Chapter 36 – Human Factors in Airway Management

Abstract

Human factors can be defined as the science of understanding of interactions among humans and other elements of a system, and how they can be adapted to improve performance and safety. Human factors issues were present in 40% of the cases of major complications in airway management in NAP4. Human factors issues can be considered in terms of ‘threats’ and ‘safeguards’. Threats increase the likelihood of the occurrence of an error that results in patient harm while safeguards help prevent this. Threats and safeguards in relation to human factors in airway management refer not only to ‘non-technical skills’ (e.g. situation awareness, teamwork) but also many other factors such as procedures, staffing and the physical environment in which airway management is conducted. Proper attention to human factors related issues contributes to both the prevention and effective management of airway emergencies and requires that these issues are considered as part of an integrated approach at the level of the individual, team, environment and organisation as part of routine airway care – not only when an emergency arises.

Chapter 36 Human Factors in Airway Management

Mikael Rewers and Nicholas Chrimes

What Is Meant by ‘Human Factors’?

Human factors (ergonomics) is the scientific discipline concerned with the understanding and optimising of interactions between humans and other elements of a system. It involves considering the individual, team, environmental and organisational factors that influence overall system performance (Table 36.1). It is as concerned with augmenting the human contribution to success as it is with protecting against the potential to contribute to error.

Table 36.1 Common human factors in airway management

CATEGORY	FACTORS	THREATS	SAFEGUARDS
Individual
Situation awareness (also at team level)	Attention/vigilance, perception, problem detection, memory, recognition, comprehension, anticipation	Distraction, lack of gathering all cues, distorted time perception, memory lapse, inadequate knowledge, inability to apply knowledge into context, poor communication, lack of ‘shared mental model’, assumption, fixation	Continuous systematic scanning, cross-checking information, establishing/maintaining a ‘shared mental model’, declaring a situation, ‘thinking ahead’
Decision making (also at team level)	Identify available options, judgement to select and implement, re-evaluation	Poor situation awareness, poor judgement, failure to re-evaluate	Cognitive aids, considering advantages/disadvantages, re-evaluating after each airway attempt
Personality	Confidence, insight, willingness to act	Overconfidence, denial, pride, guilt, diffidence	Humility, willingness to ask for help, recognition of own limitations, reflection
Technical	Competence, manual dexterity	Inadequate skills, inadequate airway assessment	Expertise, experience, supervision, training
Performance-shaping factors	Stimulation, mood, satiety, alertness, health, motivation, interest	Stress, hunger, fatigue, illness/injury, apathy/improper motivation	Calm, refreshed, sleep hygiene, alert, engaged
Team
Behavioural	Coordination/leadership, role allocation, teamwork, communication	Ineffective coordination/teamwork, role ambiguity, unclear communication, multiple ambiguous/conflicting terminologies	Effective coordination/leadership, clear roles, cooperative teamwork, consultation, calling for help, team brief, names, closed loop communication, prompting, common goal, ‘speaking up’, ‘mini team time-out’
Social	Interactions, familiarity	Conflict, awkwardness, intimidation	Harmonious relationship, understanding each other’s ideas or concerns
Work preparation	Planning, preparing	Limitation in strategies/plans, lack of available time to plan	Strategy with contingency plans, checklists, taking only a few seconds to plan can be beneficial for decision- making and teamwork
Environmental
Equipment	Design, availability, access, maintenance, function	Inconsistent storage locations, clutter, poor user interface, design defects, equipment faults, inappropriate alarm settings or alert signals	Suitability, proximity, visibility, readiness, well-designed equipment/alarms
Workspace	Size, layout	Crowding, obstructed views, poor equipment position	Adequate space, optimal layout
Ambience	Lighting, sound, temperature	Inadequate lighting, noise	‘Sterile cockpit’, ‘Focus’
Organisational
Job factors	Task complexity, staffing, workload	Task difficulty, inadequate staffing, excessive workload, time/production pressure, night shift	Assistance/backup
Policies/Procedures	Guidelines, protocols, reporting, standards	Lack of incident reporting or multi-professional morbidity/mortality meetings	Learning through multi-professional morbidity/mortality meetings
Training/Supervision	Programmes	Lack of training, inadequate supervision	Education, feedback, supervision, case discussion
Culture	Management, norms, patient safety	Judgemental culture, skewed norms, ‘waiting for errors to occur’	Non-judgemental culture, praise colleagues for good work, resilience

This chapter provides an overview of the principles of human factors in relation to airway management.

How Much Do Human Factors Impact on Airway Management Outcome?

Human error is implicated in up to 80% of anaesthetic incidents. The 4th National Audit Project (NAP4) in the United Kingdom concluded that human factor-related issues such as poor judgement, communication and teamwork contributed to 40% of major complications in airway management and were deemed to be major factors in 25% of these cases. In a follow-up study, Flin et al. identified an average of four contributing human factors per NAP4 case; the most frequent were failures to anticipate, wrong decision, task difficulty, inappropriate staffing, time pressure, tiredness, hunger, stress, poor communication and limitations in competence. The study also revealed protective factors such as good teamwork and effective communication. Overall, the contribution of human factors related issues to patient harm during airway management is at least as important as that resulting from technical issues.

Stop and think: is there any data on airway management outcomes in your department? What does the data show?

Why Do Human Factor-Related Adverse Events Occur in Airway Management?

Error Triggers

Human errors are inevitable, no matter how well trained and motivated an individual is.

‘Threats’ refer to aspects of the individual, team, work environment or organisation that can influence work performance by increasing the chance of an error (Tables 36.1 and 36.2). Threats will not inevitably lead to errors, nor will errors always result in adverse consequences. For the most part, additional contributing elements are necessary for an error to evolve into an adverse event. Small errors can trigger significant adverse outcomes and vice versa.

Table 36.2 Selected ‘threats’ from Table 36.1 with examples

CATEGORY	THREATS	EXAMPLES OF RESULTING ERRORS IN AIRWAY MANAGEMENT
Individual
Situation awareness	Distorted time perception	Distorted time perception leads to team failing to recognise how long patient has been hypoxic
	Assumption	Assumption that lack of etCO₂ trace or low SpO₂ are errors
	Fixation	Repeated attempts at intubation, prolonged hypoxia, airway trauma and potential precipitation of CICO
Personality	Denial, pride, guilt	•Refusal to acknowledge oxygenation is not occurring
		•Trying to prove you can intubate the patient
		•Clinician belief that they should have predicted or have precipitated the difficult airway
Technical	Inadequate skills	•Reluctance to perform front of neck airway rescue or awake flexible optical intubation
	Inadequate skills	•High failure rate of front of neck airway rescue techniques
	Inadequate airway assessment	•Impaired situation awareness of airway risk
	Inadequate airway assessment	•Diminished ability to deal with airway challenges
Performance-shaping factors	Stress, hunger, fatigue, illness/injury, apathy/improper motivation	•May act as a distraction which impairs situation awareness
Performance-shaping factors		•May promote taking shortcuts e.g. inadequate airway assessment, planning, positioning or preoxygenation
Team
Behavioural	Ineffective coordination/teamwork, role ambiguity, unclear communication	•Duplication of tasks combined with failure to allocate other tasks: multiple people focused on getting emergency airway trolley, no one watching monitors
Behavioural	Multiple ambiguous/conflicting terminologies	E.g. surgical airway, eFONA, CICO rescue, infraglottic rescue; these terms may not be mutually understood by all team members leading to confusion and delays in execution
Social	Conflict, awkwardness, intimidation	Failure to mention important information: e.g. ‘There’s no etCO₂ trace’, ‘The patient is cyanotic’, or ‘The SpO₂ has been <80% for 2 mins’
Environmental
Equipment	Inconsistent storage locations, clutter	Difficulty locating airway rescue or CICO equipment
Equipment	Poor user interface, design defects, equipment faults, inappropriate alarm settings or alert signals	Difficulty obtaining/interpreting information: misinterpreting airway pressure waveform or etO₂ waveform as etCO₂ trace Alarms set too broadly fail to alert team to hypoxia (trigger too late) If alarm settings are too sensitive clinicians develop ‘alarm fatigue’ and ignore them delaying recognition of a crisis Inconsistent tone modulation with SpO₂ change between different types of monitors Tone modulation on SpO₂ monitor switched off
Workspace	Crowding, obstructed views, poor equipment position	•Lack of visibility of monitors: failure to recognise falling SpO₂, lack of etCO₂ trace or other clinical abnormalities
Ambience	Noise	Impaired communication, difficulty hearing SpO₂ tone modulation or alarms
Organisational
Job factors	Excessive workload, time/production pressure	Failure to develop an airway strategy, avoidance of awake flexible optical intubation, inadequate preoxygenation
Training/Supervision	Lack of training, inadequate supervision	•Inexperienced staff (airway operators & assistants) with poor decision making, inadequate airway skills
Culture	Skewed norms	Acceptance of high risk behaviours, failure to assess airway, failure to plan
	‘Waiting for errors to occur’	Only allows safety improvements to be implemented retrospectively (underestimation of risk)

CICO: cannot intubate, cannot oxygenate, FONA: front of neck airway

Table 36.3 Common human factor-related errors seen in airway crises

ACTIONS	RESULTS
Inadequate attempts at upper airway rescue: omission of optimisations or entire techniques	Unnecessary front of neck airway rescue
Fixation on intubation: to the exclusion of upper airway techniques, airway trauma	Precipitating CICO, delayed CICO rescue
Poor decision-making when oxygenation is present, ignoring options to wake or convert, repeated instrumentation	Precipitating CICO
Fixation on upper airway techniques: failure to declare CICO and move to front of neck airway techniques	Delayed CICO rescue

CICO: cannot intubate, cannot oxygenate

Stop and think: what threats can you identify in your clinical practice? How will you address these?

Stress

An airway crisis can be a high-stakes, time-critical situation. Excessive stress compromises the cognitive, communication and technical skills of clinicians, which may diminish their ability to resolve the crisis. Although the susceptibility of different individuals to performance impairment due to stress will vary, all clinicians will suffer from this phenomenon, if the pressure exceeds their limits.

Stress-related cognitive impairment may lead to fixation, distorted time perception, impaired knowledge recall and impaired judgement. These issues may combine to lead even experienced clinicians to make fundamental errors, considered inconceivable in the non-stressed state.

Failure to ‘do the basics’ under pressure is a recognised problem in real-life airway emergencies. No preceding attempt was made to place a supraglottic airway device (SGA) in over half of the cases of emergency front of neck airway in NAP4. Some common human factor-related errors seen in airway crises are listed in Table 36.3.

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