The mechanism of Nissen fundoplication.

Six patients with objectively proven reflux oesophagitis were studied in association with fundoplication. Intraoperative manometry was performed with a conventional station-pull-through technique, using a constantly perfused catheter (1 ml/min) with four side holes. The drugs used for general anaesthesia did not influence the lower oesophageal sphincter. The lower oesophageal pressure was measured before and after fundoplication, after filling the stomach with 200 ml of air, and after gastric compression. The rise in lower oesophageal pressure after fundoplication varied widely, from 1 to 25 (mean 10) mmHg. After the gastric compression, the oesophageal pressure rise (mean 7, range 3-11 mmHg) corresponded to the increase in intragastric pressure (mean 6, range 4-8 mmHg). The results of the study suggested that the tightening effect of fundoplication on the distal oesophagus may not explain the antireflux mechanism of the operation. Instead the fundoplication seems to function as a flutter-valve.