Effects of dopamine on oxygen consumption and gastric mucosal blood flow during cardiopulmonary bypass in humans

We investigated the effects of flow rate and dopamine on systemic oxygendelivery (DO2) oxygen consumption (VO2) and gastric mucosalmicrocirculatory blood flow (gMCF), measured by laser Doppler flowmetry in12 patients undergoing mild hypothermic (34 degrees C) cardiopulmonarybypass (CPB). The first intervention comprised increasing CPB flow ratesfrom 2.4 to 3.0 litre min-1 m-2, and the second intervention administeringdopamine 6 micrograms kg-1 min-1. Measurements were made before and 10 minafter the start of one of the two interventions. The heart remained incardioplegic arrest throughout the study. There were no significantdifferences in variables between the two baseline measurements precedingthe interventions. The increase in CPB flow rate increased DO2 and gMCFwithout affecting VO2. At constant flow rate, dopamine also increased gMCFwith no change in VO2, DO2 or mean arterial pressure. Our data suggestedthat dopamine had no flow-independent effect on VO2 and that it increasedgMCF during constant flow hypothermic CPB.