This study aimed to assess the technique of using transesophageal echocardiography (TEE) to detect gastric inflation and to determine the optimal level of inspiratory pressure during face mask ventilation (FMV). In this prospective and randomized trial, seventy-five adults scheduled for cardiac surgery were enrolled to one of the three groups (P12, P15, P20) defined by the applied inspiratory pressure during FMV. After induction, mask ventilation was performed with the corresponding level of pressure-control ventilation for 2 min in each patient. Respiratory and hemodynamic parameters were recorded every 15 s. Arterial blood gases were tested before induction and at the time of intubation. Gastric cross-section area was detected using transesophageal echocardiography after intubation. The gastric cross-section areas were 3.1 ± 0.81, 3.8 ± 1.37 and 4.8 ± 2.29 cm2 respectively. It statistically increased in group P20 compared with group P12 and P15. PaCO2 before intubation statistically increased compared with the baseline in groups P12 and P15, while decreased in group P20. The mean values of PaCO2 equaled to 44.4 mmHg (40-51.5), 42.9 mmHg (34-50.5) and 36.9 mmHg (30.9-46) respectively in three groups. Peak airway pressure of 12-20 cmH2O could provide acceptable sufficient ventilation during mask ventilation, but 20 cmH2O result in higher incidence of gastric inflation. TEE is useful to detect the gastric inflation related to the entry of air into the stomach during pressure-controlled face mask ventilation.Trial Registration Number ChiCTR-IOR-14005325.
Keywords: Gastric inflation; Mask ventilation; Transesophageal echocardiography.