No abstract

The effect of low dose (2, 4, and 8 micrograms/kg per min) dopamine infusion on blood pressure, heart rate and renal function was studied in 18 hypotensive, preterm infants with severe hyaline membrane disease (HMD). Significant dose-related effects found during dopamine infusion were systolic and diastolic blood pressure elevation and diuretic effect, while heart rate increase occurred only with 8 micrograms/kg per min of the drug. This indicates, that in the preterm neonate, dopamine at low doses has a pronounced effect on the alpha- and dopamine-receptors, while its beta-receptor stimulating activity is minimal. We demonstrated a significantly decreased metabolic clearance rate of dopamine in preterm infants. Thus, beside the differences in the vascular receptors' maturation, the decreased metabolic clearance rate should also be taken into account when explaining the cardiovascular and renal effects of low dose dopamine infusion in these babies. Dopamine was found to be useful in normalizing low arterial blood pressure, in improving impaired peripheral circulation, and in producing a marked diuresis in hypotensive preterm neonates with severe hyaline membrane disease.

Nine premature infants with birth weight of 1150 to 2500 g and gestational age of 28 to 35 weeks were given dopamine in a dose of 2-4 micrograms/kg/min to treat cardiopulmonary distress. In addition to monitoring of blood gases, blood pressure, acid-base balance, urine flow and urinary sodium excretion, plasma renin activity (PRA) and plasma aldosterone concentration (PA) was also determined prior to and during dopamine therapy. The dopamine-induced increase in urine flow and urinary sodium excretion was associated with a significant increase of PRA from 18.2 +/- 5.1 ng/ml/h to 33.0 +/- 5.6 ng/ml/h (P less than 0.025), while PA and blood pressure remained unaltered by dopamine administration. It is suggested that the angiotensin II-stimulated aldosterone production is overridden by the inhibitory effect of dopamine.