RESPONSE TO DOBUTAMINE AND DOPAMINE IN THE HYPOTENSIVE VERY PRETERM INFANT

A randomised double blind study was designed to evaluate haemodynamic response to dobutamine and dopamine in 20 hypotensive preterm infants of less than 32 weeks' gestation. Neonates initially received dopamine or dobutamine 5 mug/kg/min. If mean arterial pressure (MAP) remained below 31 mm Hg, the infusion rate was increased in increments of 5 mu/ kg/kg/min. If 20 mug/kg/min of the initial drug failed to achieve a MA P above 30 mm Hg, it was discontinued and the other drug was administe red at the same infusion rate. Left ventricular output (LVO) was measu red by pulsed Doppler echocardiography. Mean (SE) MAP increased signif icantly from 24.4 (1.0) to 32.0 (1.4) mm Hg at a median dobutamine dos age of 20 mug/kg/min and from 25.6 (1.2) to 37.7 (1.5) mm Hg at a medi an dopamine dosage of 12.5 mug/kg/min. The percentage LVO increase was +21 (7)% with dobutamine compared with -14 (8)% with dopamine. Dobuta mine failed to increase MAP above 30 mm Hg in six infants out of 10, w hereas dopamine succeeded in all 10 infants. Six switches from dobutam ine to dopamine were thus performed, providing a rise in MAP (29.2 (0. 5) to 41.2 (2.0) mm Hg) and drop in LVO (356 (40) to 263 (36) ml/kg/mi n). These data indicate that dopamine is more effective than dobutamin e in raising and maintaining MAP above 30 mm Hg; however dopamine does not increase LVO.