Effects of fluid and dobutamine treatment on renal function during partial superior mesenteric artery occlusion and reperfusion

OBJECTIVE: We compared the effects of dobutamine, fluid resuscitation and their combination on renal function during experimental intestinal ischaemia and reperfusion. MATERIALS AND METHODS: Superior mesenteric artery (SMA) blood flow was reduced to 30% from the baseline for 120 minutes in 24 anaesthetized pigs (ischaemic group); 24 pigs (sham group) served as non-ischaemic controls. The animals were further assigned into four treatment arms. In the control arms, the animals were given only basic fluid therapy. In the fluid therapy arms, pulmonary capillary wedge pressure (PCWP) was maintained at 10 mmHg with intravenous fluids. In the dobutamine treatment arm, dobutamine hydrochloride was infused at a dose of 10 microg/min/kg. In the combined dobutamine-fluid therapy arms, dobutamine at 10 microg/min/kg was given and PCWP was maintained at 10 mmHg with fluids. At 120 minutes, the occluder was released in all study groups and the animals were followed for an additional 60 minutes. Renal function was evaluated by means of serum and urine creatinine. urine volume and creatinine clearance. Systemic and regional haemodynamics as well as intramucosal pH, intramucosal-arterial pCO2 gradient, and portal venous-arterial lactate gradient were measured. RESULTS: In the ischaemic groups, diuresis increased and serum and urine creatinine decreased significantly in fluid (p < 0.01, p < 0.01 and p < 0.05, respectively) and dobutamine-fluid (p < 0.01, p < 0.001 and p < 0.001, respectively) treated groups during SMA ischaemia. After SMA reperfusion, diuresis decreased in control group (p < 0.05) and in animals treated with dobutamine alone (p < 0.01). In addition, urine creatinine increased in dobutamine treated group (p < 0.05), and creatinine clearance decreased in control group (p < 0.01). Renal function and diuresis during the SMA occlusion and reperfusion did not differ between ischaemic and sham groups. All fluid treated groups had lower serum creatinine during SMA occlusion than control groups (p < 0.001). CONCLUSIONS: Intestinal ischaemia caused by partial SMA occlusion did not influence renal function. On the contrary, SMA reperfusion resulted in a significant impairment of renal function both in ischaemic and sham operated animals. The impairment was most obvious in control groups and in animals treated with dobutamine alone.