Effect of dopamine vs norepinephrine on hemodynamics in septic shock. Emphasis on right ventricular performance.

The effects of continuously infused dopamine and norepinephrine on hemodynamics, oxygen metabolism, and right ventricular (RV) performance were studied by crossover design in ten patients with septic shock who needed treatment with vasoactive drugs after fluid replacement. Standard hemodynamic measurements were obtained and RV performance assessed before and 1 h after the start of the infusion. All but one patient had pulmonary hypertension, and in seven the RV ejection fraction (RVEF) was lower than 50 percent at baseline. Drugs were titrated to a systolic arterial blood pressure of mean 106 +/- 18 mm Hg for dopamine and 116 +/- 20 mm Hg for norepinephrine (NS). Dopamine infusion increased the cardiac index (CI) 16 percent (p less than 0.02), but heart rate and systemic and pulmonary vascular resistances were unchanged. With norepinephrine CI was unchanged, a heart rate decreased 7 percent (p less than 0.05), and systemic and pulmonary vascular resistance increased 35 and 26 percent, respectively (p less than 0.05). With both drugs, RV volumes and RVEF remained unchanged, and systemic oxygen consumption increased equally (by 19 percent for dopamine and 22 percent for norepinephrine, p less than 0.05); systemic oxygen delivery rose by 17 percent during dopamine infusion and was unchanged during norepinephrine infusion. Norepinephrine increased oxygen extraction vs dopamine (p less than 0.05). There were no differences in urinary output. Norepinephrine may improve the RV oxygen supply/demand ratio, but this potentially beneficial effect on RV ejection fraction may be offset by a concomitant increase in pulmonary vascular resistance and RV afterload. Norepinephrine may not adversely affect the peripheral circulation. In short-term treatment of volume-resuscitated, severe septic shock complicated by pulmonary hypertension and impaired RV performance, norepinephrine may be at least as effective as dopamine.