Optimal inspiratory pressure for face mask ventilation in paralyzed and unparalyzed children to prevent gastric insufflation: a prospective, randomized, non-blinded study.

BACKGROUND: Gastric insufflation is common during face mask ventilation and results in unfavourable respiratory events in children. The purpose of this study was to evaluate the effect of a muscle relaxant on gastric insufflation and determine the optimal inspiratory pressure during face mask ventilation in children. METHODS: Children aged one month to five years were randomly assigned to neuromuscular blocker (NM) or non-neuromuscular blocker (non-NM) groups. After administering intravenous anesthetics, face mask ventilation commenced via pressure-controlled mechanical ventilator. Initial inspiratory pressure was 10 cmH2O and was increased by 2 cmH2O until gastric insufflation was detected via gastric ultrasonography or epigastric auscultation. The primary outcome was the difference in the inspiratory pressure that causes gastric insufflation between the two groups. Diagnostic methods that detect gastric insufflation first were also evaluated. RESULTS: There was no significant difference in the median [interquartile range] inspiratory pressure inducing gastric insufflation between the non-NM (n = 52) and NM groups (n = 60) (18 [16-18] cmH2O vs 18.0 [16-20] cmH2O; median difference, 0 cmH2O; 95% confidence interval [CI], 0 to 2; P = 0.57). The incidence of gastric insufflation increased with increasing inspiratory pressure. Gastric insufflation was detected first by ultrasonography in 44% and by epigastric auscultation in 19% of the non-NM group (difference in percentage, 25%; 95% CI, 6 to 42; P = 0.006) and by ultrasonography in 73% and by epigastric auscultation in 7% of the NM group (difference in percentage, 66%; 95% CI, 50 to 78; P < 0.001). CONCLUSIONS: A neuromuscular blocking agent has minimal effect on the inspiratory pressure that causes gastric insufflation during face mask ventilation in children. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02471521); registered 15 June 2015.