Repeated administration of vasopressin but not epinephrine maintains coronary perfusion pressure after early and late administration during prolongedcardiopulmonary resuscitation in pigs

Background-It is unknown whether repeated dosages of vasopressin or epineph rine given early or late during basic life support cardiopulmonary resuscit ation (CPR) may be able to increase coronary perfusion pressure above a thr eshold between 20 and 30 mm Hg that renders defibrillation successful. Methods and Results-After 4 minutes of cardiac arrest, followed by 3 minute s of basic life support CPR, 12 animals were randomly assigned to receive, every 5 minutes, either vasopressin (early vasopressin: 0.4, 0.4, and 0.8 U /kg, respectively; n=6) or epinephrine (early epinephrine: 45, 45, and 200 mu g/kg, respectively; n=6). Another 12 animals were randomly allocated aft er 4 minutes of cardiac arrest, followed by 8 minutes of basic life support CPR, to receive, every 5 minutes, either vasopressin (late vasopressin: 0. 4 and 0.8 U/kg, respectively; n=6), or epinephrine (late epinephrine: 45 an d 200 mu g/kg, respectively; n=6). Defibrillation was attempted after 22 mi nutes of cardiac arrest. Mean+/-SEM coronary perfusion pressure was signifi cantly higher 90 seconds after early vasopressin compared with early epinep hrine (50+/-4 versus 34+/-3 mm Hg, P<0.02; 42+/-5 versus 15+/-3 mm Hg, P<0. 0008; and 37+/-5 versus 11+/-3 mm Hg, P<0.002, respectively). Mean+/-SEM co ronary perfusion pressure was significantly higher 90 seconds after late va sopressin compared with late epinephrine (40+/-3 versus 22+/-4 mmHg, P<0.00 4, and 32+/-4 versus 15+/-4 mm Hg, P<0.01, respectively). All vasopressin a nimals survived 60 minutes, whereas no epinephrine pig had return of sponta neous circulation (P<0.05). Conclusions-Repeated administration of vasopressin but only the first epine phrine dose given early and late during basic life support CPR maintained c oronary perfusion pressure above the threshold that is needed for successfu l defibrillation.