The rationale for using a difficult airway algorithm
The Difficult Airway Society (DAS) publishes evidence-based, peer-reviewed guidelines for unanticipated failed intubation.1 These guidelines outline relatively simple airway skills, several of which are listed as core competencies for trainees by CICM, ACEM and ANZCA, and all of which are covered in the CCAM course.
The Vortex approach is a cognitive aid which moves the intubator between three broad airway management strategies: oxygenation via a face mask, supraglottic airway device (SAD) or tracheal tube. It recommends that when an optimal attempt has failed using each technique sequentially, an emergency surgical airway is performed.
Both of these algorithms are designed to enhance situational awareness (where are we now?) and facilitate decision making (what shall we do next?), in an attempt to prevent the intubator from making multiple attempts, potentially making a difficult situation worse. This ‘fixation’ on one method, leading to a failure to progress to the next one, and eventually to a surgical airway, has long been recognised to be a problem in difficult airway management.2 An analysis of 2833 tracheal intubations in the ICU and ED showed that, when there were more than two attempts at laryngoscopy, the incidence of several harmful complications rose markedly: hypoxemia (70% vs 11.8%); regurgitation of gastric contents (22% vs 1.9%); aspiration of gastric contents (13% vs 0.8%); bradycardia (21 % vs 1.6%); and cardiac arrest (11% vs 0.7%).3
The UK Royal College of Anaesthetists Fourth National Audit Project (NAP 4) suggested that this phenomenon is still causing morbidity and mortality, despite the widespread use of algorithms. In the audit, there were several incidents where multiple attempts at laryngoscopy resulted in a ‘can’t intubate, can’t oxygenate’ scenario in patients in whom ventilation was initially possible, and several others where an emergency surgical airway was not performed when indicated.4-6
The DAS and Vortex algorithms are relatively simple and straightforward, which makes them easy to remember. However, it is clear that clinicians still find it difficult to progress through these algorithms in stressful situations. This is due to a multitude of factors, such as the high stakes involved, but is also due to the fact that failed intubation is a relatively infrequent event. As a result, the skills and behaviours required to follow an airway algorithm to its successful conclusion need to be practised and rehearsed.
Some of the practical skills involved (such as cricothyroidotomy) are rarely used in everyday practice and consequently, various authorities have recommended that they be taught in a simulator setting. Furthermore, the acquisition of simple airway skills does not require a full high-fidelity simulator: for example, there is good evidence that practice on a simple model bronchial tree helps trainees gain the manual dexterity required for fibre optic bronchoscopy in real patients.7
However, technical skills are only part of the story. As a team of clinicians, we also need to be trained in the attitudes and behaviours needed to manage a crisis. These traits are variously known as ‘non-technical skills’ or ‘human factors’ and training in this area often termed ‘Crisis Resource Management’.
The tragic case of Elaine Bromiley gives us compelling evidence for the importance of human factors and in health care. This 37 year-old mother died during anaesthesia for routine surgery in 2005 when the Difficult Airway Society guidelines were not followed when it proved difficult to intubate her trachea or ventilate her lungs. The independent review which followed Elaine’s death concluded that the technical skills of the anaesthetists concerned, facilities and staffing levels were all more than adequate and that human factors such as poor situational awareness, decision making and communication skills, and a lack of adherence to a difficult airway algorithm were responsible for her death.8 Elaine Bromiley’s husband, Martin, an airline pilot and a ‘human factors’ trainer for the airline industry, has responded to this tragedy by founding the Clinical Human Factors Group, an independent organisation that promotes awareness of and training in non-technical skills (www.chfg.org).
Please watch Martin’s video below for an account of Elaine’s case, and how Martin suggests we respond.