Gut mucosal perfusion in infants undergoing cardiopulmonary bypass: Effect of preoperative captopril

We have studied gut mucosal perfusion in 24 infants, aged 0.7-45 weeks, requiring cardiopulmonary bypass (CPB). Group 2 patients (n=12) had received the angiotensin converting enzyme inhibitor captopril 0.8-0.9 mg kg(-1) orally, 45 min before induction of anaesthesia. Group 1 infants were of similar age and size and required a similar duration of CPB, but did not receive any preoperative medication. An orogastric tonometer allowed intermittent calculations of gastric intramucosal pH (pH(i)), and rectal mucosal perfusion (''flux'') was monitored using laser Doppler flowmetry. Measurements of arterial base deficit and lactate and pyruvate concentrations were made intermittently. We found no significant difference in femoral arterial pressure between the groups at any time before, during or after surgery. Similarly, we found no significant differences in our measures of regional or global tissue perfusion between the groups at any time before, during or after surgery. We conclude that preoperative administration of captopril produced no beneficial effect on gut mucosal perfusion in infants undergoing hypothermic, non-pulsatile CPB.