Lower oesophageal sphincter resting pressures in achalasia and the response of the sphincter to swallowing and drugs.

Previous reports on the profile of lower oesophageal sphincter (LOS) pressures and swallow responses in achalasia have been conflicting. Both normal and high resting pressures have been reported. Many reports have noted a failure of relaxation of the LOS in response to swallowing. Manometric studies were performed on 17 untreated patients with achalasia, of whom 76% were found to have a resting peak end-inspiratory pressure significantly greater than normal (P = 0,001). Nine patients showed relaxation of the LOS in response to swallowing but this relaxation was usually inadequate and of brief duration. Contractions were premature in 16 patients. One patient showed a manometric pattern closely simulating a Mobitz type 1 atrioventricular block in response to repeated swallows. A common pathophysiological process is postulated. In one patient an injection of secretin reduced the high resting LOS pressure. This supports previous evidence that a hypersensitive sphincter in achalasia is due to a hypersensitivity to gastrin. Hyoscine-N-butylbromide (Buscopan) caused a significant reduction in LOS pressure in all patients in whom it was used.