Increased gastric PCO2 during exercise is indicative of gastric ischaemia: a tonometric study.

Abstract

Diagnosis of gastric ischaemia is difficult and angiography is an invasive procedure. Angiographic findings may not correlate with clinical importance. To investigate whether tonometric measurement of intragastric PCO2 during exercise can be used to detect clinically important gastric ischaemia. 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 revascularisation procedure. Gastric PCO2 was measured from a nasogastric tonometer, with 10 minute dwell times, and after acid suppression. Gastric and capillary PCO2 were measured before, during, and after submaximal exercise of 10 minutes duration. 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 (PiCO2) 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 PCO2 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 PCO2 gradient correlated with clinical and gastroscopic severity; in patients reexamined after revascularisation (n=3), exercise tonometry returned to normal. Gastric tonometry during exercise is a promising non-invasive tool for diagnosing and grading gastrointestinal ischaemia and evaluating the results of revascularisation surgery for symptomatic gastric ischaemia.