24-hr measurement of gastric mucosal perfusion in conscious humans.

BACKGROUND/AIMS: 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.

METHODOLOGY: 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.

RESULTS

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.

CONCLUSIONS

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.