By inducing developmentally regulated dose-dependent cardiovascular, renal, and endocrine effects, dopamine (DA) increases blood pressure (BP) and urine output in the hypotensive and/or oliguric neonate (Seri I, J Pediatr 126:333-344, 1995). In adults, the drug-induced selective renal and mesenterial vasodilation contributes to the beneficial effects of DA. However, no study has confirmed the presence of these selective vascular dopaminergic effects in neonates.

We compared the vascular responses to DA in the renal (RA); superior mesenteric (SMA), and middle cerebral (MCA) artery in five non-hypotensive, ELBW neonates (GA=25.2±1.48, range=23-27 weeks; BW=731±158, range 461-857 g) during the first two days of life who presented with respiratory distress syndrome and poor peripheral perfusion. Blood flow velocity profile was measured by Acuson XP color and a duplex Doppler unit with a 5.0/7.0 Mhz Sector Probe at a close to zero angle. The pulsatility index (PI = peak systolic velocity - lowest diastolic velocity divided by the mean velocity) was used to assess the drug-induced selective alterations in the renal (RBF), mesenteric (MBF), and cerebral (CBF) blood flows at a DA dose(2.5-7.5 μg/kg/min) which raised BP by ≈20% and improved peripheral perfusion. Two infants were on Indocin for PDA during the study. The Table summarizes the findings (means±SD).

Table 1
Full size table

Interestingly, Indocin did not attenuate the DA-induced increase in RBF.

Conclusions: 1) In normotensive ELBW infants with poor peripheral perfusion(compensated shock), RBF is compromised. 2) In these neonates, the DA dose which raises BP by ≈20% selectively increases RBF while MBF and CBF remain unchanged. This finding is the first demonstration of a functionally mature renal vascular dopaminergic response in the ELBW neonate, and also suggests that the maturation of their mesenteric vascular dopaminergic system lags behind that of the kidney. 3) As expected, DA, at the doses applied, does not affect CBF.