Comparison of leak fraction between the laryngeal mask airway and endotracheal tube during anesthesia: a single-center retrospective study.

The use of the laryngeal mask airway (LMA), which offers the benefits of ease in insertion and prevention of tracheal damage, is associated with a risk of flow leakage. This study analyzed our extensive database to compare leakage associated with the use of LMA and endotracheal tube (ETT). Adult patients who underwent chest wall, abdominal wall, inguinal region, limb, transurethral, or transvaginal surgery and received either LMA or ETT between January 2007 and March 2020 were included. The leak fraction was calculated as (inspiratory tidal volume-expiratory tidal volume)/(inspiratory tidal volume) × 100% every minute during intraoperative stable positive pressure ventilation. The median leak fraction was calculated for each case. The leak fraction in the LMA group demonstrated a left-skewed distribution with a larger proportion of excessive leak fraction. The leak fraction in the LMA group (median, 7.9%; interquartile range, 4.8-11.4%) was significantly lower than that in the ETT group (median, 9.1%; interquartile range: 5.5-12.4%; P < 0.001). This tendency was consistent across subgroups divided by sex, age, type of surgery, and ventilation mode. We propose that LMA provides leakage comparable to or less than ETT in most cases if stable positive pressure ventilation is achieved.