Comparison of hemodynamic and oxygen transport effects of dopamine and dobutamine in critically ill surgical patients.

Hemodynamic and oxygen transport effects of dopamine and dobutamine were studied in a series of 25 critically ill postoperative general surgical patients by a prospective, randomized crossover design after maximal response to fluids had been obtained. Dopamine increased MAP, HR, CI, PvO2, DO2, and Qsp while decreasing PaO2. Dobutamine increased HR, CI, SI, stroke work, DO2, VO2, and Qsp while decreasing PAWP and SVRI and PVRI. In general, the effects of the two drugs were greater in patients in the first 72 hours after surgery. The effects of dobutamine on flow and oxygen transport were greater than those of dopamine, especially in the early postoperative period. The effects were smaller and not significant in patients more than three days after surgery, as well as in those with sepsis, respiratory failure, renal failure, age over 65 years, and hyperdynamic states, in part because of the small number of patients in each group. These data are consistent with the hypothesis that the beta 2-adrenergic action of dobutamine vasodilates the previously constricted peripheral circulation, enhances tissue perfusion by improving micro-circulatory flow distribution, and improves DO2 and VO2.