EFFECT OF PHENOBARBITAL ON CEREBRAL BLOOD FLOW AND TOTAL BRAIN OXYGEN CONSUMPTION IN NEWBORN PIGLETS

Abstract

The effect of phenobarbital (Pb) on cerebral blood flow (CBF) and total brain oxygen consumption (TBOC) was studied in 3 groups of awake newborn piglets (ages 1-3.5 d). Group I (control n-9) received saline, Group II (n=9) received low Pb dose (15 mg/kg IV) and Group III (n-9) received high Pb dose (45 mg/kg IV). Four CBF and cardiac output measurements per piglet using radioactive microspheres (¹⁴¹Ce,⁸⁵Sr,⁹⁵Nb,⁴⁶Sc) arterial blood gases, 02 content hematocrit and plasma glucose were obtained at 0,15,30,60 min after saline or Pb injections. In all groups, pH, PO2, PCO2, blood pressure, heart rate, temperature and plasma glucose remained unchanged except a 14% decrease (p<0.05) in BP and an increase (p<0.05) in PCO2 (3 torr) at 60 min in Groups II and III. Total cerebral blood flow (TCBF) in Groups II and III decreased by 13% and 11.5% respectively (p<0.05) at 15 min and was significantly lower (p<0.05) than Group I but returned to baseline 30 min after drug injection. Similar findings were noted in different areas (cerebrum, thalamus, brain stem and eyes). TCBF and TBOC remained unchanged in Group I. In Group II, TBOC decreased by 35% (p<0.01) at 15 min and returned to baseline at 60 min. In Group III, high Pb dose lowered TBOC by 34% at 30 min (p<0.01) which persisted to 60 min. We conclude that therapeutic Pb dose produced only a transient decrease in TCBF and TBOC, but a high dose produced a more important and sustained decrease in TCBF and TBOC.

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