Key Concepts in Human Factors and Ergonomics

In this article, Dr Fiona Kelly, Consultant Anaesthetist and Intensivist at Royal United Hospitals Bath, and lead of the Difficult Airway Society Human Factors Group, explains some the key concepts surrounding Human Factors and Ergonomics (HFE) and shares some examples that are relevant for safe airway management. Later in this activity, we will use these concepts to revisit the case of Elaine Bromiley, which was presented in the previous step.

Human factors and ergonomics is a scientific discipline that aims to make it easy to do the right thing, and difficult or ideally impossible to do the wrong thing. The terms ‘human factors’ and ‘ergonomics’ essentially mean the same thing and can be used interchangeably: the modern phrase to use is ‘human factors and ergonomics’ or HFE.

HFE are important in airway management as humans, by their very nature, will inevitably make mistakes, however well trained, conscientious and hard-working we are. HFE aims to ‘design out’ the chances of an error occurring in the first place, and, if an error does occur, of putting barriers in place to prevent that error progressing to patient harm [1].

HFE have been used successfully in all other safety critical industries to improve safety, including off-shore oil, nuclear power, aviation, construction, rail travel and the military. Healthcare is the final sector to be targeted, and indeed the Chartered Institute of Ergonomics and Human Factors (CIEHF) launched their HFE in healthcare white paper in 2018: this set out the importance of HFE in healthcare and how HFE might be embedded into healthcare over the coming years [2].

The Airway Spider

Many aspects of HFE are relevant to airway management, and these can easily be described using the “Airway Spider” model [3], each leg of the spider representing one letter of the mnemonic ARACHNID.

Airway Spider

D = Design

The most important aspect is design of safe systems and safe working practices. Such design principles can be used effectively in healthcare today. For example, older style anaesthetic machines have an oxygen rotameter which is bigger than the nitrous oxide and air rotameters: it sits proud from the others, is always on the left and has ridges around its edge:

Rotameters on anaesthetic machine

Other examples of good design include always placing a video laryngoscope screen on the opposite side of the bed to the anaesthetic assistant, so that all members of the team can see the screen easily.

videolaryngoscope ergonomics

Standardisation of equipment is also important, with an example in airway management being airway trolleys arranged in the same format in different areas around a hospital and ideally around the country. We will discuss airway trolleys design in Week 2 of Airway Matters.

A = Algorithms

Both designing algorithms using HFE expertise as well as printing algorithms out in colour and having them available in anaesthetic rooms so that they can be referred to in an emergency if needed is useful. An example of well-designed algorithms in airway management are the DAS 2015 Difficult Intubation Guidelines, which have prompts for the team to ‘call for help’, ‘declare a failed intubation’, ‘stop and think’ and ‘invite ideas from the team.’ You will learn more about these guidelines in Week 2.

DAS call for help ©Difficult Airway Society

R = Resilience and worker wellbeing

Resilience is the ability to bounce back from difficulty [4]. Many strategies exist to improve our team resilience, at a National, Trust and Departmental level, as well as strategies to improve our own personal resilience. You may be interested to read this article [5], which explains in more details the concept of resilience.

A = Cognitive Aids

These are educational materials designed to improve the management of an emergency. An example in difficult airway management would be the Vortex model [6] from Australia for managing a ‘Can’t Intubate, Can’t Oxygenate (CICO)’ situation that will be discussed in Week 2.

©Nicholas Chrimes - The Vortex approach

C = Checklists

Checklists are proven to improve adherence to an algorithm, an example would be the intubation checklist from the DAS Intubation Guidelines for the Critically Ill; these will be discussed in Week 4.

H = Handover Tools

Handover Tools aim to improve clarity of transfer of information within members of a team. Examples include:
• SBAR (Situation, Background, Action, Recommendation)
• Traffic light handover tool (Red emergencies, Amber assists, Green queries) [7]
• SNAPPI tool (Stop, Notify, Assessment, Plan, Prioritise, Invite ideas)[8]

N = Non-technical skills (NTS)

These are well described by the Anaesthetists’ Non-Technical Skills (ANTS) Framework [9] which include team-work and communication, situation awareness, task management and decision making. Other important aspects include flattening the hierarchy or reducing the authority gradient, and encouraging staff to speak up if they feel that patient safety is compromised. In addition, leadership and followership, delegation and prioritisation and coping with distractions are all very important aspects of NTS.


I = Incident reporting and investigation.

This is ideally done by independent teams with HFE training, with the aim of learning from an event creating a just culture, as we will discuss in Week 5. Such teams would use a specialist HFE investigative tool, such as the Yorkshire Framework[10].

So this is a summary of the various aspects of HFE as relevant to difficult airway management. Putting these together and looking at the role that HFE might play in an airway emergency, it’s useful to look at error chains.

Error Chains

Often, in an emergency, there are multiple things all happening at once and events don’t always follow each other in a linear fashion, as an error chain suggests. However, error chains can help to explain the concepts well and how the various aspects of HFE play a role in airway emergencies.

Looking at an error chain, there are three different types of error at the top:

Systems errors, also known as latent errors
Human errors, also known as active failures
Catalyst events, also known as coincidental events

Error chain

If two of these three types of errors are present at the same time, then an unsafe situation is created. If this is then combined with poor non-technical skills and poor situation awareness within the team, then a point of no return is reached and an adverse event, such as an airway emergency, occurs.

In the past the investigation of many airway critical incidents has tended to scrutinise the actions of those clinicians involved in immense detail, when in fact it would have been better to look at the entire error chain and the events ‘further upstream’ from the final adverse event.

Not only would looking at the entire error chain and all relevant factors prevent those clinicians suffering even more distress and anguish than they might already be experiencing, it would enable the investigators to really get to understand the causative factors and take steps to ‘design out’ the error(s) to prevent them occurring again.

Error Chain - Design out

Non-technical skills act in the centre of the error chain and at the top as shown in the following diagram:

Error Chain non-technical skills

Much team training is carried out with the aim of improving non-technical skills, however, if that team is then placed back into an imperfect system, with system errors and/or catalyst errors still present, then the chance of the same error occurring is high. Many would say that healthcare is relying on incredibly high levels of personal performance every day to maintain patient safety, and that incorporating HFE expertise into our day to day working has the potential for us to be less reliant on such high levels of personal performance and improve airway safety.

Identifying and addressing HFE is vital to improve safety in healthcare. We are looking forward to hearing about some of your experiences in this area in the next step.


  1. Clinical Human Factors Group
  2. CIEHF Healthcare White Paper
  3. Kelly FE, Bahagrath R, McNarry A. The ‘airway spider’: an educational tool for teaching human factors and ergonomics in airway management. Anaesthesia 2018; 73(2): 257-258
  4. Medical Trauma and Resilience Training
  5. Kelly FE, Osborn M, Stacey M. Resilience in anaesthesia and intensive care medicine – learning lessons from the military. Anaesthesia 2019. Epub
  6. The Vortex Approach
  7. MacDougall-Davis S, Kettley L, Cook TM. The ‘go-between’ study: a simulation study comparing the ‘Traffic Light’ and ‘SBAR’ tools as a means of communication between anaesthetic staff. Anaesthesia 2016, 71, 764–772
  8. Weller JM, Boyd M, Frengley, Improving team information sharing with a structured call-out in anaesthetic emergencies: a randomized controlled trial, British Journal of Anaesthesia 2014. 112 (6), 1042–1049
  9. Flin R, Patey R, Glavin R, Maran N, Anaesthetists’ non-technical skills. British Journal of Anaesthesia 2010. 105(1): 38–44
  10. Lawton R, McEachan RR, Giles SJ, Sirriyeh R, Watt IS, Wright J. Development of an evidence-based framework of factors contributing to patient safety incidents in hospital settings: a systematic review. BMJ Qual Safety 2012. 21: 369-80
  11. Report of the enquiry on the death of Elaine Bromiley

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This article is from the free online course:

Airway Matters

UCL (University College London)