Combined haemodynamic effects of low doses of dopamine and dobutamine in patients with acute infarction and cardiac failure.

The haemodynamic effects of an optimal dose of dobutamine (DUo) (6.7 +/- 4.2 micrograms kg-1 min-1) and the combination of this optimal dose minus 2.5 micrograms kg-1 min-1 of dobutamine (DU) plus dopamine 2.5 micrograms kg-1 min-1 (DA) were studied in a first group of 12 consecutive patients with acute myocardial infarction (AMI) and cardiac failure (CF). DUo decreased pulmonary wedge pressure from 23.5 to 16 mm Hg (P less than 0.01), systemic vascular resistance from 1 774 to 1 417 dynes s cm-5 (P less than 0.01). DUo increased cardiac output from 3.21 to 4.55 litres/min (P less than 0.01) and urinary flow (UF) from 20 to 68 ml/h (P less than 0.01). Heart rate and blood pressure did not change significantly. DUo - DU + DA significantly increased UF from 68 to 107 ml/h (P less than 0.05) while the other parameters remained unchanged with respect to DUo. The positive effect of DA on UF was confirmed in a second group of 12 consecutive patients by comparing the successive effects of DA + DUo and DUo + DU : all previously described parameters remained unchanged except UF which decreased from 107 to 65 (P less than 0.01). We conclude that in patients with CF and AMI, association of DA and DUo is useful in obtaining both inotropic and diuretic effects.