Adverse effects of high-dose epinephrine on cerebral blood flow during experimental cardiopulmonary resuscitation

Objective: To study the effects of high-dose epinephrine, compared with standard-dose epinephrine, on the dynamics of superficial cortical cerebral blood flow as well as global cerebral oxygenation during experimental cardiopulmonary resuscitation, We hypothesized that high-dose epinephrine might be unable to improve cerebral blood flow during cardiopulmonary resuscitation as compared with standard-dose epinephrine. Design: Randomized controlled study. Setting: University hospital research laboratory, Subjects: A total of 20 male anesthetized piglets. Interventions: Ventricular fibrillation was induced. A nonintervention interval of 8 mins was followed by open-chest cardiopulmonary resuscitation, The animals were randomized to receive repeated bolus injections of either 20 mu g/kg (standard-dose group, n = 10) or 200 mu g/kg (high-dose group, n = 10) of epinephrine. Measurements and Main Results: Focal cortical cerebral blood how was measured continuously by using laser Doppler flowmetry, The duration of blood flow increase was significantly shorter in the high-dose group after the second dose of epinephrine, In the high-dose group there was also a consistent tendency for lower peak levels and shorter duration of flow increase in response to repeated bolus doses of epinephrine. Cerebral oxygen extraction ratio was significantly lower in the high-dose group after administration of epinephrine, Conclusions: Repeated bolus doses of epinephrine 200 mu g/kg, as compared with 20 mu g/kg, do not improve superficial cortical cerebral blood flow during experimental open-chest cardiopulmonary resuscitation. High-dose epinephrine appears to induce vasoconstriction of cortical cerebral blood vessels resulting in redistribution of blood flow from superficial cortex. This might be one explanation for the failure of high-dose epinephrine to improve overall outcome in clinical trials.