Author's reply to Thomas et al.

Editor—We are pleased that Thomas and colleagues¹ agree with many of the conclusions in our Editorial and audit^2,3 of suboptimal laryngeal mask airway (LMA) placement. We agree with several points they make in their letter. If initial attempts fail, Magill forceps can be used to guide the flexible LMA beyond the epiglottis, or the cuff can be deflated even further, or more jaw thrust can be applied. All of these are included in our proposals. It is self-evident that there should be adequate levels of anaesthesia, but it would have been unnecessary to repeat such a fundamental point, as that necessity has been emphasized elsewhere.⁴

We suspect it is the expertise of Thomas and colleagues¹ that yields the excellent results they allude to; in contrast, our articles were written primarily for the benefit of non-experts, designed to improve their success rates. We doubt that Thomas and colleagues¹ will frequently have need to follow our suggested algorithm, given that their initial success rates are already so high.

However, there are points in their letter with which we find it difficult to agree, or that clearly need further research. The authors argue that in patients with a short laryngeal inlet it may be preferable to have part of the epiglottis within the bowl of the LMA, but do not provide evidence in support of this assertion. In our algorithm, we acknowledged that if the epiglottis sits in the bowl of the supraglottic airway device (SAD) without down-folding it may be judged acceptable to proceed. Problems arise when there is down-folding of the epiglottis in the bowl. Therefore, we think that to suggest having part of the epiglottis ‘preferably’ in the bowl is going too far, because then there is no way to control the position of the epiglottis and it could down-fold.

Thomas and colleagues¹ also question the advice to downsize to a smaller LMA to align its posterior rim with the proximal LMA cuff. They argue that it might lead to deterioration in the overall LMA seal, but without a view it is impossible to know whether the pharyngeal inlet is small or large. In our experience, all instances where we (A.A.J.V.Z.) had to change to a smaller size resulted in a more optimal seal, higher oropharyngeal leak pressures, and better functioning of the device.

Perhaps most fundamentally, Thomas and colleagues¹ believe that even videolaryngoscopy exerts such laryngoscopic force as to displace the SAD. This we think is the key difference between our approaches. It is, of course, possible to misuse a videolaryngoscope and to apply very large pressures with it to distort the anatomy. However, when used as intended, it is possible to obtain excellent views such as to detect and correct any malposition or any inconsistency of size or cuff inflation. The emphasis of our article was to move away from blind insertion and acceptance of position based only on apparent function. Indeed, we note that in 1983, Brain⁵ used direct laryngoscopy (thus risking the ‘excessive force’) to ascertain the causes of leaks and obstructions in the LMA then in development. It is Brain’s own approach that we have updated and adopted into our algorithm.

Thus, although we are slightly surprised that Thomas and colleagues¹ now eschew diagnosing problems with SAD placement through (in part) direct (video)laryngoscopy, we do agree that appropriate training is key to any success in airway management.

Declaration of interest

None declared.

References