Airway management lessons from case reports of negative outcomes. Comment on Br J Anaesth; 125: e168–70

Always noteand record the unusual … Publish it. Place it on permanent record as a short, concise note. Such communications are always of value (Sir William Osler).¹

Editor—A forthcoming issue of the British Journal of Anaesthesia (BJA) contains a report of two cases of tracheal trauma after difficult airway management in morbidly obese patients with coronavirus disease 2019 (COVID-19).² The authors should be commended for submitting these negative outcomes to the BJA, and the BJA must be congratulated for publishing them. High-ranking journals rarely accept such reports nowadays, and even though these reports often have major limitations, such as possible over-interpretation, lack of generalisability, or retrospective design,³ we can still learn a lot from them.⁴

Here are six lessons from that report:

• (i) Airway management is (still) not as safe as we might believe. It is rare that medical professionals report their own adverse events for at least two reasons: fear of reputational consequences and fear of legal consequences. Thus, there is likely a strong publication bias favouring case reports with positive results. Regarding safety of airway management, results are likely too optimistic as well.⁴ A good example is the interpretation of the results from The Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society (NAP4), the largest prospective study of major airway events occurring during anaesthesia, in the ICU and emergency department.⁵ The authors themselves state that only roughly 25% of the cases with adverse events were captured, indicating a more accurate incidence of perhaps 1:5500 or even greater instead of the published incidence of 1:22 000 for major airway events.⁶ Identifying the true incidence of adverse airway events is theoretically simple: we need further large prospective data including all cases, both elective and emergency, and cases with good and adverse outcomes, including death.⁷
• (ii) Obesity itself is a predictor of difficult airway management. This was shown by the results of NAP4, in which obese patients were twice as common in the population that suffered incidents than in the group that did not,⁵ and this was confirmed in a recent study from Australia.⁸ Anatomical alterations, such as the combination of a large tongue and excessive upper airway soft tissue, and physiological alterations, such as decreased functional residual capacity and increased oxygen consumption, are important disadvantages for obese patients.⁹ Whether obesity is a predictor of difficult mask ventilation is still debated.¹⁰ Regarding tracheal intubation, an analysis of electronic records of more than 67 000 patients showed that a BMI of >30 kg m⁻² was significantly associated with increased likelihood of more than one tracheal intubation attempt, but the odds of difficult intubation remained unchanged once BMI exceeded 30 kg m⁻².¹¹
• (iii) Laryngoscopy is not the same as intubation. It is important to distinguish between these two procedures, as difficult laryngoscopy can be followed by easy tracheal intubation. (This is common during conventional tracheal intubation.) Likewise, easy laryngoscopy can be followed by difficult tracheal intubation (‘you see that you fail’), which is the most common cause of failed tracheal intubation with videolaryngoscopy.¹² Even though the use of videolaryngoscopy improves the glottic view, there is currently no evidence that it reduces the number of tracheal intubation attempts or the incidence of respiratory complications.¹³ Whether videolaryngoscopy would have prevented the adverse event in the cases described² remains unclear.
• (iv) Tracheal tube introducers (‘bougies’) and rigid stylets are potentially dangerous. The cases reported show the potential dangers of rigid tools, such as tracheal tube introducers or rigid stylets, to facilitate tracheal intubation in patients with COVID-19, particularly in the absence of glottis visibility.^{14 , 15}
• (v) Fibreoptic intubation is an established alternative in patients with morbid obesity. Even though fibreoptic intubation is infrequently used as a first-choice technique for management of patients with morbid obesity, it is a tried-and-tested alternative for such situations¹⁶ and should always be considered.
• (vi) Airway management in obese patients with COVID-19: combining protection and best practice is essential. Various national airway societies have published consensus guidelines addressing airway management during the COVID pandemic.17, 18, 19 Besides a few techniques that should be strictly avoided, such as high-flow nasal oxygen and small-bore cannula cricothyroidotomy with jet ventilation, management of the difficult airway always involves weighing the risks for the patient and other persons involved, with the likelihood of first-attempt success. The technique chosen may ultimately differ according to local practices, resources, and experience.

In conclusion, publishing airway management case reports, above all those with negative outcomes, remains important. We need to expose more than the tip of the iceberg so that we can improve our daily practice in airway management to improve patient safety.

Declarations of interest

The author declares that they have no conflicts of interest.