The clinical use of dopamine in the treatment of shock.

Dopamine is a direct-acting catecholamine with a short half-life that has many advantages in treating visceral hypoperfusion states such as shock and refractory heart failure. Unlike other inotropic drugs, dopamine directly dilates the mesenteric, renal, and cerebral vessels and redirects blood flow to essential viscera. This dopaminergic effect is prominent with doses of 100-700 mug/min in adults and is attenuated by phenothiazines and haloperidol. At doses of 700-1400 mug/min, dopamine also has a significant beta-adrenergic, inotropic effect, increasing myocardial contractility. The inotropic effect is equivalent to that of isoproterenol, epinephrine, and norepinephrine, but tachycardia, tachyarrhythmias, and angina may be less frequent with dopamine. In doses greater than 1400 mug/min, dopamine is a vasoconstrictor with pressor effects usually equivalent to that of norepinephrine. Dopamine dilates pupils, does not dilate bronchi, and does not shunt blood from viscera to skeletal muscles as does isoproterenol. Because dopamine increases myocardial contractility, selectively redistributes perfusion to essential viscera and allows a pharmacologic titration of effect, it is a logical first-choice catecholamine for treatment of shock and refractory heart failure.