Comparison of actual and ideal body weight for selection of appropriate size of ProSeal™ laryngeal mask airway in overweight and obese patients: A prospective, randomised study

Background and aims: The ProSeal™ laryngeal mask airway (PLMA) has advantages of providing better cuff seal and the presence of a gastric drain tube. The manufacturer recommends actual body weight (ABW) for size selection. Pharyngeal area reduces with increase in body mass index (BMI); hence, in overweight patients, PLMA selected on ABW may not fit well. We hypothesised that the ideal body weight (IBW) would be more appropriate in size selection of PLMA.

Methods: This randomised, single-blind study included 124 patients of 20-60 years and American Society of Anesthesiologists Class I-II, with BMI >25. Patients were randomly divided into two groups. In Group ABW, PLMA was selected based on ABW (62 patients) and in Group IBW, PLMA was selected based on IBW (62 patients). The primary outcome was the first-attempt insertion success rate. Oropharyngeal air leaks, gastric air leaks, drain tube air leaks, insertion difficulty scores and postoperative complications were assessed. Fibre-optic view (Grade I-IV) was assessed for proper placement by a blinded assessor. Statistical analyses were performed using Chi-square test or Fisher's exact test.

Results: First-attempt insertion success rate and overall insertion success rates were similar in both the groups. Group IBW patients had significantly less resistance during insertion, lower peak airway pressures, successful nasogastric tube insertions, better fibre-optic views and less post-operative complications. Oropharyngeal leak pressure and instrumentation used for insertion were comparable.

Conclusion: IBW is preferable for the size selection of the PLMA in overweight and obese patients compared to the ABW.