Increased gastric p(CO2) during exercise is indicative of gastric ischaemia: A tonometric study

Abstract

Background - Diagnosis of gastric ischaemia is difficult and angiography is an invasive procedure. Angiographic findings may not correlate with clinical importance. Aims - To investigate whether tonometric measurement of intragastric P(CO2) during exercise can be used to detect clinically important gastric ischaemia. Methods - Fourteen patients with unexplained abdominal pain or weight loss were studied. Splanchnic angiography served as the gold standard. Three patients were studied again after a revascularization procedure. Gastric P(CO2), was measured from a nasogastric tonometer, with 10 minute dwell times, and after acid suppression. Gastric and capillary P(CO2) were measured before, during, and after submaximal exercise of 10 minutes duration. Results - Seven patients had normal angiograms; seven had more than 50% stenosis in the coeliac (n=7) or superior mesenteric artery (n=4). Normal subjects showed no changes in tonometry. In patients with stenoses, the median intragastric PCO2 (Pi(CO2)) at rest was 5.2 kPa (range 4.8-11.2) and rose to 6.4 kPa (range 5.7-15.7) at peak exercise; the median intragastric blood P(CO2) gradient increased from 0.0 kPa (range -0.8 to 5.9) to 1.7 kPa (range 0.9 to 10.3; p<0.01). Only two subjects had abnormal tonometry at rest; all had supernormal values at peak exercise. The P(CO2) gradient correlated with clinical and gastroscopic severity; in patients reexamined after revascularization (n=3), exercise tonometry returned to normal. Conclusion - Gastric tonometry during exercise is a promising non-invasive tool for diagnosing and grading gastrointestinal ischaemia and evaluating the results of revascularization surgery for symptomatic gastric ischaemia.