Increased cortical cerebral blood flow by continuous infusion of adrenaline (epinephrine) during experimental cardiopulmonary resuscitation.

OBJECTIVE: To study the effects of continuously administered adrenaline (epinephrine), compared to bolus doses, on the dynamics of cortical cerebral blood flow during experimental cardiopulmonary resuscitation (CPR), and after restoration of spontaneous circulation (ROSC).
METHODS: Ventricular fibrillation was induced in 24 anaesthetised pigs. After a 5-min non-intervention interval, closed-chest CPR was started. The animals were randomised into two groups. One group received three boluses of adrenaline (20 microg/kg) at 3-min intervals. The other group received an initial bolus of adrenaline (20 microg/kg) followed by an infusion of adrenaline (10 microg/kg x min). After 9 min of CPR, defibrillation was attempted, and if spontaneous circulation was achieved the adrenaline infusion was stopped. Cortical cerebral blood flow was measured continuously using Laser-Doppler flowmetry. Jugular bulb oxygen saturation was measured to reflect global cerebral oxygenation. Repeated measurements of 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) in jugular bulb plasma were performed to evaluate cerebral oxidative injury.
RESULTS: During CPR mean cortical cerebral blood flow was significantly higher (P=0.009) with a continuous adrenaline infusion than with repeated bolus doses. Following ROSC there was no significant difference in cortical cerebral blood flow between the two study groups. No differences in coronary perfusion pressure, rate of ROSC, jugular bulb oxygen saturation or 8-iso-PGF(2alpha) were seen between the study groups.
CONCLUSIONS: Continuous infusion of adrenaline (10 microg/kg x min) generated a more sustained increase in cortical cerebral blood flow during CPR as compared to intermittent bolus doses (20 microg/kg every third minute). Thus, continuous infusion might be a more appropriate way to administer adrenaline as compared to bolus doses during CPR.