Validation of manufacturers’ laryngeal mask airway size selection standard: a large retrospective study

BACKGROUND: Laryngeal mask airway (LMA) is a prominent supraglottic airway device, widely used especially in difficult airway management. However, the LMA sizes recommended by the manufacturers are not always well matched in clinical practice, which leads to complications. To date, there are rare models to validate whether the manufacturers’ standard is suitable for use in clinical practice. METHODS: A total of 58,956 patients undergoing general anesthesia using LMA device were included in the study between January 1, 2011 and December 31, 2018, to validate the adherence rate of LMA sizes according to the manufacturers’ recommendations. A logistic regression analysis was performed based on the actual LMA size used in clinical practice to establish separately size selection guidelines with gender, weight, and age as variables in adults, adolescents, and children. RESULTS: LMA insertions were analyzed in 50,776 (86.1%) adults, 3,548 (6%) adolescents, and 4,632 (7.9%) children. Suitability of manufacturers’ recommendations was higher in children [male: 86.02%; female: 85.09%] than adults [male: 72.75%; female: 78.13%] or adolescents [male: 73.4%; female: 70.79%]. For adults and adolescents, LMA size was better predicted using the regression model rather than the manufacturers’ recommendations [male adults: 82.4% (81.16–83.57%) vs. 73.21% (71.79–74.59%), P<0.05; female adults: 87.82% (86.65–88.9%) vs. 77.07% (75.6–78.48%), P<0.05; male adolescents: 79.45% (74.86–83.4%) vs. 72.05% (67.09–76.53%), P<0.05; female adolescents: 78.4% (71.11–84.31%) vs. 72.22% (64.54–78.82%), P<0.05]. For children, there was equal performance suitability using the regression model and the manufacturers’ recommendations. CONCLUSIONS: The model-based guidelines may provide more accurate directions for LMA size selection for adolescents and adults than the manufacturers’ weight-based recommendations, whereas the manufacturers’ recommendation in children is consistent with clinical practice.