ASSESSMENT OF SPLANCHNIC OXYGENATION BY GASTRIC TONOMETRY IN PATIENTSWITH ACUTE CIRCULATORY FAILURE

Objective.- To investigate the importance of splanchnic ischemia in pa tients with acute circulatory failure by comparing gastric intramucosa l pH as measured by tonometry with conventional methods of assessing a dequacy of tissue oxygenation. Design.- Prospective cohort of patients with acute circulatory failure in first 24 hours after admission to t he intensive care unit. Setting.- Two general intensive care units in London, England. Patients.- Consecutive sample of 83 patients of varyi ng diagnostic categories that required pulmonary artery catheterizatio n. Main Outcome Measures.- Gastric intramucosal pH and hemodynamic, ox ygen transport, and metabolic variables were measured on admission and at 12 hours and 24 hours after admission. Prediction of outcome (deat h or survival) by each measurement was assessed by sensitivity, specif icity, and logistic regression analysis. Results.- Mean 24-hour Acute Physiology and Chronic Health Evaluation (APACHE II) score was 20.3. T here were significant differences in mean gastric intramucosal pH betw een survivors and nonsurvivors on admission and at 24 hours, (7.40 vs 7.28, 7.40 vs 7.24, respectively; P<.001). Admission heart rate was hi gher (116 vs 101 beats per minute; P<.003) and mean arterial pressure lower (82 vs 97 mm Hg; P<.01) in nonsurvivors. There were no consisten t differences in cardiac index, oxygen delivery, and oxygen uptake bet ween survivors and nonsurvivors. Admission arterial pH was significant ly lower (7.3 vs 7.36; P<.003), base excess more negative (-5.3 vs - 1 .9; P<.001), and lactate concentration higher (3.14 vs 1.91 mmol/L; P< .03) in nonsurvivors. Gastric intramucosal pH had a sensitivity of 88% for predicting death and a likelihood ratio of 2.32, higher than for any other variable. Only gastric intramucosal pH at 24 hours independe ntly predicted outcome. Conclusions.- Gastric intramucosal pH was the most reliable indicator of adequacy of tissue oxygenation in this grou p of patients. Inadequate regional blood flow as detected by a reducti on in gastric intramucosal pH, but not by systemic measures, is an imp ortant contributor to morbidity and mortality in intensive care units.