Developing a vasopressor combination in a pig model of adult asphyxial cardiac arrest

Background - The purpose of this study was to investigate the effects of vasopressin versus epinephrine, and both drugs combined, in a porcine model of simulated adult asphyxial cardiac arrest. Methods and Results - At ≈7 minutes after the endotracheal tube had been clamped, cardiac arrest was present in 24 pigs and remained untreated for another 8 minutes. After 4 minutes of basic life support cardiopulmonary resuscitation, pigs were randomly assigned to receive, every 5 minutes, either epinephrine (45, 200, or 200 μg/kg; n=6); vasopressin (0.4, 0.8, or 0.8 U/kg; n=6); or epinephrine combined with vasopressin (high-dose epinephrine/vasopressin combination, μg/kg and U/kg: 45/0.4, 200/0.8, or 200/0.8; n=6; optimal-dose epinephrine/vasopressin combination, 45/0.4, 45/0.8, or 45/0.8; n=6). Mean±SEM coronary perfusion pressure was significantly (P<0.05) higher 90 seconds after high- or optimal-dose epinephrine/vasopressin combinations versus vasopressin alone and versus epinephrine alone (37±10 versus 25±7 versus 19±8 versus 6±3 mm Hg; 42±6 versus 40±5 versus 21±5 versus 14±6 mm Hg; and 39±6 versus 37±4 versus 9±3 versus 12±4 mm Hg, respectively). Six of 6 high-dose, 6 of 6 optimal-dose vasopressin/epinephrine combination, 0 of 6 vasopressin, and 1 of 6 epinephrine pigs had return of spontaneous circulation (P<0.05). Conclusions - Epinephrine combined with vasopressin, but not epinephrine or vasopressin alone, maintained elevated coronary perfusion pressure during cardiopulmonary resuscitation and resulted in significantly higher survival rates in this adult porcine asphyxial model.