The 2015 Difficult Airway Society guidelines: what about the anticipated difficult airway? A reply

Dr Heidegger makes a very good point that the recent Difficult Airway Society (DAS) guidelines make no reference to the problem of anticipated difficult tracheal intubation, but only to the management of unanticipated difficulty 1. We are not in a position to comment on the terms of reference of the DAS Working Party since we were not members of it, but we might surmise that the primary purpose of these guidelines was to provide assistance to anaesthetists who found themselves facing unexpected difficulty after having committed themselves to the act of tracheal intubation. It is conceivable, for example, that in a case of anticipated difficult intubation, one course of management might be to avoid general anaesthesia altogether. So any guidelines would have to be very different than the ones in existence. The guidelines are also incomplete for at least one other reason, namely that they relate only to unanticipated circumstances where tracheal intubation was the intended primary plan (a happily rare, situation). In the probably more common circumstance where a supraglottic airway device (SAD) is the initial method chosen and has failed, there is in fact no consensus pathway. Should the anaesthetist choose to proceed to tracheal intubation or to rescue facemask ventilation? Or, should another attempt be made with another type of SAD? The answers to these questions may seem superficially straightforward but, in fact, require separate algorithms to assist team performance during a stressful situation. More pertinently, any guidelines of how to manage anticipated difficult intubation must necessarily involve discussion of the extent to which it is possible to predict when intubation (or mask ventilation or of SAD insertion) might be difficult. Yentis has provided an elegant analysis 2, but we have previously suggested that his conclusions were in part misinterpreted as suggesting it is not possible to predict difficulty accurately 3, 4. Heidegger's letter indicates that fuller discussion of these points is now warranted, whether through academic discussion or via consensus guidelines.