Epinephrine, but not vasopressin, improves survival rates in an adult rabbit model of asphyxia cardiac arrest

Although vasopressin has been reported to be more effective than epinephrine for cardiopulmonary resuscitation in ventricular fibrillation animal models, its efficacy in asphyxia model remains controversy. The purpose of this study was to investigate the effectiveness of vasopressin vs epinephrine on restoration of spontaneous circulation (ROSC) in a rabbit model of asphyxia cardiac arrest. Cardiac arrest was induced by clamping endotracheal tube. After 5 minutes of basic life-support cardiopulmonary resuscitation, animals who had no ROSC were randomly assigned to receive either epinephrine alone (epinephrine group; 200 μg/kg) or vasopressin alone (vasopressin group; 0.8 U/kg). The coronary perfusion pressure (CPP) was calculated as the difference between the minimal diastolic aortic and simultaneously recorded right atrial pressure. Restoration of spontaneous circulation was defined as an unassisted pulse with a systolic arterial pressure of 60 mm Hg or higher for 5 minutes or longer. We induced arrest in 62 rabbits, 15 of whom had ROSC before drug administration and were excluded from analysis. The remaining 47 rabbits were randomized to epinephrine group (n = 24) and vasopressin group (n = 23). Before and after drug administration, CPP in epinephrine group increased significantly (from −4 ± 4 to 36 ± 9 mm Hg at peak value, P = .000), whereas CPP in vasopressin group increased only slightly (from 9 ± 5 to 18 ± 6 mm Hg at peak value, P = .20). After drug administration, 13 of 24 epinephrine rabbit had ROSC, and only 2 of 23 vasopressin rabbit had ROSC (P < .01). Consequently, we conclude that epinephrine, but not vasopressin, increases survival rates in this adult rabbit asphyxia model.