This small randomized clinical trial of manometry guided cuff inflation [Citation1] provides some useful data supporting safer use of the supraglottic airway device (SAD), the LMA SupremeTM, during laparoscopic cholecystectomy. The use of pneumoperitoneal distension provides potentially difficult conditions for lung ventilation and increased risk for possible aspiration of gastric contents. The author’s technique for cuff inflation, using manometry to measure and then adjusting the intracuff pressure to the Peak inspiratory pressure, and then increasing intracuff volume in small increments to allow leak free lung ventilation despite the increased impedance provided by pneumoperitoneum, allows adequate ventilation without pharyngeal damage being caused by the LMA. Passage of an intragastric tube sump suction device through the LMA SupremeTM to empty the stomach is an integral part of their technique. This maneuver should reduce the risk of regurgitation and aspiration of gastric contents. They showed significant reductions in pharyngolaryngeal morbidity in their experimental group when compared to a control group where intracuff pressure was set at 60 cm H2O pressure, the maximal pressure allowed by the manufacturer’s recommendation. They conclude that adequate sealing can be provided at lower cuff volumes and intracuff pressures than this level of 60. Their conclusions only apply to their defined population of relatively healthy, non-obese individuals with no airway difficulty, and cannot be extended to questions of safety or efficacy for LMA use in complex or high risk situations [Citation2].
Using manometry to monitor cuff pressure is not a new idea, but neither is it a common practice in many areas of the world. Pharyngolaryngeal morbidity caused by overdistension of these cuffs has provided rates for sore throat and dysphagia as high as 50%, with some instances of much more significant complications being engendered [Citation3]. Archie Brain, the original inventor of the LMA, and his co authors wrote of this in an editorial in 2014 [Citation3]. A survey which they had conducted found that “anaesthetists in the UK are not routinely checking … cuff pressures.” Many practitioners rely on their own clinical sense of the adequacy of cuff inflation and are not adequately following up with their patients to assess the morbidity they are causing. Brain and his colleagues propound and debunk five common myths, to which the study by Wang and colleagues [Citation1] adds. These are:
The Manufacturers recommended volumes for cuff inflation lead to the recommended intracuff pressures. For a variety of reasons this is untrue and therefore unsafe.
Sore throats and dysphagia after LMA use are infrequent and unrelated to cuff pressures. The current study shows that even when one carefully limits the intracuff pressure to the 60 cm H2O limit set by the manufacturer, pharyngolaryngeal morbidity is noted in approximately 33% of subjects. This prevalence can be lowered by using lower cuff volumes and pressures without sacrificing efficacy in the defined population.
Higher volumes and pressures may cause morbidity but it is minor, and at least you get a good seal. Untrue and dangerous as this is, it is not an uncommon misperception. The current study again shows that adequate seal is obtained in the defined population at considerably reduced volumes and pressures than the maximum recommended by the manufacturer.
Clinicians can judge a cuff pressure by using their fingertips on the pilot balloon. This was not tested in our current study but has been debunked elsewhere. One can use a manometer to see one’s own skill in this regard. And finally;
The worst that can happen is a sore throat and dysphagia for a limited time. Much other data from case reports refute this myth, and one cannot make any firm recommendations based on the current study, simply because no major complications were seen in this small series. One must continue to follow other studies and series [Citation2].
We are now some 37 years into our collective experience with the use of the LMA since its invention in 1983. The LMA SupremeTM was itself introduced to use in 2007 and has been subject to several comparisons with other SADevices [Citation4]. The current study, which tests the controlled use of the LMA SupremeTM for laparoscopic surgery in relatively healthy, non-obese patients, should provide support for continued expansion of the use for these devices in clinical practice.
Disclosure statement
No potential conflict of interest was reported by the author(s).
References
- Wang MH, Zhang DS, Zhou W, et al. Effects of peak inspiratory pressure-guided setting of intracuff pressure for laryngeal mask airway SupremeTM use during laparoscopic cholecystectomy: a randomized controlled trial. J Invest Surg. 2021;34(10):1137–1144. doi:https://doi.org/10.1080/08941939.2020.1761487.
- Cook TM. Strategies for prevention of airway complications: a narrative review. Anaesthesia. 2018;73(1):93–111. doi:https://doi.org/10.1111/anae.14123.
- Bick E, Bailes I, Patel A, Brain AIJ. Editorial: fewer sore throats and a better seal: why routine manometry for laryngeal mask airways must become the standard of care. Anaesthesia. 2014;69(12):1304–1306. doi:https://doi.org/10.1111/anae.12902.
- Wong DT, Yang JJ, Jagannathan N. Brief review: the LMA SupremeTM supraglottic airway. Can J Anesth/J Can Anesth. 2012;59(5):483–493. doi:https://doi.org/10.1007/s12630-012-9673-0.