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CARDIOVASCULAR
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Volume 6, 2001, No 1 |
The
Effects of Dopamine, Epinephrine and Dobutamine in the Newborn Piglet During
Normoxia and Hypoxia
K. J. Barrington
Background:
Neonatal inotrope responses differ from those in the adult, because of
functional differences in the myocardium, structural immaturity of the heart and
blood vessels, and incomplete development of receptor systems.
Methodology:
A series of experiments in acutely and chronically instrumented, 1 to 3 day old,
piglets to describe effects of dopamine, dobutamine and epinephrine, during
normoxic and hypoxic conditions.
Results:
During normoxia, dopamine increased systemic and pulmonary blood pressures
equivalently, and increased cardiac output; when blood pressure increases
sufficiently, cardiac output falls. During hypoxia there was no effect on
cardiac output. There was no selective renal vasodilatation with dopamine, or
with selective dopamine agonists, and at higher doses renal vasoconstriction
occurred. Blood flow to the bowel was unaffected by dopamine. There was no
direct effect of dopamine on coronary perfusion.
Epinephrine increased both blood pressure and cardiac output at low or moderate
doses, there was a lesser effect on the pulmonary vasculature during both
normoxia and hypoxia. Renal perfusion was unaffected by epinephrine until very
high doses were used; mesenteric perfusion also fell at these doses. Coronary
vascular resistance decreased with epinephrine.
Dobutamine increased cardiac output but only increased blood pressure at very
high doses, renal and bowel perfusion were unaffected by short term infusions,
but both increased during more prolonged therapy.
There is inadequate information about the effects of any of these drugs on
cerebral perfusion; carotid blood flow was increased by both dopamine and
epinephrine.
Conclusions: Rational use of these catecholamine inotropic agents in the newborn subject will require further study.
(CVE. 2000; 6 (1): 44-50)
Key words: catecholamines, dopamine, dobutamine, epinephrine, piglet, hypoxia
Keith
J. Barrington, M.D.
Department of Pediatrics
University of Californi
San Diego
200 W Arbor Dr.
8774, San Diego
CA 92103-8774
USA
E-mail: kbarrington@ucsd.edu
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