Effects of phenobarbital on cerebral hemodynamics in preterm neonates

The effect of phenobarbital on cerebral blood flow velocity (CBFV) was studied in 12 clinically stable preterm neonates to evaluate possible mechanisms underlying its protective effect on intracranial hemorrhage. Phenobarbital at loading doses of 20 mg/kg, or placebo (saline) were given intravenously. The study was a cross-over study, each infant successively received placebo, then phenobarbital. Simultaneous recording of heart rate, mean arterial blood pressure (MABP), blood gases were made before, at the end of the injection, and at 15, 30, 60, 90 and 120 min after the end of each administration of either placebo or phenobarbital. Compared with placebo, phenobarbital injection was not associated with significant changes in CBFV and MABP. Heart rate, blood gases did not change significantly. Our data suggest that the protective effect of phenobarbital may minimally be mediated by a direct effect on cerebral blood flow.