THE EFFECT OF DOBUTAMINE ON DISTAL COLON ISCHEMIA IN THE PIG

Objective: To test the hypotheses that dobutamine increases intestinal blood flow, it reduces mucosal acidosis and it prevents mucosal injur y in an experimental porcine model of distal colonic ischaemia. And th e hypothesis that mannitol prevents reperfusion injury. Design: Random ised animal experiment. ment. Setting: University Hospital, Department of Experimental Research. Materials: Twenty-four pigs. Interventions: Twenty-one pigs were subjected to 7 h of controlled non-occlusive int estinal ischaemia of the distal colon, consisting of an occlusion of t he inferior mesenteric artery (IMA) and a constriction of the superior mesenteric artery (SMA). At 3.5 h six pigs were treated with dobutami ne, six with mannitol (0.18 g/kgBW), six with dobutamine and mannitol and three served as controls. Three non-ischaemic pigs were treated wi th dobutamine. Measurements ann results: All animals were haemodynamic ally stable throughout the experiment. There was no difference in any variable between the animals treated with mannitol and those not treat ed. The ischaemic dobutamine-treated animals increased their cardiac o utput (GO) by 14% compared to baseline and by 59% compared to controls . The median final dosage of dobutamine was 13.2 mu g/kg per min(range 8.6-25.8). The blood flow in the re stricted SMA, the intramucosal pH of the colonic mucosa (pHi)and the degree of histological mucosal inj ury were identical in animals treated with dobutamine and controls. Th e pH gap (pHa-pHi) correlated well (r = 0.97) with the PCO2 gap (aPCO( 2)-intestinal PCO2). The non-ischaemic animals treated with dobutamine increased CO by 37 % and blood flow of the SMA by 16%. Conclusions: D obutamine increased CO but did not ameliorate or deteriorate colonic i schaemia in this experimental model. The PCO2 gap correlated well with the pH gap.