Experimental studies on the prediction and prevention of stress ulcers using tonometry, reflectance spectrophotometry and oxygenated perfluorochemicals.

The present study investigates whether oxygenated perfluorochemicals protect the gastric mucosa against hemorrhage-induced stress ulceration. The influence of oxygenated perfluorochemicals on both macroscopic and microscopic lesion formation, gastric intramural pH, index of oxygen saturation and index of hemoglobin saturation of the gastric mucosa was studied. To assess the severity of gastric mucosal ischemia, intramural pH was directly measured using a pH sensitive microelectrode and indirectly by utilizing hollow viscus tonometry, and the indices of oxygen saturation and hemoglobin saturation were measured by reflectance spectrophotometry. Oxygenated perfluorochemicals (30 ml/kg/h) significantly protected the gastric mucosa against both gross (lesion index 0.85 +/- 0.2 vs 2.23 +/- 0.31) and microscopic (lesion index 0.52 +/- 0.02 vs 2.04 +/- 0.03) injuries. This protection was associated with a significantly decreased acidification of the mucosa during shock (intramural pH 7.24 +/- 0.02 vs 6.97 +/- 0.02) and significantly increased oxygen saturation of the gastric mucosa (30 +/- 6 vs 5 +/- 2). These data indicate that topical oxygenated perfluorochemicals protect the gastric mucosa against mucosal damage provoked by hemorrhagic shock, and this protection seems to be mediated by an increased oxygen saturation of the gastric mucosa. Tonometry and reflectance spectrophotometry thus are able to predict the critical level of gastric mucosal ischemia.