Lower oesophageal sphincter tone increases after induction of anaesthesia in pigs with full stomach

Abstract

Purpose: The lower oesophageal sphincter (LOS) is the main mechanism that prevents gastro-oesophageal regurgitation during anaesthesia. The aim of this study was to assess the effect on lower oesophageal sphincter pressure (LOSP) of rapid sequence induction in pigs with full stomachs. Methods: Lower oesophageal sphincter pressure and oesophageal barrier pressure (BrP = LOSP minus gastric pressure) were measured using a water-perfused manometric catheter method in 12 pigs after gastric filling with 500 ml of liquid nutrient mixture. Six pigs were randomly allocated to receive 5 mg·kg-1 propofol and 3 mg·kg-1 succinylcholine iv, and six pigs received 8 mg·kg-1 thiopentone and 3 mg kg-1 succinylcholine iv. Results: After induction, mean LOSP increased during the period with fasciculations from 19 ± 4 mmHg to 28 ± 1 5 mmHg in the propofol-succinylcholine group and from 23 ± 6 mmHg to 36 ± 7 mmHg in the thiopentone-succinylcholine group. The LOSP remained elevated after the fasciculations. LOSP and BrP were not different between the groups. Conclusions: Induction of anaesthesia with propofol-succinylcholine or thiopentone-succinylcholine increases LOSP and, consequently, BrP in pigs with a full stomach. This increase begins before fasciculations and remains elevated for the period when intubation would occur.