Airway assessment/management paradigm - does a spectral or a binary approach fit better?

Abstract

Pandit's eloquent editorial has raised more questions concerning the place of airway assessment and it's relationship to difficult airway management, while advocating the validity of a binary approach to airway testing 1. Binary concepts are common in human thought as we have a tendency to perceive our environment as such, e.g. good or evil, guilty or not, dead or alive. They often provide an initial structure for human understanding by simplifying complex systems and allowing us to understand and communicate rapidly. However, steadfast adherence leads to blind spots in understanding and potential failure when dealing with real world complexities. If we adopt only a binary approach and fail to question further, we are in danger of not investigating the system fully and simply perpetuating the binary. Post-modernism fought binary thinking by advocating the creation of more multifarious models and theories to replace the binary approach and understand the complexity of the real world. However, the complete abolition of a binary approach and obtaining a full understanding of difficult airway assessment and management complexities may be well beyond the capabilities of many doctors exposed to airway management. Most of us retain and use our airway assessment techniques taught to us at an early stage of our career without a complete understanding of how they impact on our management. As Fyodor Dostoyevsky (in ‘Demons’ Chapter 2) said, “It seems, in fact, as though the second half of a man's life is made up of nothing, but the habits he has accumulated during the first half”. During our career, we accumulate a sum of experiences that provides us with an intuitive understanding of difficult airways and how they should be managed. Airway management skills are developed over time and through experience. The fundamental flaw of binary assessment is the likelihood that it leads to binary management. Pandit rightly suggests ‘regarding predictive tests as screening rather than diagnostic’. This places the battery of bedside testing in its correct place as the start of a clinical process upon which further testing, such as imaging nasopharyngoscopy, ultrasound and then airway management, is built. However, we disagree when he states, “…the “difficult airway” could and should be regarded as a syndrome, composed of very many individual rare diseases…there is little commonality between each of our rare airway diseases other than that they are not easy”. This seems to imply that a difficult airway classification is impossible to develop. However, categorising difficult airways remains key to better understanding and clear management strategies 2. Yentis 3 pointed out that the word ‘difficult’ is a subjective term in airway management, and may be influenced by several factors including: human factors; experience; location; patient factors; equipment; and time pressure 4. Such complex inter-relationships are not easily assessed with a binary approach. Relying purely on a screening test for management rather than further exploration of the possible pathology is likely to lead to management failure. He further stated: ‘The first problem is defining the problem’ 5. The current paradigm focuses the definition of the difficult airway on the management outcomes (i.e. failure is defined by number of attempts, use of specialised airway equipment and/or adverse outcomes such as arterial oxygen desaturation) rather than understanding airway morphology and pathology. Since other medical conditions and diseases are identified and classified based on the disease pathology rather than success or not of treatment modalities, why should a similar approach not apply to airway management? The cornerstone of medical care is the ‘diagnosis-management paradigm’. Teaching the assessment of normal and difficult airways should begin with an understanding of airway morphology 6-8, which then allows the clinician to tailor a specific treatment for each subclass and specific type of airway abnormality 9. While a more simplistic binary approach may be reasonable for screening, the gold standard for airway assessment-management paradigm should be based on a comprehensive anatomical approach.