UCL Discovery

Abstract

Using automated air gastric tonometry, the hypothesis that gastric perfusion. is reduced while exercising at high altitude was explored. This prospective observational study of 5 well acclimatized healthy volunteers was performed during a medical research expedition to Chamlang base camp (5000 m), Hongu valley, Nepal. We used gastric tonometry at rest and during graded submaximal exercise. The end-tidal partial pressure of carbon dioxide was subtracted from the gastric mucosal partial pressure of carbon dioxide to calculate the P-CO2 gradient, which is a marker of gastric mucosal perfusion. When compared with rest, there was no increase in the mean P-CO2 gradient at the lower work rate (0.22 vs. 0.18, p = 0.10), but an increase was seen between rest and the higher work rate (0.22 vs. 0.77, p = 0.04). We conclude that exercising while at high altitude can lead to a raised P-CO2 gradient when gastric tonometry is performed, indicating reduced perfusion. This may represent reduced gastric mucosal perfusion under these conditions.