[Prevention of hypoxic-ischemic encephalopathy with high-dose, early phenobarbital therapy]

To assess usefulness of high-dose early phenobarbital therapy for prevention of hypoxic-ischemic encephalopathy (HIE) secondary to perinatal asphyxia (PNA).

By means of a randomized clinical trial, asphyxiated full-term or post-term newborn infants were divided in two groups: Group A was the experimental group, while group B was the control group. Infants in group A received phenobarbital, 40 mg/kg, during the first 60 min after birth. Infants on group B received phenobarbital at conventional doses, only if there was clinical evidence of seizures; otherwise, treatment was similar in both groups. We estimated frequency of HIE according to Sarnat classification and also rate of post-asphyxial complications in other organs. Phenobarbital levels were measured in Group A. Statistical tests used were Student t, Mann-Whitney U, X2 or Fisher. Informed consent was obtained from parents of each infant.

37 infants belonged to Group A, while Group B was composed of 36 infants. Both groups were similar in sex, gestational age and cord gases. Birth weight was higher in Group A (p<0.05). Diagnostic criteria for PNA a cord pH < or = 7.00 plus one or two criteria of commonly used parameters for asphyxia. There was a difference in total dose of phenobarbital and time of initial dose in both groups. HIE was present in 13.5% (5/37) of group A, and 22.2% (8/36) of group B. Seizures (Stage II of HIE) occurred in 10.8% (4/37) and 11.1% (4/36), respectively, without significant statistical difference. There was also no difference in rate of post-asphyxial, non-brain complications in both groups. There were no side effects or changes in vital signs associated with use of phenobarbital. Only one infant had toxic phenobarbital serum levels.

There was no significant difference in the overall frequency of HIE, nor in the incidence of seizures or stage II of HIE in both groups. According to these results and even though there were no side effects, we think phenobarbital is not useful for these purposes. Long-term follow-up of the treated infants is justified, since phenobarbital might have a beneficial effect on neuro-behavioral development.