24-hr measurement of gastric mucosal perfusion in conscious humans

Gastric mucosal blood flow estimation in humans is obtained through an endoscope and the time of measurement lasts only a few minutes. Thinking that long-term monitoring of mucosal perfusion would be a significant contribution to the study of gastric physiology, we registered gastric mucosal blood flow continuously for 24 hours, using single fiber laser-Doppler technology.

The study was undertaken in 16 healthy subjects (8 of them had their gastric acidity inhibited with a proton pump inhibitor) and in 8 patients with an endoscopically proven, active duodenal ulcer. A 140 cm-long single fiber laser-Doppler microprobe was positioned through a gastrointestinal tube in the middle of the gastric corpus and the mucosal microcirculation was monitored from 14.00 h until 13.59 h the following day. Data were stored and processed to evaluate the probable circadian rhythms, using maximum entropy spectrum analysis.

We found that the daily variations of gastric mucosal perfusion follow a circadian rhythm. The respective patterns with maximum and minimum values were: healthy controls, maximum at 02.00, 10.00, 18.00 h and minimum at 5.30, 14.00 and 22.00 h. Healthy controls treated by a proton pump inhibitor, maximum at 02.00, 07.00, 18.00 h and minimum at 04.00, 12.00 and 22.00 h. Ulcer patients, maximum 07.00 and 21.00 h and minimum at 17.00 and 24.00 h.

It is concluded that long-term measurement of gastric mucosal blood flow in conscious humans is feasible and that this factor of gastric physiology follows a concrete circadian rhythm, which is not particularly influenced by acid inhibition, but is completely distorted in ulcer patients.