Effect of Dobutamine on splanchnic carbohydrate metabolism and amino acid balance after cardiac surgery

Background: As a predominant β-adrenergic agonist, dobutamine may modify blood flow distribution and increase metabolic demands. The authors investigated the effect of a dobutamine-induced increase in cardiac output on splanchnic and femoral blood flow and metabolism in patients after cardiac surgery. Methods: Seventeen stable patients were randomized to receive dobutamine or placebo (n = 8 per group, one dropout). After baseline measurement for systemic, splanchnic, and femoral blood flow (by dye dilution); oxygen consumption; gastric mucosal pressure of carbon dioxide (P co2 ); total and splanchnic glucose production (by stable isotope tracer dilution); and regional lactate and amino acid balance, patients received either dobutamine, at a dosage (6 μg-kg -1 min -1 ) sufficient to increase cardiac index by at least 25%, or placebo. A second set of measurements was performed 60 min after the start of dobutamine or placebo infusion. Results: Dobutamine increased cardiac index (3.0 ± 0.6 to 4.4 ± 1.0 l-min -1 m -2 , mean ± SD; P < 0.05), splanchnic blood flow (from 0.8 ± 0.2 to 1.0 ± 0.2 l-min -1 m -2 ; P < 0.05), femoral blood flow (from 0.2 ± 0.1 to 0.3 ± 0.1 l-min -1 m -2 ; P < 0.05), and the arterial-gastric mucosal P co2 gap (from 11.4 ± 9.5 to 11.9 ± 8.0 mmHg; P < 0.05). Dobutamine increased systemic oxygen consumption (from 132 ± 14 to 146 ± 13 ml-min -1 -m -2 ; P < 0.05) but not splanchnic or femoral oxygen consumption. Splanchnic glucose production and lactate and amino acid balance did not change. Conclusion: After coronary artery bypass surgery, dobutamine increased systemic and regional blood flow and decreased systemic and regional oxygen extraction. Dobutamine did not affect splanchnic glucose production or lactate or amino acid balance. This suggests that dobutamine increases splanchnic blood flow without a concomitant increase in hepatosplanchnic metabolism.