The hemodynamic effects of dobutamine infusion in the chronically instrumented newborn piglet.
OBJECTIVE
To determine the systemic, pulmonary, mesenteric, and renal hemodynamic effects of short and prolonged infusions of dobutamine.


METHODS
Prospective randomized unblinded study.


METHODS
University research laboratory.


METHODS
Thirteen newborn (1-3 days old) piglets.


METHODS
Piglets were instrumented and studied 48 hrs later. Fifteen-minute infusions of dobutamine at 5, 10, 20 and 50 microg/ kg x min were randomly given with 15-min rests between the doses. After a 1-hr hiatus, a dose of 10 microg/kg x min was continuously administered for 2 hrs.


RESULTS
Systemic and pulmonary arterial pressures, cardiac index (thermodilution), and superior mesenteric and renal artery flows were measured. Vascular resistance values were calculated.


RESULTS
Fifteen-minute infusions: Dobutamine dose-dependently increased cardiac index with tachycardia but not stroke volume (from 187 +/- 43 to 238 +/- 51 mL/kg x min at baseline and 50 microg/ kg x min, respectively, p < .05; values expressed as mean +/- SD). Systemic, but not pulmonary, vascular resistance decreased, resulting in a significant decrease in systemic to pulmonary arterial pressure ratio (from 3.8 +/- 0.8 at baseline to 3.2 +/- 1.0 at 50 microg/ kg x min). Superior mesenteric and renal flows were not affected. Two-hour infusion at 10 microg/kg x min: Cardiac index progressively increased from 173 +/- 34 to 240 +/- 58 mL/kg x min at baseline and 120 mins, respectively, (p < .05). The initial tachycardia was transient, and stroke volume was significantly increased at 60 mins and thereafter. Although systemic and pulmonary vascular resistance values fell simultaneously, systemic to pulmonary arterial pressure ratio decreased significantly to 3.4 +/- 0.9 at 120 mins from 3.9 +/- 0.7 at baseline. Superior mesenteric and renal artery flows increased significantly with vasodilation after 60 mins.


CONCLUSIONS
Short infusions of dobutamine dose-dependently increase cardiac output due to tachycardia, without significant effect on mesenteric and renal blood flows. Prolonged infusion of dobutamine at 10 microg/kg x min progressively increases cardiac output and stroke volume with transient tachycardia, and increases mesenteric and renal blood flows. Caution is required in the treatment of critically ill neonates with dobutamine, which could also reduce systemic to pulmonary arterial pressure ratio.
Cheung
P Y
PY
Department of Pediatrics, University of Alberta, Edmonton, Canada.
Barrington
K J
KJ
Bigam
D
D
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002316:Cardiotonic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D004280:Dobutamine / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics / Q000187:drug effects*; D007262:Infusions, Intravenous; D011897:Random Allocation; D012079:Renal Circulation / Q000187:drug effects; D013552:Swine; D013815:Thermodilution
D002316:Cardiotonic Agents; D004280:Dobutamine