Large Buffering Effect of the Duodenal Bulb in Duodenal Switch: a Wireless pH-Metric Study

Bariatric procedures result in massive weight loss, however, not without side effects. Gastric acid is known to cause marginal ulcers, situated in the small bowel just distal to the upper anastomosis. We have used the wireless BRAVO™ system to study the buffering effect of the duodenal bulb in duodenal switch (DS), a procedure in which the gastric sleeve produces a substantial amount of acid.

We placed a pre- and a postpyloric pH capsule in 15 DS-patients (seven men, 44 years, BMI 33) under endoscopic guidance and verified the correct location by fluoroscopy. Patients were asked to eat and drink at their leisure, and to register their meals for the next 24 h.

All capsules but one could be successfully placed, without complications. Total registration time was 17.2 (1.3-24) hours prepyloric and 23.1 (1.2-24) hours postpyloric, with a corresponding pH of 2.66 (1.74-5.81) and 5.79 (4.75-7.58), p < 0.01. The difference in pH between the two locations was reduced from 3.55 before meals to 1.82 during meals, p < 0.01. Percentage of time with pH < 4 was 70.0 (19.9-92.0) and 13.0 (0.0-34.6) pre and postpylorically, demonstrating a large buffering effect.

By this wireless pH-metric technique, we could demonstrate that the duodenal bulb had a large buffering effect, thus counteracting the large amount of gastric acid passing into the small bowel after duodenal switch. This physiologic effect could explain the low incidence of stomal ulcers.