Evaluation of adequacy of ventilation and gastric insufflation at three levels of inspiratory pressure for facemask ventilation during induction of anaesthesia: A randomised controlled trial

Abstract

Background: In this study, we aimed to compare three inspiratory pressures during facemask ventilation in paralysed patients regarding the subsequent incidence of gastric insufflation and the adequacy of lung ventilation.

Methods: In this randomised controlled trial, we included adult patients undergoing elective surgery under general anaesthesia. The patients were randomly allocated to receive positive inspiratory pressure (PIP) of 10, 15, or 20 cmH₂O during pressure-controlled mask ventilation. Antral cross-sectional area (CSA) was assessed by ultrasound at baseline before mask ventilation and after endotracheal intubation and gastric insufflation was defined as increased CSA after endotracheal intubation > 30% of the baseline measurement. The primary outcome was the incidence of gastric insufflation. Other outcomes included the tidal volume, and the incidence of adequate ventilation (tidal volume of 6-10 mL/kg predicted body weight).

Results: We analysed data from 36 patients in each group. The number of patients with gastric insufflation was the lowest in the PIP 10 group (0/36 [0%]) in comparison with PIP 15 (2/36 [19%] and PIP 20 36/36 [100%] groups (P-values of 0.019 and < 0.001, respectively). The probability of adequate ventilation at any time point was the highest in PIP 10, followed by PIP 15, and was the lowest in the PIP 20 group.

Conclusion: An inspiratory pressure of 10 cmH₂O in paralysed patients provided the least risk of gastric insufflation with adequate ventilation during induction of general anaesthesia compared to inspiratory pressure of 15- and 20 cmH₂O.

Keywords: Facemask ventilation; Gastric insufflation; Paralysed patients; Ultrasonography.