Detection of gastric inflation using transesophageal echocardiography after different level of pressure-controlled mask ventilation: a prospective randomized trial

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.