Comparison of epinephrine and vasopressin in a pediatric porcine model of asphyxial cardiac arrest

Objective: This study was designed to compare the effects of vasopressin vs. epinephrine vs. the combination of epinephrine with vasopressin on vital organ blood flow and return of spontaneous circulation in a pediatric porcine model of asphyxial arrest. Design: Prospective, randomized laboratory investigation using an established porcine model for measurement of hemodynamic variables, organ blood flow, blood gases, and return of spontaneous circulation. Setting: University hospital laboratory. Subjects: Eighteen piglets weighing 8-11 kg. Interventions: Asphyxial cardiac arrest was induced by clamping the endotracheal tube. After 8 mins of cardiac arrest and 8 mins of cardiopulmonary resuscitation, a bolus dose of either 0.8 units/kg vasopressin (n = 6), 200 μg/kg epinephrine (n = 6), or a combination of 45 μg/kg epinephrine with 0.8 units/kg vesopressin (n = 6) was administered in a randomized manner. Defibrillation was attempted 6 mins after drug administration. Measurements and Main Results: Mean ± SEM coronary perfusion pressure, before and 2 mins after drug administration, was 13 ± 2 and 23 ± 6 mm Hg in the vasopressin group; 14 ± 2 and 31 ± 4 mm Hg in the epinephrine group; and 13 ± 1 and 33 ± 6 mm Hg in the epinephrine-vasopressin group, respectively (p = NS). At the same time points, mean ± SEM left ventricular myocardial blood flow was 44 ± 31 and 44 ± 25 mL · min^-1 · 100 g^-1 in the vasopressin group; 30 ± 18 and 233 ± 61 mL · min^-1 · 100 g^-1 in the epinephrine group; and 36 ± 10 and 142 ± 57 mL · min^-1 · 100 g^-1 in the epinephrine-vasopressin group (p < .01 epinephrine vs. vasopressin; p < .02 epinephrine-vasopressin vs. vasopressin). Total cerebral blood flow trended toward higher values after epinephrine-vasopressin (60 ± 19 mL · min^-1 · 100 g^-1) than after vasopressin (36 ± 17 mL · min^-1 · 100 g^-1) or epinephrine alone (31 ± 7 mL · min^-1 · 100 g^-1; p = .07, respectively). One of six vasopressin, six of six epinephrine, and four of six epinephrine-vasopressin-treated animals had return of spontaneous circulation (p < .01, vasopressin vs. epinephrine). Conclusions: Administration of epinephrine, either alone or in combination with vasopressin, significantly improved left ventricular myocardial blood flow during cardiopulmonary resuscitation. Return of spontaneous circulation was significantly more likely in epinephrine-treated pigs than in animals resuscitated with vasopressin alone.