Comparative effect of graded doses of epinephrine on regional brain blood flow during CPR in a swine model

Cerebral blood flow (CBF) with conventional closed-chest cardiopulmonary resuscitation (CCPR) has been measured at only 2% to 11% of prearrest values. The purpose of our study was to determine whether the peripheral administration of higher doses of epinephrine than currently recommended during CCPR following a prolonged cardiac arrest improves CBF compared to CCPR using a standard dose of epinephrine. Fifteen swine were randomized to receive CCPR plus 0.02 mg/kg, 0.2 mg/kg, or 2.0 mg/kg epinephrine through a peripheral IV line following a ten-minute cardiopulmonary arrest and three minutes of CCPR. Regional CBF measurements were made by radionuclide microsphere technique during normal sinus rhythm (NSR), CCPR, and following epinephrine administration. The adjusted regional blood flows (in mL/min/100 g) following epinephrine administration for the 0.02-, 0.2-, and 2.0-mg/kg groups were, respectively, left cerebral cortex (3.3, 13.1, 11.8); right cerebral cortex (3.9, 13.8, 12.2); cerebellum (9.2, 32.0, 33.1); midbrain/pons (9.9, 32.1, 32.3); medulla (10.6, 61.5, 54.2); and cervical spinal cord (12.2, 53.8, 35.8). In this swine model, 0.2 mg/kg and 2.0 mg/kg epinephrine significantly increased regional CBF over that seen with standard doses. Because neuronal survival is dependent on flow rates of 10 to 15 mL/min/100 g, this preliminary evidence suggests that these higher doses of epinephrine may help improve neurological outcome in CCPR.