28 EFFECTS OF PHENOBARBITAL ON CEREBRAL HEMODYNAMICS IN PRETERM NEONATES
We evaluated the effect of phenobarbital (pb) versus placebo (saline) on cerebral hemodynamics in eleven, clinically stable preterm neonates. The mean (+SD) post natal age at study entry was 12 (3) hours. The mean (+SD) birth weight and gestational age were 1286 (387 g) and 30.5 (3) weeks respectively. We measured cerebral blood flow velocity (CBFV), using a pulsed wave Doppler monitor. Every subject was his own control. Placebo was systematically injected prior to pb (20 mg.kg −1 over 20 min). Simultaneous recording of heart rate, arterial blood pressure, TcPCO2, TcPO2, SaO2 were made before, at the end of the injection, and a 15, 30, 60, 90, 120 min after the end of each administration of either placebo or pb. Results : pb was in anticonvulsant concentrations (16 to 24 μg/ml). No significant changes ocurred in systemic hemodynamics, or in blood gases. CBFV remains stable and no different during placebo or phenobarbital administration. We conclude that a pb loading dose of 20 mg −1, has no effect on systemic and cerebral hemodynamics during steady state. The cerebral protective action of phenobarbital may not result by decreasing baseline cerebral blood flow as previously suggested.