The effect of dobutamine on distal colon ischaemia in the pig.

OBJECTIVE

To test the hypotheses that dobutamine increases intestinal blood flow, it reduces mucosal acidosis and it prevents mucosal injury in an experimental porcine model of distal colonic ischaemia. And the hypothesis that mannitol prevents reperfusion injury.

DESIGN

Randomised animal experiment.

SETTING

University Hospital, Department of Experimental Research.

MATERIALS

Twenty-four pigs.

INTERVENTIONS

Twenty-one pigs were subjected to 7 h of controlled non-occlusive intestinal ischaemia of the distal colon, consisting of an occlusion of the inferior mesenteric artery (IMA) and a constriction of the superior mesenteric artery (SMA). At 3.5 h six pigs were treated with dobutamine, six with mannitol (0.18 g/kgBW), six with dobutamine and mannitol and three served as controls. Three non-ischaemic pigs were treated with dobutamine.

MEASUREMENTS AND RESULTS

All animals were haemodynamically stable throughout the experiment. There was no difference in any variable between the animals treated with mannitol and those not treated. The ischaemic dobutamine-treated animals increased their cardiac output (CO) by 14% compared to baseline and by 59% compared to controls. The median final dosage of dobutamine was 13.2 micrograms/kg per min (range 8.6-25.8). The blood flow in the restricted SMA, the intramucosal pH of the colonic mucosa (pHi) and the degree of histological mucosal injury were identical in animals treated with dobutamine and controls. The pH gap (pHa-pHi) correlated well (r = 0.97) with the PCO2 gap (aPCO2-intestinal PCO2). The non-ischaemic animals treated with dobutamine increased CO by 37% and blood flow of the SMA by 16%.

CONCLUSIONS

Dobutamine increased CO but did not ameliorate or deteriorate colonic ischaemia in this experimental model. The PCO2 gap correlated well with the pH gap.