An ambulance parked outside a hospital

Investigation highlights challenges when diagnosing ‘time-critical’ pulmonary embolism in the emergency department

by Communications team

Our latest report highlights the risk to patients from a pulmonary embolism (PE) being missed or not treated at the point they seek emergency care and focuses on learning to support clinical decision making.

The risk relating to the recognition of PE was identified in an earlier HSIB investigation. Although the majority of PEs are correctly identified and treated, we felt that the risk of serious harm or death, if missed, warranted further exploration. The investigation was then launched in early 2020, but due to the COVID-19 pandemic, much of our work was paused.

Once this investigation restarted, it was decided that an examination of serious incident investigation reports from across hospitals in England would inform the direction of the national investigation, rather than an individual case of patient care.

A consistent finding across the review of 14 serious incident reports completed by NHS trusts was that ‘incorrect’ decisions were being made in the diagnosis and treatment of PE. As a result, our national investigation focused on understanding the clinical decisions being made in emergency care and the role of the expert.


Although we did not investigate a specific patient safety incident, through the review, they learnt of the case of Martin, 51, who sadly died from a PE that was not identified. Martin went to his local emergency department (ED) after experiencing breathlessness and testing negative for COVID-19. Tests carried out in the ED included heart tracing, chest X-ray and blood tests which were all normal. A D-dimer blood test (used as part of the assessment of likelihood of PE) was planned but never carried out.

Martin’s case provided a real-life insight into the impact of decision making on patients and families. Our findings in this report were formed by using a specific methodology known as Applied Cognitive Task Analysis (ACTA).

This was the first time we had the opportunity to use this approach and it allowed an in-depth examination of decision making, analysing the cognitive elements of tasks. It considers how expertise support the undertaking of cognitive tasks and why such tasks may be difficult for novices. Our analysis included a knowledge audit, which involves interviews with staff to explore expertise using probing questions.

The investigation’s findings, informed by ACTA and other observations and interviews, emphasise the challenges, not only in terms of recognising PE in a timely way but also in ensuring, more generally, that ED staff are given the time and space to develop their expertise in a formal way.

Key findings

Key findings set out in the report include.

  • Recognising that a person may have a PE is challenging, particularly for less experienced staff and when the person’s signs and symptoms are non-specific or atypical.
  • Experts use different thought processes and show different behaviours when making decisions compared to more novice staff.
  • Staff asked for further guidance to be provided on the use of decision aids to support the diagnosis of PE.
  • Decision-making skills in healthcare are commonly developed through experience, without formal training or opportunities to practise making decisions.
  • Simulation-based learning has the potential to help staff acquire decision making skills more quickly.

The investigation acknowledges the pressure that exists within EDs, exacerbated by the pandemic and that decision making has always and continues to be affected by workload, workforce availability, and performance targets. We also recognise that the challenge in diagnosing a PE has been made more complex as symptoms of COVID and PE can be similar, and a patient can have both at the same time.

The report concludes with three safety recommendations and a series of safety observations focused on creating the conditions within which the NHS can support staff to develop decision-making skills and provide them with support to help them make difficult decisions in the challenging context of working in emergency care.

Dr Nick Woodier, National Investigator at HSIB says When reviewing serious incident reports, it was clear that there is continuing harm associated with delays to PE diagnosis and its treatment. The impact on patients and families can be devastating, as shown in Martin’s case. Healthcare staff can also feel greatly distressed if a PE is missed.

“We recognise the ever-present challenges faced by EDs, made worse by Covid-19. However, the data demonstrated the need to understand how diagnostic decisions are made, and how decision-making can be supported. All the clinical staff we interviewed as part of the investigation were welcoming, insightful and keen to share their experience, telling us what concerned them the most and where they think improvement could be made at a national level.

“The safety recommendations and observations we have made are intended to help the NHS support the long-term improvement of clinical expertise so that the decisions made in the emergency department lead to timely diagnosis of PE and ensure the best outcome for patients across the country.”

Read the report

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