1388 EFFECT OF PHENOBARBITAL ON CEREBRAL BLOOD FLOW AND ARTERIAL BLOOD PRESSURE IN THE NEWBORN BEAGLE

Abstract

Phenobarbital sodium (PBS) in anticonvulsant dosage has been administered to high risk newborn prematures in an effort to prevent intraventricular hemorrhage (IVH). The hypothesis has been that PBS may prevent increases in arterial blood pressure (ABP) and cerebral blood flow (CBF). Using radioactive microspheres, we have assessed the effect of PBS at serum concentrations of 24.9 ± 5.0 ug/ml on regional CBF during steady state (SS), during hypovolemic hypotension (HH), during blood reinfusion (RE), and during phenylephrine induced hypertension (PH) in ketamine anesthetized beagle puppies from 24-84 hours of age. There were no significant differences for CBF in steady state with or without PBS (n=9, n=8), or during moderate HH (ABP decreased 35-40%) with or without PBS (n=9, n=8). With PBS blood flow increased to all regions during RE (significant in all but cortex and white matter, n=8); controls had similar increases in all regions during RE, significant in all but the thalamus (n=9). Blood flow during PH increased in all regions with or without PBS (n=5, n=8). Steady state ABP was 64.2 ± 9.8 mmHg. ABP after PBS was 42.5 ± 8.3 mmHg (p < .01). Thus, in the newborn puppy, PBS at anticonvulsant concentrations reduced arterial blood pressure but did not alter the response of cerebral blood flow. Its effect on the incidence of periventricular hemorrhages in the newborn beagle is under current study.