Gastro-oesophageal pressure gradient changes produced by induction of anaesthesia and suxamethonium.

The pressures in the lower oesophageal sphincter (high pressure zone or HPZ) and stomach were measured in 15 patients with duodenal ulcer and 14 patients with no gastrointestinal disease. All the patients were premedicated with morphine 10 mg i.m. In the patients without duodenal ulcer, the pressure gradient between HPZ and stomach was 6.6 +/- 0.62 mm Hg (mean +/- SEM) before diminishing to 4.9 +/- 0.86 after induction of anaesthesia with thiopentone. During fasciculations following i.v. suxamethonium, the gradient increased to 7.1 +/- 1.0 mm Hg. In patients with duodenal ulcer, although the absolute pressures were less, the gradients during the study were similar to those in healthy patients. We conclude that there is no increased risk of regurgitation during fasciculations induced by suxamethonium.