[Dopexamine: a new catecholamine used in the treatment of low cardiac output after heart surgery].

The value of dopexamine hydrochloride, a beta 2 agonist with dopamine-like and weak beta 1 effects, for the treatment of low cardiac output was investigated in twelve patients. All had undergone cardiac surgery (valve replacement, aorto-coronary bypass), and had a cardiac index (C1) less than 21.min-1.m-2, low urine output (17 +/- 23 ml.h-1), and poor peripheral perfusion (peripheral cyanosis, cold hands and feet). Systolic arterial blood pressure was decreased, but over 80 mmHg. Diastolic pulmonary arterial or wedge blood pressure was more than 15 mmHg. Usual haemodynamic monitoring was carried out using arterial and Swan-Ganz catheters. Dopexamine hydrochloride doses were increased every 15 min by increments of 1 microgram.kg-1.min-1, up to a maximum dose of 8 micrograms.kg-1.min-1, so as to determine the optimal dose for each patient. This dose was then given for a period of up to 48 h. During the initial titration phase, heart rate increased by 37% from control at a dose of 4 micrograms.kg-1.min-1, this increase becoming less important at higher doses (13% at 8 micrograms.kg-1.min-1). Mean arterial blood pressure increased by 13% at a dose of 2 micrograms.kg-1.min-1. Mean pulmonary arterial blood pressure did not change significantly, but wedge pressure fell by 25% at 4 micrograms.kg-1.min-1. Simultaneously, CI increased by 56%, and systemic vascular resistances decreased by 31% (p less than 0.005). During the continuous steady rate infusion period, heart rate fell to a level of about 100 b.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)