Intubation training in the real world

I would like to comment on the recent Editorial written by Drs Cormack and Lehane [1], who, of course, are well known worldwide for their work in the mid 1980s, when they described a classification of laryngeal view, with the aim of assisting in training the skill of intubation [2]. Cormack and Lehane start by voicing their concern over the escalating number of deaths related to general anaesthesia in recent Confidential Enquiries into Maternal and Child Health (CEMACH) reports. They quote figures of 0, 3 and 7 deaths for the last three triennia. The figures are less supportive of their argument when only those cases where airway management was the primary problem are counted, in which case the figures reduce to 0, 0, 3 (arguably 2). They are even less supportive when we consider the periods prior to 1996. In the 1970–90s, one might anticipate that problems with intubation would occur less frequently as the population was smaller, the reports excluded Scotland and Northern Ireland until 1984 and Caesarean section was about a quarter as frequent as it now. Despite this there were approximately 98 anaesthesia related deaths in the three triennia of the 1970s, 43 in the 1980s and 14 in the 1990s. Anaesthetic deaths directly attributable to airway problems in the six triennia prior to 1994 were 16 (1976–78), 8 (1979–81), 10 (1982–84), 6 (1984–87), 1 (1988–90) and 4 (1991–94). Many of the reports note deaths despite care delivered by experienced anaesthetists and also report failure to recognise oesophageal intubation. While one should be cautious with interpretation of small numbers, it is interesting to note that these figures show a marked reduction in airway related deaths coinciding with the introduction of the laryngeal mask airway in 1988. In reality, other factors such as the routine availability of capnography and senior involvement in such cases are perhaps more influential. It is pleasing that progress has been made although of course, there is no room for complacency. However if this is the basis of the authors’ argument for an increasing problem, it is not particularly persuasive. There are many good aspects of Cormack and Lehane’s approach to training tracheal intubation. They emphasise the importance of the gum elastic bougie (GEB) and there is considerable literature to show not only that it is device of considerable utility [3-5] but also that it is widely used [6]. Most anaesthetists would agree that it should be instantly available to every trainee when learning the fundamental anaesthetic skill of intubation, and thereafter. Personally I would go further than Cormack and Lehane and comment that the quality of the GEB is paramount, insisting that the only one used in our hospital (until a replacement is proven to be of similar efficacy and safety) is the original gum elastic bougie [7, 8]. The authors argue that grade 3 laryngoscopy is rather infrequent and that infrequent exposure will lead to inadequate training of anaesthetists. This argument is undermined somewhat because of apparently inaccurate estimations of its frequency. They perform statistical analysis based on an assumed incidence of ‘grade 3 laryngoscopy’ of approximately 1.2% (1 in 83). This leads to certain conclusions. In their 1984 paper [2] they performed a similar analysis, although on that occasion they assumed an incidence of grade 3 intubation of 0.05% (1 in 2000). Their conclusions and argument rely on these figures, which are both likely to be wrong. The range of incidences reported in unselected series is from 0.3% [9] (in a paper co-authored by Dr Cormack) to 10% [10]. In selected patients grade 3 intubation may occur with an incidence of 13–20% [11, 12]. The most robust figure comes from Shiga’s meta-analysis of ‘apparently normal patients’ [13]. In this study the incidence of grade 3 intubation in 50 760 patients was 5.8% (1 in 17) which is in keeping with Latto’s data that the GEB is used in 4% of intubations [6]. This suggests grade 3 intubation is between five and 100 times more frequent than Cormack and Lehane estimate, leading to different conclusions that those they arrive at. Cormack and Lehane suggest that anaesthetists lacking the training which they advocate are likely to fail when encountering grade 3 intubations and that death may ensue. Their argument then follows that effective use of the GEB will almost eliminate failed intubation. Success rates with the gum elastic bougie vary from around 90% to 99% [5, 6]. In the three most recent United Kingdom publications documenting failed intubation over considerable periods there was one case of aspiration and no other maternal harm associated with a total of 79 failed intubations [14-16]. Of note, in 25% of cases it appears the laryngeal view was grade 1 or 2. There is clear evidence that the GEB is a lifesaving device and it is obvious that trainees should rapidly become expert in its use but I do have difficulty with some of Cormack and Lehane’s suggestions as to how to achieve this training, first described 23 years ago and now re-iterated. Time and space do not allow these to be presented in detail and many are covered in a recent editorial [17] however I would like to reinforce two points. First, two aspects of Cormack and Lehane’s proposal are ethically contentious in modern practice. The first is the proposal to restrict use of the laryngeal mask by trainees. There are no scientific data to suggest this is beneficial for these patients. However unnecessary paralysis and intubation have inherent risks and are highly likely to expose these patients to avoidable additional risk. This cannot be acceptable without informed patient consent. Similarly it seems unreasonable to deliberately make intubation more difficult than necessary: intentionally converting a technique that is performed under direct vision into a partially blind technique. Again this change of practice offers the patient no benefit and exposes them to risk. It is one thing to perform safe laryngoscopy, avoiding excessive force and accepting that many of a trainee’s laryngoscopies will be grade 3a [5] and therefore using the bougie on a regular basis to hone this important skill. It is quite another thing to intentionally hinder a procedure, the performance of which is central to patient safety. It cannot be appropriate to use patients as manikins. Secondly, the editorial appears to promote a culture where ‘intubation is king’. While tracheal intubation is often the airway of choice and all anaesthetists should be expert at tracheal intubation, it does not follow that failed intubation is in itself ‘a failure’. It seems appropriate to regard anaesthetic care from the patient’s point of view, not the anaesthetist’s: the patient is likely to desire an anaesthetist who will manage their airway safely and be unlikely to care whether this involves intubation or not. There are valid alternatives to intubation, both for routine care and when intubation is chosen but fails. It is notable that Cormack and Lehane’s editorial, which variously describes intubation as ‘our most trustworthy technique’ and ‘as near a perfect airway as we are ever likely to get’ offers no alternatives to intubation as a means of managing the airway and makes no suggestions at all as to how to manage failed intubation when it does occur. Of note, recent advances in supraglottic airway technology are making these not only easy to use, but also increasing the level of protection against aspiration that they provide [18, 19]. The authors suggest that a combination of improved training in direct laryngoscopy and selective training of a cohort of experts in fibreoscopy can ‘eliminate failed intubation’ [1] and have suggested this previously (Cormack R. Training in intubation (abstract), Difficult Airway Society, 2004). This is an ‘anaesthetist-centred’ goal and it in itself seems illogical from their previous arguments. They state that direct laryngoscopy has a failure rate and infer that they agree with Mason [20] that fibreoptic intubation should only be used by an expert in emergencies. Given that difficult and failed intubation is many times more frequent during emergency than elective anaesthesia [14-16], and such anaesthesia is often provided by trainees working alone, it is difficult to see how their solution stands up. Ironically it is perhaps the belief in the primacy of intubation and the aim of ‘eliminating failed intubation’ that has the greatest potential to cause patient harm. The authors state, without supporting reference, that ‘experienced anaesthetists can testify to intubating over decades without trouble’, ‘trauma typically occurs from inadequately trained personnel attempting grade 3 intubation’ and ‘successful intubation would eliminate all airway disasters’. Such a goal supported by such strongly worded statements leads me to worry that failed intubation is then seen as a performance failure on the part of the anaesthetist, and perhaps by those judging him or her. This, in turn is likely to lead to pressure to persist with intubation attempts when this is not in the patient’s interest, resulting in risk or damage to the patient. The best available closed claims data, from America, makes it clear that when difficulty is encountered intubation attempts frequently persist for too long, leading to considerable patient harm [21]. No-one should believe that the United Kingdom is free from this: it is not [22], (personal communication: R. Symons, National Health Service Litigation Authority). It seems sounder to judge an anaesthetist, not on whether he or she fails to intubate, but on how he or she manages the consequences of such an occurrence [17]. A more patient-centred target might be to ‘minimise patient harm associated with difficult airway management’. Cormack and Lehane’s editorial sadly, does not progress us forward in this aim. A more progressive document remains the Difficult Airway Society guidelines for management of unanticipated difficult intubation [23]. The old adage is worth repeating: ‘patients do not die of failed intubation, but of failure to maintain oxygenation and ventilation’. I am an ordinary member of the Difficult Airway Society and when their guidelines were being developed I offered advice. I was not otherwise involved in their production.