Differences in the pharmacodynamics of epinephrine and vasopressin during and after experimental cardiopulmonary resuscitation

Vasopressin has been investigated as a possible alternative to epinephrine during cardiopulmonary resuscitation (CPR). We tested the hypothesis that vasopressin, in comparison with epinephrine, would improve cerebral blood flow and metabolism during CPR as well as after restoration of spontaneous circulation (ROSC). A total of 22 anaesthetised piglets were subjected to 5 min of ventricular fibrillation followed by 8 min of closed-chest CPR. The piglets were randomly allocated to receive repeated boluses of either 45 mug/kg epinephrine or 0.4 U/g vasopressin IV. Haemodynamic parameters, cerebral cortical blood flow and cerebral tissue pH and PCO2 were continuously monitored during CPR and up to 4 h after ROSC. Cerebral oxygen extraction ratio was calculated. Cerebral cortical blood Row increased transiently after each bolus of epinephrine, while only the first bolus of vasopressin resulted in a sustained increase. The peak in cerebral cortical blood Row was reached similar to 30 s later with vasopressin. During the initial 5 min following ROSC, cerebral cortical blood flow was greater in the vasopressin group. In conclusion, there is a difference between epinephrine and vasopressin in the time from injection to maximal clinical response and the duration of their effect, bur their overall effects on blood pressures and cerebral perfusion do not differ significantly during CPR. In contrast, vasopressin results in a greater cerebral cortical blood how during a transient period after ROSC. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.