Gastric tonometry in healthy volunteers

作者：Stephen O. Heard, Cathleen M. Helsmoortel, Joel Christopher Kent, ALBERT SHAHNARIAN, Mitchell P. Fink · 发表于：Critical Care Medicine · 年份：1991 · DOI：10.1097/00003246-199102000-00025 · 被引用次数：188 · 研究领域：Gastroesophageal reflux and treatments、Gastrointestinal motility and disorders、Helicobacter pylori-related gastroenterology studies

OBJECTIVE: To determine if intraluminal production of CO2 leads to underestimation of gastric intramural pH (pHi) by tonometry. DESIGN: Nonrandomized controlled study. PATIENTS: Healthy volunteers. INTERVENTIONS: NG tonometers were placed in healthy volunteers. Some of the volunteers (n = 11) were pretreated with ranitidine to prevent secretion of protons into the gastric lumen. Others (n = 13) were untreated (i.e., gastric acid secretion was uninhibited). MEASUREMENTS AND MAIN RESULTS: Gastric pHi was calculated from the arterial (HCO3-) and the tonometrically determined intraluminal PCO2 using the Henderson-Hasselbalch equation. Intraluminal PCO2 was significantly higher in the control group (54 +/- 14 torr [7.2 +/- 1.9 kPa]) than in the ranitidine-treated group (42 +/- 4 torr [5.6 +/- 0.4 kPa], p = .02). Mean gastric luminal pH was 1.9 +/- 0.6 in the control group as compared with 6.7 +/- 0.7 in volunteers treated with ranitidine (p less than .01). Mean calculated gastric pHi was 7.30 +/- 0.11 in the untreated group and 7.39 +/- 0.03 in the ranitidine-treated group (p less than .03). CONCLUSIONS: These data suggest that intraluminal production of CO2 from the titration of gastric HCO3- by secreted H+ can result in the underestimation of gastric pHi by tonometry. This phenomenon can be eliminated by H2-receptor blockade.