Effects of dopamine and dobutamine on regional blood flow distribution in the neonatal piglet.

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OBJECTIVE: The authors determined the effects of dopamine and dobutamine on organ blood flow in newborn piglets. SUMMARY BACKGROUND DATA: Although the hemodynamic effects of dopamine and dobutamine are well described in adults, little is known of their consequences in neonates, and their impact on organ perfusion in premature infants is unclear. METHODS: Cannulae were placed in the femoral vessels and left atrium of term (1-14 days old) and prematurely delivered (Ceasarean section at 90% of term gestation) piglets. After stabilization, radiolabeled microspheres were injected. A continuous infusion of dopamine or dobutamine was started, and other microspheres were injected at 5, 10, and 15-micrograms/kg/minute drug doses (allowing a 20-minute equilibration period at and between each dose). Blood flows (mL/minute/g tissue) to organs were determined using reference organ techniques. RESULTS: In term animals only, dobutamine and dopamine increased systemic mean arterial pressure at the 15-micrograms dose. In term piglets, dobutamine produced dose-dependent increases (p < 0.05, analysis of variance) in heart and brain blood flow, although small intestinal blood flow decreased (1.47 +/- 0.13 mL/minute/g baseline to 1.31 +/- 0.11 mL/minute/g at 15-micrograms dose). There were no significant changes in blood flow to these organs in preterm animals. Dopamine significantly (p < 0.05) increased heart blood flow in both groups. Dopamine also increased small intestinal blood flow in term (1.63 +/- 0.22 mL/minute/g baseline to 3.13 +/- 0.34 mL/minute/g at 15-micrograms dose) and premature (0.31 +/- 0.10 mL/minute/g baseline to 1.11 +/- 0.29 at 15 micrograms dose) piglets. CONCLUSIONS: Dopamine may prove a valuable adjunct when a premature infant is at risk for conditions that reduce alimentary tract blood flow.

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