Adverse effects of early phenobarbital administration in term newborns with perinatal asphyxia

Taking advantage of the lack of consensus in our neonatal unit regarding the early (prior to the onset of signs of hypoxic-ischaemic encephalopathy) administration of phenobarbital to term infants with perinatal asphyxia, we evaluated the possible cerebral sparing effect of phenobarbital by doing a retrospective case-control analysis. Fifty-seven infants who received 10 mg/kg loading dose of phenobarbital within one hour following resuscitation and before the onset of signs of hypoxic-ischaemic encephalopathy were compared with 91 infants who did not to determine the effect of early phenobarbital on the incidence of subsequent seizures, and mortality in the perinatal period. Early phenobarbital was associated with a threefold (P < 0.025) increase in the incidence of subsequent seizures, and consequently a trend towards increased mortality. Seizures per se were associated with almost a 20-fold increase in mortality (P < 0.0001). These findings suggest that early phenobarbital administration may produce adverse rather than beneficial effects following asphyxia. Because this is an observational study; these results need to be confirmed by appropriate randomized trials in similar clinical settings.