Increased gastric P-CO2 during exercise is indicative of gastric ischaemia: a tonometric study

Background-Diagnosis of gastric ischaemia is difficult and angiography is a n invasive procedure. Angiographic findings may not correlate with clinical importance. Aims-To investigate whether tonometric measurement of intragastric PCO2, du ring exercise can be used to detect clinically important gastric ischaemia. Methods-Fourteen patients with unexplained abdominal pain or weight loss we re studied. Splanchnic angiography served as the gold standard. Three patie nts were studied again after a revascularisation procedure. Gastric PCO2 wa s measured from a nasogastric tonometer, with 10 minute dwell times, and af ter acid suppression. Gastric and capillary PCO2 were measured before, duri ng, and after submaximal exercise of 10 minutes duration. Results-Seven patients had normal angiograms; seven had more than 50% steno sis in the coeliac (n = 7) or superior mesenteric artery (n = 4). Normal su bjects showed no changes in tonometry. In patients with stenoses, the media n intragastric PCO2 (PiCO(2)) 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 bloo d PCO2 gradient increased from 0.0 kPa (range -0.8 to 5.9) to 1.7 kPa (rang e 0.9 to 10.3; p<0.01). Only two subjects had abnormal tonometry at rest; a ll had supernormal values at peak exercise. The PCO2 gradient correlated wi th clinical and gastroscopic severity; in patients reexamined after revascu larisation (n = 3), exercise tonometry returned to normal. Conclusion-Gastric tonometry during exercise is a promising non-invasive to ol for diagnosing and grading gastrointestinal ischaemia and evaluating the results of revascularisation surgery for symptomatic gastric ischaemia.