Prolonged infusion of varied doses of dopexamine hydrochloride for low cardiac output after cardiac surgery.

Circulatory failure after cardiac surgery often calls for active hemodynamic management with fluids, inotropes, and vasodilators. Dopexamine hydrochloride is a new combined beta 2-adrenergic and DA1-dopaminergic receptor agonist and an inhibitor of the uptake-1 mechanism of endogenous catecholamines. As a result, it exerts inotropic and vasodilator effects on the heart and systemic vasculature. The effects were examined over a mean of 22 hours, using 1 to 4 micrograms/kg/min of dopexamine to treat low cardiac output states following coronary bypass and valvular/ventricular repair surgery. In 8 out of 14 patients, low cardiac output was readily reversed by 1 microgram/kg/min of dopexamine. Six patients required higher doses (2 to 4 micrograms/kg/min) to achieve a satisfactory cardiac index. Significant changes from control values were observed throughout the infusion for heart rate (67 to 102 beats/min), cardiac index (2.0 to 3.4 L/min/m2), and systemic vascular resistance (1,545 to 914 dyne.s.cm-5). Pulmonary vascular resistance, pulmonary artery wedge pressure, and right atrial pressure were also significantly reduced during the infusion. Most of these changes reversed when dopexamine was discontinued, suggesting a drug-specific effect and a lack of tolerance. Nausea was a frequent complaint, but was no more frequent than in a random sample of similar patients. Titration of dopexamine, 1 to 4 micrograms/kg/min, was efficacious in producing circulatory improvement in patients with a low cardiac output after cardiac surgery.