Comparison of the effects of dopamine and dobutamine during continuous positive-pressure ventilation.

Abstract

The depressant effects of continuous positive-pressure ventilation (CPPV) on circulatory and renal functions, and their reversal by dopamine (5 μg/kg/min), dobutamine (7.5 μg/kg/min), or a combination of the two drugs (dopamine 2.5 and dobutamine 5 μg/kg/min) were studied in 10 patients with acute respiratory distress syndrome (ARDS) requiring treatment with positive end-expiratory pressure (PEEP). In comparison with a control period of intermittent positive-pressure ventilation (IPPV), CPPV increased arterial oxygen tension (PaO2) by 11%, but decreased the cardiac index (CI) by 21% and systemic oxygen transport (TO2) by 14%. The additional administration of catecholamines resulted in an increase both in CI — by 38% (dopamine), 33% (dobutamine), and 47% (combination) — and in TO2 —by 34% (dopamine), 28% (dobutamine) and 46% (combination). The observed changes in PaO2 were negligible. The changeover from IPPV to CPPV resulted in a marked decrease in urinary output (42%), sodium excretion (52%), and in creatinine clearance (36%). Under dopamine or the combination of dopamine and dobutamine there was a two- to threefold improvement in these parameters as compared with the CPPV figures, while under dobutamine alone, the increases were virtually of the same order as the increase in CI. It may be concluded that both dopamine and dobutamine are suitable for correcting impaired circulatory and renal functions induced by CPPV. Their beneficial effects on circulatory and respiratory parameters are virtually identical. In the presence of renal failure, the use of dopamine or a combination of the two drugs is recommended.