Twenty-four-hour pH measurements in morbid obesity: effects of massive overweight, weight loss and gastric distension

Abstract

Objective: To investigate the influence of untreated (super)morbid obesity and the effects of massive weight loss and chronic gastric distension on gastro-oesophageal reflux.

Patients and methods: Seventeen young morbidly obese patients (32 years old; body weight 166.5 kg; body mass index 55 kg/m2) underwent 24-h ambulatory oesophageal pH monitoring before weight reduction and 4 months after treatment with energy-restricted diet, physical exercise and intragastric balloon or sham placement in a randomized, double-blind design. To minimize bias, both 24-h pH measurements were performed under similar conditions and dietary intake, and patients were matched for age, sex, body weight and body mass index.

Results: At the start, group median data for the fraction of total time, time upright and time supine with pH less than 4 were within normal limits. After a major median weight loss of 38.8 kg in 4 months these parameters did not change. On an individual basis, five out of 17 patients had pathological acid reflux prior to weight loss. This reversed to normal in three subjects, but remained abnormal in two and became abnormal in one patient. The weight loss (58.4 kg) of those remaining or becoming acid refluxers was significantly different (P < 0.01) from those with normal or normalizing pH measurements (36.9 kg). A 4-month period of gastric distension by a 500 ml balloon did not influence acid reflux parameters.

Conclusion: The influence of untreated (super)morbid obesity on acid reflux was less pronounced than expected. There was also no major adverse effect of chronic gastric distension. Only excessive weight loss (i.e. 58 kg) appeared to have an untoward effect on acid reflux.