title: Increased gastric-end tidal P(CO2) gap during exercise at high altitude measured by gastric tonometry.
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.
authors: Centre for Altitude Space and Extreme Environment Medicine, UCL Institute for Human Health and Performance, Archway Campus, Highgate Hill, London, United Kingdom. dan.s.martin@gmail.com
authors: Daniel
authors: D
authors: Martin
authors: Stuart
authors: S
authors: McCorkell
authors: Andre
authors: A
authors: Vercueil
authors: Paul
authors: P
authors: Gunning
authors: Mark
authors: M
authors: Cox
authors: John
authors: J
authors: Dick
authors: Monty
authors: M
authors: Mythen
authors: Mike
authors: M
authors: Grocott
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005753:Gastric Mucosa / Q000098:blood supply* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods*; D008991:Monitoring, Physiologic / Q000379:methods; D010101:Oxygen Consumption; D012016:Reference Values; D012044:Regression Analysis; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide