247 CARDIAC OUTPUT AND HYPOTENSION IN PRETERM INFANTS WITH RESPIRATORY DISTRESS SYNDROME

Abstract

To evaluate the effects of inotropic support on cardiac function and blood pressure in preterm hypotensive infants, we compared 56 preterm infants with respiratory distress syndrome (RDS) (FiO2>40%) to 27 preterm infants without RDS at 8-72 h of age. In the controls, mean ± SEM birth weight was 1285±47 g, gestational age 30.9±.3 wks, mean blood pressure (MBP) 45±1 mm Hg, CO 319±11 ml/min/kg, and systemic vascular resistance (SVR) 132 ± 7 mm Hg/L−2min/kg. In the RDS group, these values were 1050±45 g (p<0.001), 28.9±.4 wks (p=0.002), 36±1 mm Hg (p<0.001), 358±15 ml/min/kg, and 107±8 mm Hg/L−1/min/kg. 26 (46%) RDS infants received dopamine, in 12 (21%) combined with dobutamine, and 29% had a MBP ≤30 mm Hg. CO in hypotensive and normotensive RDS infants was similar. In the RDS group, MBP was 37±3 mm Hg and SVR 243±51 mm Hg/L−1min/kg in the low CO (≤250 ml/min/kg) subgroup and 32±2 mm Hg and 52±4 mm Hg/L−1/min/kg in the high CO (≥410 ml/min/kg) subgroup (p<0.001 vs controls). Treatment of RDS infants with dopamine or dopamine + dobutamine raised MBP to values similar to those not receiving inotropic support, but addition of dobutamine significantly increased CO and reduced SVR. These data indicate that whereas dopamine mainly affects blood pressure, dobutamine added onto dopamine simultaneously increases CO, leading to a reduction in SVR.