Optimal Inspiratory Pressure for Facemask Pressure-controlled Ventilation in Children

The purpose of this study is to find an optimal inspiratory pressure to provide adequate tidal volume and prevent gastric insufflation in pediatric patients. The children under 5 years old are randomly assigned to muscle relaxation group and non-relaxation group. For muscle relaxation group, routine anesthesia induction is performed with muscle relaxant and mask ventilation is started by pressure-controlled mechanical ventilation. Gastric auscultation and abdominal ultrasonography are performed simultaneously during mask ventilation to detect inflow of air. Initial inspiratory airway pressure is 10 cmH2O and increased gradually by 2 cmH2O until gastric insufflation is detected by either of two methods. Tracheal intubation is done after detection of gas. For non-relaxation group, mask ventilation is performed in a same manner, without muscle relaxant. After detection of gas by any of the two methods, rocuronium 0.6 mg/kg is administered and tracheal intubation is performed.