EFFECTS OF DOPAMINE AND DOBUTAMINE ON REGIONAL BLOOD-FLOW DISTRIBUTION IN THE NEONATAL PIGLET

Objective The authors determined the effects of dopamine and dobutamin e on organ blood flow in newborn piglets. Summary Background Data Alth ough the hemodynamic effects of dopamine and dobutamine are well descr ibed in adults, little is known of their consequences in neonates, and their impact on organ perfusion in premature infants is unclear. Meth ods Cannulae were placed in the femoral vessels and left atrium of ter m (1-14 days old) and prematurely delivered (Cesarean section at 90% o f term gestation) piglets. After stabilization, radiolabeled microsphe res were injected. A continuous infusion of dopamine or dobutamine was started, and other microspheres were injected at 5, 10, and 15-mu g/k g/minute drug doses (allowing a 20-minute equilibration period at and between each dose). Blood flows (mL/minute/g tissue) to organs were de termined using reference organ techniques. Results In term animals onl y, dobutamine and dopamine increased systemic mean arterial pressure a t the 15-mu g dose. In term piglets, dobutamine produced dose-dependen t 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-mu g dose). Ther e 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 i n term (1.63 +/- 0.22 mL/minute/g baseline to 3.13 +/- 0.34 mL/minute/ g at 15-mu g dose) and premature (0.31 +/- 0.10 mL/minute/g baseline t o 1.11 +/- 0.29 at 15-mu g dose) piglets. Conclusions Dopamine may pro ve a valuable adjunct when a premature infant is at risk for condition s that reduce alimentary tract blood flow.