Synergistic effects of vasopressin plus epinephrine during cardiopulmonary resuscitation

Both epinephrine (Epi) and vasopressin (VP) increase coronary perfusion pressure (CPP) when administered during cardiac arrest. Given their different mechanisms of action we tested the hypothesis that during cardiopulmonary resuscitation (CPR) a combination of VP plus Epi would be superior to either agent alone. Epi (40 μg/kg), VP (0.3 U/kg) and the combination of both agents were assessed in a porcine model of ventricular fibrillation (VF). Maximum CPP (diastolic aortic-right atrial pressures) during CPR was similar among the groups but the time course of action was different in each group: with Epi ± VP the increase in CPP was significantly more rapid than with VP alone whereas the CPP remained significantly higher for a longer periods of time with VP or VP + Epi versus Epi alone. Left ventricular blood flow (ml/min per g) determined during CPR two min after drug administration was similar between groups: Epi 1.06 ± 0.16; VP 0.82 ± 0.26; Epi + VP 0.83 ± 0.14 (P = N.S.). Post drug administration, 2 min, cerebral blood flow (ml/min per g) in the VP group (0.76 ± 0.15) was more than two times higher compared with Epi alone (Epi: 0.30 ± 0.08, P < 0.01 versus VP) and Epi plus VP (Epi + VP: 0.23 ± 0.03, P < 0.01 versus VP). We conclude that combination of VP + Epi during cardiac arrest results in a more rapid rise in CPP when compared with VP alone and a more sustained elevation in CPP than observed with Epi alone. Thus, the synergistic effects of these two potent vasopressor agents may be of benefit during CPR.