Gastro-oesophageal acid reflux and sphincter pressure in normal human subjects.

Twelve-hour continuous recording of pH at the distal end of the oesophagus and manometric study of the basal gastro-oesophageal sphincter pressure were carried out in 26 normal human subjects. Eighteen of the 26 had 1-33 reflux episodes. The duration of each episode was shorter than 15 min in 16 of these 18 subjects. One single reflux episode lasting 15-30 min occurred in two, and one lasting 30-45 min was recorded in one. The total duration of low pH is expressed in percentages of the total time of recording and is dependent on the criteria used for low pH. On automatic analysis of the course of investigation, pH below 2.3 was found in five, pH below 3 in 17, and pH below 4 and 5, in 18 of the 26 subjects. Basal gastro-oesophageal sphincter pressure flutuated between 8 and 24 mmHg. The results of the study would suggest that in healthy, asymptomatic individuals the gastro-oesophageal barrier against reflux may be periodically incompetent. If contact between acid gastric contents and the oesophageal mucosa is a factor provoking the symptom heartburn, low oesophageal pH need not necessarily give rise to symptoms, i.e. the sensibility to low pH is either individual, or patients with symptoms have considerably more frequent and longer lasting episodes of reflux with low oesophageal pH than have normal subjects.