The effect of phenobarbital on asphyxia of the newborn monkey

Fourteen newborn monkeys (M. speciosa, 2–6 days old) were asphyxiated; 8 were pretreated with phenobarbital and 6 were untreated controls. The treated group received 10 mg/kg I.M. twice prior to the asphyxiation; only one of the infants was not clinically sedated. After 5 minutes of total asphyxia (blocked endotracheal tube) there was a significant mixed respiratory and metabolic acidosis associated with a profound decrease in cardiac output (C.O. ml/min/kg microsphere withdrawal method). Regional blood flow (% C.O.) to the brainstem, midbrain, cerebellum (total of these 3 areas identified as Brain in table) and the heart increased; the % C.O. distributed to the G.I. tract and kidneys decreased. These effects of asphyxia were not significantly modified by phenobarbital.

Acid-base parameters, O₂ consumption (VO₂-kipp diaferometer), blood pressure, cardiac output, and the regional distribution of the cardiac output were determined for phenobarbital treated and control groups prior to axphyxiation; no significant differences were observed.