A comparison of dopamine, dobutamine and isoproterenol in the treatment of shock

Abstract

Twelve patients in shock, defined as being present if the mean arterial blood pressure was less than 60 mm Hg, pulmonary arterial occlusion pressure was 15 mm Hg or greater, urine output was 20 ml or less for 2 consecutive hours, and there was clinical evidence of poor peripheral perfusion, underwent a comparative therapeutic trial with dopamine at 200 μg · min^-1 and 400 μg · min^-1 (2.5–5.5 μg · kg^-1 · min^-1), dobutamine 250 μg · min^-1 and 500 μg · min^-1 (3.5–7 μg · kg^-1 · min^-1) and isoproterenol 2 μg · min^-1 and 4 μg · min^-1 (0.025–0.055 μg · kg^-1 · min^-1). Isoproterenol at 2 μg · min^-1, produced a significant increase in pulse rate, cardiac output, left ventricular stroke work index and decrease in mean pulmonary blood pressure and pulmonary arterial occlusion pressure and at 4 μg · min^-1 a significant increase in stroke volume, mixed venous oxygen tension and decrease in right atrial pressure and systemic vascular resistance was also observed. Dopamine at 200 μg · min^-1 produced a significant increase in cardiac output, pulmonary arterial occlusion pressure and mixed venous oxygen tension and at 400 μg · min^-1 a significant increase in pulse rate, mean arterial blood pressure mean pulmonary blood pressure, right ventricular stroke work index, right atrial pressure and pulmonary arterial occlusion pressure and decrease in arterial oxygen tension was also observed. Dobutamine at 250 μg · min^-1 produced a significant increase in cardiac output, and at 500 μg · min^-1 a significant increase in pulse rate, mixed venous oxgen tension and decrease in pulmonary arterial occlusion pressure.

All agents increased pulse rate and cardiac output, although in the dosages chosen dopamine was the only agent do so with an increase in pulmonary arterial occlusion pressure and decrease in arterial oxygen tension. In patients in shock if an inotropic agent is considered necessary its pulmonary effect should be considered along with its effect on coronary and peripheral perfusion since dopamine may reduce arterial oxygenation.