Effects of dopamine and epinephrine infusions on renal hemodynamics in severe malaria and severe sepsis

Objective: To describe and compare the effects of dopamine and epinephrine in various doses on renal hemodynamics and oxygen transport in patients wit h severe malaria and severe sepsis. Design: Prospective, controlled, crossover trial. Setting: The intensive care unit of an infectious diseases hospital in Viet Nam. Patients: Fourteen patients with severe falciparum malaria and five with se vere sepsis. Interventions: In an open, crossover design, we observed the effects on ren al and systemic hemodynamics and oxygen transport of separate stepped Infus ions of epinephrine and dopamine. We measured renal blood flow (RBF) and ca rdiac output by the thermodilution method using fluoroscopically guided cat heters. Creatinine clearance at each time point was calculated from the ren al plasma flow and the renal arteriovenous difference in plasma creatinine. Measurements and Main Results: Dopamine at a "renal" dose (2.5 mu g/kg/min) was associated with a mean (95% confidence interval) fractional increase i n the absolute renal blood flow index (RBFI) of 37% (13% to 61%) and in RBF as a fraction of cardiac output (RBF/CO) of 35% (10% to 59%; p = .007 and p = .014, respectively). The consequent 39% (14% to 64%) increase in renal oxygen supply (p = .002) was accompanied by a 32% (20% to 44%) decrease in the renal oxygen extraction ratio (p = .0003), leading to no net change in renal oxygen consumption. At higher doses (10 mu g/kg/min), both RBF and RB F/CO were not significantly different from baseline values and decreased fu rther as the dose was reduced again. There was no obvious explanation for t his hysteresis, There was no change in renal oxygen consumption throughout the study. Because lactic acidosis developed, epinephrine was only given to eight of the 19 patients, and the full stepped epinephrine infusion was gi ven to four patients. Epinephrine infusion was associated, both in absolute terms and when compared with dopamine, with a significant increase in rena l vascular resistance (p = .0003 and .0005, respectively), a decrease in RB F/CO (p = .002 and .03), and a compensatory increase in the renal oxygen ex traction ratio (p = .005 and .0001), RBFI and renal oxygen consumption rema ined constant throughout the epinephrine infusion profile. Neither epinephr ine nor dopamine significantly affected creatinine clearance or urine outpu t. Twelve patients (63%) were in established renal failure (plasma creatini ne, >3 mg/dl) at the time of the study, although the presence or absence of renal failure did not significantly influence the effects of the study dru gs. However, overall, the presence of renal failure was associated with a l ower mean renal oxygen consumption, a lower mean renal oxygen consumption a s a fraction of systemic oxygen consumption, and a higher mean renal vascul ar resistance. Conclusion: Although dopamine increased and epinephrine decreased fractiona l renal blood flow, there was no evidence that either drug produced either a beneficial or a deleterious effect on renal oxygen metabolism or function at any of the doses investigated.