Body positions and esophageal sphincter pressures in obese patients during anesthesia

Background The lower esophageal sphincter (LES) and the upper esophageal sphincter (UES) play a central role in preventing regurgitation and aspiration. The aim of the present study was to evaluate the UES, LES and barrier pressures (BP) in obese patients before and during anesthesia in different body positions. Methods Using high-resolution solid-state manometry, we studied 17 patients (27-63 years) with a BMI >= 35 kg/m2 who were undergoing a laparoscopic bariatric surgery before and after anesthesia induction. Before anesthesia, the subjects were placed in the supine position, in the reverse Trendelenburg position (+20 degrees) and in the Trendelenburg position (-20 degrees). Thereafter, anesthesia was induced with remifentanil and propofol and maintained with remifentanil and sevoflurane, and the recordings in the different positions were repeated. Results Before anesthesia, there were no differences in UES pressure in the different positions but compared with the other positions, it increased during the reverse Trendelenburg during anesthesia. LES pressure decreased in all body positions during anesthesia. The LES pressure increased during the Trendelenburg position before but not during anesthesia. The BP remained positive in all body positions both before and during anesthesia. Conclusion LES pressure increased during the Trendelenburg position before anesthesia. This effect was abolished during anesthesia. LES and BPs decreased during anesthesia but remained positive in all patients regardless of the body position.