

15 There are clinical guidelines on the ‘safe range’ for pH and some trusts use a lower pH due to a perception that a lower pH is safer. Although a range of research has been carried out, there is no consistent research conclusion to guide what the best cut-off pH is to exclude placement in the respiratory tract. There is concern about use of ‘safe range’, and there have been no accredited clinical guidelines or research that would change the ‘safe range’.

16 The environment within which pH testing strips are being interpreted can increase the risk of error. In the reference event, this was particularly noted with the poorly lit environment. Findings related to X-ray

17 X-ray confirmation of NG tube placement is thought to be the most accurate method if a standard process is consistently followed (Metheny et al, 2019). However, incorrect X-ray confirmation and interpretation is the most common cause of NG tube incidents.

18 There is no consistent process for assessing and recording competency in NG tube placement and confirmation using X-ray. People described different ways of interpreting an X-ray. Even when staff are trained, they may still not follow the algorithm for interpretation and may still not identify NG tube misplacement.

19 All NG tubes are radio-opaque (which means they can be detected on an X-ray). However, it is important that when an X-ray is requested a specific requirement is given. The policy at the reference event Trust and other organisational policies refer to chest X-ray as opposed to NG X-ray. A specific NG X-ray will ensure more visibility below the diaphragm than a standard chest X-ray and therefore the language and choice of image request matters.

20 Whatever the reason for carrying it out, a chest X-ray will enable a clinician to spot incidental findings and is an opportunity to check NG tube position. However, in Fabian’s case, the rationale for chest X-ray was clinical deterioration and the NG tube position was not observed and was not being considered as a causal factor for his clinical deterioration. Therefore, there were missed opportunities in the reference event to identify the misplaced NG tube associated with inattentional blindness (people’s tendency to miss things that are visible because their attention is elsewhere) when interpreting X-rays.

21 There was not a formal radiology interpretation (report) of the X-ray. The responsibility for undertaking a clinical evaluation was delegated to the specialist critical care staff and underpinned by local policy (under the Ionising Radiation (Medical Exposure) Regulations (IR(ME)R) 2017 employer’s procedures). This is not uncommon and is an accepted practice (Care Quality Commission, 2018b).

22 Limited availability and detectability of vital information about NG tube displacement and re-insertion may adversely influence clinical assessment and decision making. This is further confounded by difficulties in the detectability of NG tubes on X-ray, and inattentional blindness when interpreting X-rays.

23 The context within which staff are interpreting X-rays influences their ability to accurately identify abnormalities. This includes factors such as the viewing environment, technical aspects such as display screen resolution, time pressures associated with the software, and the quality of X-ray images.

24 While workload was not a definitive causal factor in the reference event, it is recognised that workload, distractions, and concurrent task requirements will influence staff’s levels of attention. This may mean that protocols for X-ray interpretation are not followed.

25 While it is acknowledged that competency-based training is not a strong systemic barrier to improve safety, there was no standardised competency framework and delivery model for training and assessment in NG tube placement and undertaking placement checks. The potential to use specifically trained experts, such as radiographers, was considered but would need to be trialled. Any training would need to be defined, developed, and tested using a human factors approach prior to any widespread implementation.

HSIB makes the following safety recommendations

Safety recommendation R/2020/106:

It is recommended that Health Education England coordinates the development and publication of a national standardised competency-based training programme for nasogastric tube placement and confirmation by pH testing. The model may include simulation, observed practical assessment and ongoing competency assessment. The competency-based training programme would need to be defined, developed, and tested using a human factors approach prior to any widespread implementation. The competency-based training programme will lead to a recognised accreditation which will be transferable across the NHS care providers in England.

Safety recommendation R/2020/107:

It is recommended that NHS England and NHS Improvement works with the Department of Health and Social Care and others, to identify the process by which the NHS can identify and commission necessary research to support improvements in patient safety. This would include research to confirm nasogastric tube placement.

Safety recommendation R/2020/108:

It is recommended that NHS Supply Chain and the British Standards Institution work together (engaging other system leaders as appropriate, such as the Medicines and Healthcare products Regulatory Agency and NHS England and NHS Improvement), to develop and publish an agreed standard to minimise the risks relating to human errors in the use of pH strips designed for testing human gastric aspirate at the bedside. The standard should consider product design, regulatory standards, procurement practices and human factors engineering to provide a consistent approach that can be embedded within NHS Supply Chain product specifications.

Safety recommendation R/2020/109:

It is recommended that NHS Supply Chain develops essential specifications to support the clinically-led procurement of devices to include devices to confirm nasogastric tube placement, for example, pH testing strips. The essential specifications should set out a range of factors critical to inform the selection by NHS Supply Chain of a product including, but not limited to: clinical output requirements; design and ergonomics; human factors and intended use; and limitations on use and usability. Critically, these specifications should ideally be established in partnership across the healthcare system with clinicians, healthcare professionals and safety leads, while maximising best practice.

While not directly relevant to the reference event, the following safety recommendation has been made given the continued risk of NG tube Never Events following incorrect X-ray interpretation

Safety recommendation R/2020/110:

It is recommended that the British Society of Gastrointestinal and Abdominal Radiologists, working with Health Education England and the Society and College of Radiographers, develops and publishes a national standardised competency-based training programme for X-ray interpretation to confirm nasogastric tube placement. The competencybased training programme will include the referral process for X-ray to confirm nasogastric tube position and the subsequent reviewing, recording and communication of the clinical evaluation of the X-ray findings prior to initiation of feed. The standards must meet the Ionising Radiation (Medical Exposure) Regulations IR(ME)R requirements. The competency-based training programme will lead to a recognised accreditation for those qualified to clinically evaluate and record their findings, for example doctors, radiographers and advanced care practitioners. The accreditation certificate will be transferable across NHS care providers in England.

HSIB makes the following safety observations

Safety observation O/2020/086:

It would be beneficial if chest X-rays for acutely ill patients were reported by a radiologist, or a radiographer who has undertaken training, to enable them to report on examinations at an appropriate time. The report should include the position of an nasogastric tube if one is present on a chest X-ray.

Safety observation O/2020/087:

It may be beneficial if national organisations including the Medicines and Healthcare products Regulatory Agency, NHS Supply Chain and NHS England and NHS Improvement review arrangements for ensuring all medical device related incidents, Yellow Card reports, or other device safety related information, including any involving concerns with pH or X-ray in the context of nasogastric tubes, are shared between the relevant organisations to inform their respective patient safety responsibilities.

Safety observation O/2020/088:

It would be beneficial for the Department of Health and Social Care to consider post-Brexit arrangements for sharing patient safety incident data with Europe.

Safety observation O/2020/089:

It would be beneficial if the (recommended) national standardised competency-based training programme for nasogastric X-ray interpretation to confirm nasogastric tube placement will be made a contractual and/or regulatory requirement for all healthcare providers to implement and evidence ongoing compliance with.

Safety observation O/2020/090:

It may be beneficial if accreditation for reviewing, recording and communication of the clinical evaluation of the X-ray findings, prior to initiation of feed, is limited to specific staff groups trained in confirming nasogastric tube placement, for example reporting radiographers or radiologists.

Safety observation O/2020/056 (previously shared in interim bulletin):

It is important that organisations are aware that there is not a standard scale/colour scheme across the different manufacturers of CE marked enteral testing strips and they vary in scale (pH of 1-12, 0-6, 2-9 or 3-7). If organisations have CE marked enteral pH testing strips from more than one manufacturer in use at the same time, there is still a potential for error if a pH testing strip is compared against the incorrect box.

Safety observation O/2020/057 (previously shared in interim bulletin):

It is important when transitioning between any types of bedside testing equipment (not just pH strips) the potential for confusion between old and new stock is considered, and the transition managed to reduce that risk and to ensure that staff understand any difference between techniques needed with past and future brands of bedside tests.

HSIB notes the following safety actions

Safety action A/2020/034:

The Trust where the reference event happened, amended the timing of its daily aspirate check from midnight to 10:00 hours.

Safety action A/2020/035:

The Trust where the reference event happened checked the hospital clinical areas to confirm there were no other areas holding non-CE marked pH testing strips for human gastric aspirate.

Safety action A/2020/036:

The Trust where the reference event happened implemented and recorded training and competency assessments for all nursing staff prior to allowing them to insert and confirm placement of nasogastric tubes.

8 Appendix A

8 Appendix B Summary of legislative and regulatory guidance in relation to X-ray

The Ionising Radiation (Medical Exposure) Regulations (IR(ME)R) 2017 (Department of Health and Social Care, 2017) is legislation which provides a framework intended to protect patients from the hazards associated with ionising radiation (the type of radiation produced by X-rays and other imaging procedures). The regulations in Great Britain are enforced under section 15 of the Health and Safety at Work Act 1974 (Health and Safety Executive, 1974). A guide to understanding the implications of IR(ME)R in diagnostic and interventional radiology and diagnostic nuclear medicine (British Institute of Radiology, Society and College of Radiographers and The Royal College of Radiologists, Institiute of Physics and Engineering in Medicine, Public Health England, 2020) explains the principles behind the regulations using a practical approach. In addition, non-statutory guidance has been produced by the Department of Health and Social Care which includes good practice notes to support and clarify IR(ME) R (Department of Health and Social Care, 2018). Under IR(ME)R, the employer is legally responsible for ensuring the regulations are complied with.

The definition of the referrer, practitioner and operator are stated within Regulation 2 of IR(ME)R and will be determined by the employer and will include their scope of practice (that is, the range of tasks that may be undertaken by them). Those who are entitled under these Regulations as referrer, practitioner or operator could be identified in a variety of ways in the employer’s procedures, for example by profession, grade, or individual name. In practice, decisions about who is entitled to act as a referrer, practitioner or operator, and the scope of practice, should be taken at local level and may involve agreement between the employer and the healthcare professionals involved in exposures. Entitlement and scope of practice should be supported by education and training. ‘Implications for clinical practice in diagnostic imaging, interventional radiology and nuclear medicine’ (British Institute of Radiology, The Royal College of Radiologists, Society and College of Radiographers, Institute of Physics and Engineering in Medicine and Public Health England, 2020 (British Institute of Radiology, Society and College of Radiographers and The Royal College of Radiologists, Institiute of Physics and Engineering in Medicine, Public Health England, 2020) explains the requirements for each role and appendix 6 of this guide provides information on group entitlement.

IR(ME)R also requires ‘adequate training’ for practitioners and operators. Adequate training is that which satisfies the requirements of Schedule 3 of the regulations and sets out details of the training which a practitioner or operator must have successfully completed, as relevant to their functions or area of practice, in order to be permitted to carry out medical exposures or practical aspects under the Regulations. Regulation 17 prohibits any practitioner or operator from carrying out an exposure or any practical aspect without having been adequately trained (Department of Health and Social Care, 2017; Department of Health and Social Care, 2018). Schedule 2 (Department of Health and Social Care, 2017) sets out a list of matters that must be covered in the employer’s procedures. Regulations do not require the referrer to be adequately trained. Nevertheless, there is a requirement for referrers to understand their duties as specified under Regulation 10 and to comply with the employer’s procedures as in Regulation 6(2) (Department of Health and Social Care, 2017).

Guidance has been written by the Society of Radiographers and other professional bodies to help those non-medical healthcare practitioners (including radiographers) registered with a healthcare regulatory body who wish to take on the role of IR(ME)R ‘Referrer’ within a clinical imaging department (Royal College of Nursing, General Chiropractic Council, General Osteopathic Council, Chartered Society of Physiotherapy, NHS Alliance, The Royal College of Radiologists and Society and College of Radiographers, 2008). Following this publication, the College of Radiographers developed an IR(ME)R awareness training study day for nurses and allied health professionals, although the investigation has not reviewed the delivery, content or assessment criteria of this training. Similar training is generally available within local clinical imaging departments.

Although not a requirement of the Regulations, it is often the case that that the employer will identify a senior member of staff who holds responsibility for IR(ME)R documentation for the organisation and these responsibilities may also involve the assessment of staff competence where appropriate and maintenance of training records (British Institute of Radiology, Society and College of Radiographers and The Royal College of Radiologists, Institiute of Physics and Engineering in Medicine, Public Health England, 2020).

In addition to local organisation training, Health Education England e-Learning for Healthcare, in partnership with the Institute of Physics and Engineering in Medicine, has delivered a free training resource called e-IRMER (Health Education England, 2020). e-IRMER is an interactive online training resource supporting the training of NHS and other healthcare professionals who work with patients undergoing ionising radiation medical exposures. It is described as providing easy access to learning materials, and, through formative and summative assessments, allows the learner to both develop competence and demonstrate compliance with the regulatory requirements of the IR(ME)R.

9 References

Anderson, O., Carr, R., Harbinson, M. and Hanna, G. B. (2016) Development and validation of a lipase nasogastric tube position test. British Medical Journal Open Gastroenterology, 3 (1), e000064.

British Association for Parenteral and Enteral Nutrition, National Nutritional Nurses Group, Intensive Care Medicine, Intensive Care Society, Royal College of Anaesthetists. (2020) Aide-memoire. Nasogastric tube (NGT) placement checks before first use in critical care settings during the COVID-19 response.

Borsci, S., Buckle, P., Huddy, J., Alaestante, Z., Ni, Z. and Hanna, G.B. (2017) Usability study of pH strips for nasogastric tube placement. PLoS ONE, 12 (11), e0189013.

Bradford Institute for Health Research. (2012) A behaviour change approach to the implementation of nasogastric tube placement patient safety guidance: NPSA alert safety improvement project summary report for the Leeds Teaching Hospitals Patient Safety Group and Trust Board.

British Institute of Radiology, Society and College of Radiographers and The Royal College of Radiologists, Institute of Physics and Engineering in Medicine, Public Health England. (2020) IR(ME)R Implications for clinical practice in diagnostic imaging, interventional radiology and diagnostic nuclear medicine.

British Standards Institution. (2020a) BSI transitions In Vitro Diagnostic Regulation (IVDR) [Online]. Available at https://www.bsigroup.com (Accessed 8 October 2020).

British Standards Institute. (2020b) email to National Investigator, HSIB, 8 October.

Burban, C. and Jackson, P. (2017) A Framework for investigating fatigue. Clockwork Research.

Carayon, P., Wetterneck, T. B., Rivera-Rodriguez, A. J., Schoofs Hundt, A., Hoonakker, P., Holden, R. and Gurses, A. P. (2013) Human factors systems approach to healthcare quality and patient safety. Applied Ergonomics, 45 (1), 14-25.

Care Quality Commission. (2016) Learning from serious incidents in NHS acute hospitals. A review of the quality of investigation reports.

Care Quality Commission. (2018a) Opening the door to change NHS safety culture and the need for transformation.

Care Quality Commission. (2018b) Radiology review. A national review of radiology reporting within the NHS in England.

Cumberlege, B. J. (2020) First do no harm. The report of the Independent Medicines and Medical Devices Safety Review.

Department of Health and Social Care. (2017) The Ionising Radiation (Medical Exposure) Regulations 2017.

Department of Health and Social Care. (2018) Guidance to the Ionising Radiation (Medical Exposure) Regulations 2017.

Drew, T., Vo, M. L. H. and Wolfe, J. M. (2013) The invisible gorilla strikes again: sustained inattentional blindness in expert observers. Psychological Science, 24 (9), 1848-1853.

Earley, T. (2019) Improving safety with nasogastric tubes: a whole-system approach. Nursing Times [online], 115 (12), 50-51.

The Faculty of Intensive Care Medicine and Intensive Care Society. (2019) Guidelines for the provision of intensive care services [Online]. Available at https://www.rcslt.org/-/media/docs/clinical-guidance/critical-care-gpics-v2.pdf

Fan, E. M. P., Tan, S. B. and Ang, S. Y. (2017) Nasogastric tube placement confirmation: where we are and where we should be heading. Proceedings of Singapore Healthcare, 26 (3), 189-195.

Fernandez, R. S., Pak-Chun Chau, J., Thompson, D. R., Griffiths, R. and Lo, H-S. (2010) Accuracy of biochemical markers for predicting nasogastric tube placement in adults: a systematic review of diagnostic studies. International Journal of Nursing Studies, 47 (8), 1037-1046.

Francis, R. (2013) Report of the Mid Staffordshire NHS Foundation Trust Public Inquiry.

Gask, L., Coupe, N. and Green, G. (2019) An evaluation of the implementation of cascade training for suicide prevention during the ‘Choose Life’ initiative in Scotland – utilizing Normalization Process Theory. BMC Health Services Research, 19 (1), 588.

GOV.UK. (2020) Notified bodies for medical devices [Online]. Available at https://www.gov.uk/government/publications/notified-bodies-for-medical-devices/notified-bodies-for-medical-devices (Accessed 8 October 2020).

Gureje, O., Abdulmalik, J., Kola, L., Musa, E., Yasamy, M. T. and Adebayoet, K. (2015) Integrating mental health into primary care in Nigeria: report of a demonstration project using the mental health gap action programme intervention guide. BMC Health Services Research, 15 (1), 242.

Hanna, G., Phillips, L., Priest, O. and Ni, Z. (2010) Improving the safety of nasogastric feeding tube insertion. Developing guidelines for the safe verification of feeding tube position – a decision analysis approach. A report for the NHS Patient Safety Research Portfolio.

Health and Safety Executive. (1974) Health and Safety at Work etc. Act 1974.

Health Education England. (2020) About the Ionising Radiation (Medical Exposure) Regulations programme [Online]. Available at https://www.e-lfh.org.uk/programmes/ionising-radiation-medical-exposure-regulations/ (Accessed 10 September 2020).

Healthcare Safety Investigation Branch. (2018) Design and safe use of portable oxygen systems.

Healthcare Safety Investigation Branch. (2019) Failures in communication or follow-up of unexpected significant radiological findings.

Healthcare Safety Investigation Branch. (2020) Interim bulletin. Placement of nasogastric tubes.

Ishida, N., Kaneko, M. and Allada, R. (1999) Biological Clocks. Proceeding of the National Academy of Sciences of the United States of America, 96 (16), 8819- 8820.

Jones, Barry J M, British Association for Parenteral and Enteral Nutrition. (2020) A position paper on nasogastric feeding tube safety. “Time to put patient safety first”.

Law, R. and Kelly, S. (2011) Reducing the risk of nasogastric intubation ‘Never Event’: a radiographer led service development. Imaging and Therapy Practice, 14, 10-12.

Leape, L., Donald, B. and Bates, D. (2002) What practices will most improve safety? JAMA The Journal of the American Medical Association, 288 (4), 501-507.

Mack, A. (2003) Inattentional blindness: looking without seeing. Current Directions in Psychological Science, 12 (5), 180-184.

Medicines and Healthcare products Regulatory Agency. (2020) About Yellow Card [Online]. Available at https://yellowcard.mhra.gov.uk/the-yellow-card-scheme/ (Accessed 10 February 2020).

Medicines and Healthcare products Regulatory Agency. (2019), email to National Investigator, HSIB, 15 November.

Metheny, N. A., Krieger, M. M., Healey, F. and Meert, K. L. (2019) A review of guidelines to distinguish between gastric and pulmonary placement of nasogastric tubes. Heart and Lung: the Journal of Critical Care, 48 (3), 226-235.

Monk, T. (1988) Shiftwork: determinants of coping ability and areas of application. Advances in the Biosciences, 73, 195-207. National Institute for Health and Care Excellence. (2006) Nutrition support for adults: oral nutrition support, enteral tube feeding and parenteral nutrition.

National Institute for Health and Care Excellence. (2016) CORTRAK 2 Enteral Access System for placing nasoenteral feeding tubes. Medtech innovation briefing [MIB48] [Online]. Available at https://www.nice.org.uk/advice/mib48 (Accessed 24 July 2020).

National Patient Safety Agency. (2005a) Reducing the harm caused by misplaced nasogastric feeding tubes.

National Patient Safety Agency. (2005b) Information for parents and carers of babies with nasogastric feeding tubes under the care of neonatal units.

National Patient Safety Agency. (2011) Reducing the harm caused by misplaced nasogastric feeding tubes in adults, children and infants.

National Patient Safety Agency. (2012) Harm from flushing of nasogastric tubes before confirmation of placement.

NHS England and NHS Improvement. (2019) The NHS Patient Safety Strategy. Safer culture, safer systems, safer patients.

NHS England. (2013) Placement devices for nasogastric tube placement DO NOT replace initial placement checks. NHS England. (2019) Introducing National Patient Safety Alerts and the role of the National Patient Safety Alerting Committee. [Online] Available at https://www.england.nhs.uk/patient-safety/national-patient-safety-alerting-committee

NHS Improvement. (2016a) Nasogastric tube misplacement: continuing risk of death and severe harm.

NHS Improvement. (2016b) Resource set. Initial placement checks for nasogastric and orogastric tubes.

NHS Improvement. (2018a) Recommendations from National Patient Safety Agency alerts that remain relevant to the Never Events list 2018.

NHS Improvement. (2018b) Revised Never Events policy and framework.

Nursing and Midwifery Council. (2015) The Code. Professional standards of practice and behaviour for nurses, midwives and nursing associates.

Nursing and Midwifery Council. (2018a) Future nurse: standards of proficiency for registered nurses.

Nursing and Midwifery Council. (2018b) Realising professionalism: standards for education and training. Part 1: Standards framework for nursing and midwifery education [Online]. Available at https://www.nmc.org.uk/globalassets/sitedocuments/education-standards/education-framework.pdf (Accessed 1 October 2020).

Nursing and Midwifery Council. (2019) Revalidation [Online]. Available at http://revalidation.nmc.org.uk/ (Accessed 20 November 2020).

RAIQC. (2020) RAIQC [Online]. Available at https://www.raiqc.com (Accessed 23 November 2020).

Roe, G., Harris, K. M., Lambie, H. and Tolan, D. J. M. (2017) Radiographer workforce role expansion to improve patient safety related to nasogastric tube placement for feeding in adults. Clinical Radiology, 72 (6), 518.e1-518.e7.

Roe, G., Lambie, H. and Tolan, D. (2019) Acceptability of a new practice development for radiographers focussed on reducing ‘Never Events’ related to nasogastric feeding tubes in adult patients. Radiography, 25 (3), 235-240.

Rowat, A. M., Graham, C. and Dennis, M. (2018) Study to determine the likely accuracy of pH testing to confirm nasogastric tube placement. British Medical Journal Open Gastroenterology, 5 (1), e000211.

Royal College of Nursing, General Chiropractic Council, General Osteopathic Council, Chartered Society of Physiotherapy, NHS Alliance, The Royal College of Radiologists and Society and College of Radiographers. (2008) Clinical imaging requests from non medically qualified professionals.

The Royal College of Radiologists. (2018) Standards for interpretation and reporting of imaging investigations. Second edition.

The Royal College of Radiologists. (2019a) Picture archiving and communication systems (PACS) and guidelines on diagnostic display devices.

The Royal College of Radiologists. (2019b) The Quality Standard for Imaging: statements, rationales and criteria. QSI 2019. Available at https://www.rcr.ac.uk/sites/default/files/qsi_2019_final.pdf

The Royal College of Radiologists, (n.d). Radiology FAQs [Online]. Available at https://www.rcr.ac.uk/public-and-media/common-medical-terms/radiology-faqs#radio

The Society and College of Radiographers, (n.d.). About radiography [Online]. Available at https://www.sor.org/about-radiography/what-radiography-who-are-radiographers (Accessed 1 December 2020)

The Society and College of Radiographers. (2020) email to National Investigator, HSIB, 1 December.

Saddington, H. (2018) Nasogastric (NG) and nasojejunal (NJ) feeding tubes – policy for insertion and management in adult patients (excludes paediatrics and neonates) [Online]. Available at https://www.sfh-tr.nhs.uk/media/8328/nasogastric-ng-and-nasojejunal-nj-feeding-tubes-policy-for-the-insertion-and-management-in-adult-patients.pdf (Accessed 27 July 2020).

Salas, E. and Driskell, J. E. (2016) Stress and Human Performance. Abingdon (Oxfordshire): Routledge.

Sellers, C. K. (2012) False-positive pH aspirates after nasogastric tube insertion in head and neck tumour. British Medical Journal Case Reports, bcr2012006591.

Stanton, N.A., Salmon, P.M., Rafferty, L.A., Walker, G.H., Baber, C., Jenkins, D.P. (2013). Human Factors Methods. A Practical Guide for Engineering and Design. Ashgate Publishing Ltd. Farnham. [1] International Ergonomics Association. (2019). What is Ergonomics? Available at https://www.iea.cc/whats/index.html

Svendung, J and Rasmussen, J. (2002) Graphic representation of accident scenarios: mapping system structure and the causation of accidents. Safety Science 2002; 40: 397-417.

Taylor, N., Lawton, R., Moore, S., Craig, J., Slater, B., Cracknell, A., Wright, J. and Mohammed, M. A. (2014) Collaborating with front-line healthcare professionals: the clinical and cost effectiveness of a theory based approach to the implementation of a national guideline. BMC Health Services Research, 14 (648).

Taylor, N., Lawton, R., Slater, B. and Foy, R. (2013) The demonstration of a theory-based approach to the design of localised patient safety interventions. Implementation Science, 8 (123).

Taylor, S. and Clemente, R. (2005) Confirmation of nasogastric tube position by pH testing. Journal of Human Nutrition and Dietetics, 18 (5), 371-375.

Toft, P. B. (2015) External Review of ‘Never Events’ that occurred at Oxford University Hospitals NHS Trust during the period 13 September 2013 to 26 March 2015.

The Trust. (2015) Initiation of naso-gastric tube feeding.

The Trust. (2018a) Safe insertion and management of a naso-gastric tube.

The Trust. (2018b) Initiating nasogastric feeding in critical care. The Trust. (2019) Post incident rapid review – StEIS standard report template.

Wagstaff, A. and Sigstad Lie, J-A. (2011) Shift and night work and long working hours – a systematic review of safety implications. Scandinavian Journal of Work, Environment and Health, 37 (3), 173-185.

World Health Organization. (2020a) Coronavirus [Online]. Available at https://www.who.int/health-topics/coronavirus#tab=tab_1 (Accessed 29 June 2020).

World Health Organization. (2020b) Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations [Online]. Available at https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations (Accessed 29 June 2020).

10 Endnotes

[1] The four criteria for confirming NG placement in X-ray are: Does the tube path follow the oesophagus/avoid the contours of the bronchi? Does the tube clearly bisect the carina or the bronchi? Does it cross the diaphragm in the midline? Is the tip clearly visible below the left hemi-diaphragm?

[2] The length of the NG tube is estimated using the ‘NEX’ measurement (nose, ear, xiphisternum). The exit port of the NG tube is placed at the tip of the nose, the tube is extended across to the earlobe and then down to the xiphisternum and a note is made of the measurement. This measurement is only an estimate. The NG tube is then inserted to the NEX measurement or just beyond. The position of the NG tube may need to be adjusted to enable gastric aspirate to be collected (plus or minus 10%). If confirmation of tube placement is achieved by testing the pH of gastric aspirate, the tube is secured and a note is made of the tube length.

[3] pH in the ‘safe range’ of 1 to 5.5 can be used as the first-line test to exclude placement in the respiratory tract. The normal human stomach has a pH of approximately 1 to 3 in an empty stomach and approximately 4 to 5 after food has been eaten. Patients on acid-reducing medication may have a stomach pH level of 6 or above The pH in healthy lungs is between 7.38 and 7.42 (NHS Improvement, 2016b).

[4] A pneumothorax is a collection of air in the chest outside the lung that causes the lung to collapse. The likely cause of a pneumothorax is a recognised complication of the central venous catheter insertion.

[5] Level of consciousness/arousal is recorded using a standard sedation score. The Richmond agitation-sedation scale (RASS) is a 10-point scale varying from -5 to +4 with a score of 0 being a calm and alert patient. Patients scoring -4 or -5 being comatose by definition.

[6] Ventilator acquired pneumonia (VAP) is a lung infection that can develop when critically ill people have had a breathing tube inserted and are on a ventilator to support their breathing.

[7] Tazocin is an antibiotic that is used to treat serious bacterial infections, including infection in the lungs.

[8] The national codes for levels of critical care are as follows:

Level 0 Patients whose needs can be met through normal ward care in an acute hospital.

Level 1 Patients at risk of their condition deteriorating, or those recently relocated from higher levels of care, whose needs can be met on an acute ward with additional advice and support from the critical care team.

Level 2 Patients requiring more detailed observation or intervention including support for a single failing organ system or post-operative care and those ‘stepping down’ from higher levels of care.

Level 3 Patients requiring advanced respiratory support alone or monitoring and support for two or more organ systems. This level includes all complex patients requiring support for multi-organ failure.

[9] Existing national guidance states CORTRAK must never be used to replace X-ray or pH confirmation.

[10] An in vitro medical device is defined as “any medical device which is a reagent, reagent product, calibrator, control material, kit, instrument, apparatus, piece of equipment, software or system, whether used alone or in combination, intended by the manufacturer to be used in vitro for the examination of specimens, including blood and tissue donations, derived from the human body…” (British Standards Institution, 2020a)

[11] A notified body, in the European Union, is an organisation that has been designated by a member state (the designating authority) to assess whether manufacturers and their medical devices meet the requirements set out in legislation. The MHRA is the designating and competent authority in the UK (GOV.UK, 2020).

Providing feedback and comment on HSIB reports

At HSIB we welcome feedback on our investigation reports. The best way to share your views and comments is to email us at enquiries@hsib.org.uk

We aim to provide a response to all correspondence within five working days.

This document, or parts of it, can be copied without specific permission providing that the source is duly acknowledged, the material is reproduced accurately, and it is not used in a derogatory manner or in a misleading context.

www.hsib.org.uk/tell-us-what-you-think