Volume and pH of gastric contents in patients undergoing gynecologic laparoscopic surgery during emergence from general anesthesia: A prospective observational study

Abstract

Objective: To find out the volumes and pH values of the digestive contents during emergence in patients undergoing elective gynecologic laparoscopic surgery under general anesthesia. Materials and Methods: One hundred patients scheduled for surgery under general balanced anesthesia with standard monitoring were allocated in the present study. Gastric volumes greater than 0.4 mL/kg and pH of less than 2.5 were set as cut-off points to establish the risk of aspirated pneumonitis. Prior to insufflation of CO2 gas into the participants' abdominal cavity and placing them in lithotomy or Trendelenburg position, anesthetists inserted an orogastric tube to deflate the patients' stomach. Then gastric volumes and pH values were measured at hourly intervals through the operation. Results: Eighty-nine participants completed the study. The pH and gastric volumes of high-risk and non-high-risk groups showed statistically significant differences (p<0.001), as 1.1±0.4 and 1.1±0.8 mL/kg, and 2.8±2.2 and 0.3±0.4 mL/kg, respectively. Though their ages (p=0.047), body mass index (BMI) (p=0.015), and pre-medication drugs (p<0.001) showed significant differences, they were not apparent in the pre-fluid loading, fasting, and surgical time. Conclusion: During emergence from general anesthesia, 65.2% of the patients undergoing gynecologic laparoscopic surgery were exposed to a high risk of aspirated pneumonitis. The present study showed significant association with age, BMI, and pre-medication drugs. Investigators suggested that patients with a BMI greater than 25 kg/m2 administering H2 receptor antagonist or a proton pump inhibitor as premedication, and having gastric content drainage prior to endotracheal tube extubation should have a low risk of pulmonary aspiration.