Dopamina

Increasing Renal Blood Flow* : Low-Dose Dopamine or Medium-Dose Norepinephrine
David Di Giantomasso, Hiroshi Morimatsu, Clive N. May and Rinaldo Bellomo Chest 2004;125;2260-2267 DOI 10.1378/chest.125.6.2260 The online version of this article, along with updated information and services can be found online on the World Wide Web at: http://chestjournal.chestpubs.org/content/125/6/2260.full.htmlChest is the official journal of the American College of Chest Physicians. It has been published monthly since 1935. Copyright2004by the American College of Chest Physicians, 3300 Dundee Road, Northbrook, IL 60062. All rights reserved. No part of this article or PDF may be reproduced or distributed without the prior written permission of the copyright holder.(http://chestjournal.chestpubs.org/site/misc/reprints.xhtml) ISSN:0012-3692

Downloaded from chestjournal.chestpubs.org at Memorial University on November 11, 2010 © 2004 American College of Chest Physicians

Increasing Renal Blood Flow*
Low-Dose Dopamine or Medium-Dose Norepinephrine
David Di Giantomasso, MD; Hiroshi Morimatsu, MD; Clive N. May, PhD; and Rinaldo Bellomo, MD

Background and objectives: Many cliniciansbelieve that low-dose dopamine (LDD) [2 g/kg/min] increases renal blood flow (RBF) and medium-dose norepinephrine (MD-NE) [0.4 g/kg/min] decreases RBF. They also believe that MD-NE might induce mesenteric and/or coronary ischemia. In fact, the effects of these drugs on renal and vital organ blood flow are poorly understood. The aim of this study was to compare the effects of 6 h of IV LDD and MD-NEinfusion on mammalian renal, coronary, mesenteric, and sagittal blood flow. Design: Randomized, controlled, experimental animal study. Setting: Animal laboratory of tertiary physiology institute. Subjects: Seven Merino cross sheep were studied. Measurements and results: We performed a staged insertion of transit-time flow probes around ascending aorta, sagittal sinus and circumflex coronary, superiormesenteric, and left renal arteries. We then randomized these animal with long-term embedded flow probes to either 6 h of placebo (saline solution) or drugs (MD-NE at 0.4 g/kg/min or LDD at 2 g/kg/min), and performed continuous measurement of systemic pressures, cardiac output (CO), and flow to vital organs. We also sampled blood and urine for the measurement of lactate, creatinine, and creatinineclearances at preset intervals. Results: Compared to placebo, LDD did not affect systemic hemodynamics. However, it increased mean RBF by 20% (267.3 87.6 mL/min vs 222.0 74.4 mL/min, p 0.028) without a detectable effect on other vital regional circulations. MD-NE, however, increased mean arterial pressure (101.0 8.3 mL/min vs 84.2 5.2 mL/min, p 0.018) [mean SD] and CO (4.93 1.45 L/min vs 3.810.57 L/min, p 0.028). It also increased coronary blood flow (36.0 15.7 mL/min vs 23.0 10.7 mL/min, p 0.018) and RBF (286.5 79.0 mL/min vs 222.0 74.4 mL/min, p 0.018). MD-NE had no detectable effect on mesenteric or sagittal sinus flow. LDD infusion increased urine output, but did not change creatinine clearance. MD-NE infusion increased urine output significantly more than LDD but not creatinineclearance. Conclusions: Both LDD (2 g/kg/min) and MD-NE (0.4 g/kg/min) increased RBF and urine output. However, the effect of MD-NE was more pronounced. LDD did not affect other vital organ flows, but MD-NE increased coronary blood flow without any changes in mesenteric and sagittal sinus blood flow. (CHEST 2004; 125:2260 –2267)
Key words: BP; cardiac output; coronary circulation; creatinineclearance; dopamine; mesenteric circulation; norepinephrine; renal circulation Abbreviations: CO cardiac output; EMF electromagnetic flow; HR heart rate; LDD low-dose dopamine; MAP mean arterial pressure; MD-NE medium-dose norepinephrine; RBF renal blood flow; TPC total peripheral conductance

dopamine (LDD) is L ow-doserenal blood flow (RBF)prescribed to increase and attenuate or prevent renal...