Difficult intubation in obstetric general anaesthesia

Djabatey and Barclay’s audit, which looked for difficult and failed intubations in obstetric anaesthesia, is particularly important because, as they point out, ‘the impact of maternal death due to failed intubation is enormous’ [1]. We would like to contribute a number of points for discussion. Our first point is regarding their statement: ‘the trend away from obstetric general anaesthesia has been accompanied by a rise in the rate of failed intubation from 1:300 to 1:250’. These figures were taken from the paper by Hawthorne et al. [2] looking at the period 1984–1994 where this small apparent increase of about one case per year was not supported by statistical analysis. Moreover, the other paper referenced to support this claim in fact found no significant difference in the incidence of failed intubation over their 6-year study period [3]. A more recent audit by Saravanakumar and Cooper [4], looking at 1988–2004, showed an increase in failed intubation rate that again did not reach statistical significance. If a trend does exist, there are other factors to consider in addition to lack of practice. With an increasing rate of neuraxial block for caesarean section there exists the potential for general anaesthesia to be increasingly reserved for patients with co-morbidities, a group that may be predisposed to a higher incidence of airway abnormalities [5]. Our second point is regarding the criteria for determining which patients are classified as difficult intubations and, more particularly, as ‘failed intubations’. Without this information it is impossible to compare Djabatey and Barclay’s audit with others. Failed intubation can refer to the inability to intubate despite every effort or, as is often the case in failed intubation protocols, when it is not possible to intubate following a single dose of suxamethonium [2, 6] or after a restricted number of attempts [7]. It is easy to see how earlier recognition of ‘failure’ will lead to an apparent increase in failed intubation rates. This prompts the question, what proportion of the audit’s ‘difficult intubations’ would become ‘failed intubations’ if a protocol was followed that restricted intubation attempts? The authors specifically attribute their apparently low incidence of airway complications to, amongst other reasons, the above average rate of general anaesthesia in their hospital. We would argue that the best way to avoid a failed intubation is to avoid the need to intubate in the first place. Furthermore, the training of junior anaesthetists and obstetric ODPs in the management of rapid sequence induction can, with a degree of organisation, be achieved in general emergency theatres together with the appropriate use of simulation.