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Vasopressin for Asystolic Cardiac Arrest?

It might be premature to replace epinephrine for this indication.

Survival rates after CPR for out-of-hospital cardiac arrest remain disappointingly low. Preliminary studies have suggested that vasopressin, a nonadrenergic vasoactive drug (also known as antidiuretic hormone), might be superior to epinephrine, which has been a cornerstone of cardiac-arrest treatment.

In a partially industry-sponsored, multicenter, double-blind, randomized trial from Europe, researchers compared the effects of injecting 2 ampules of either 1-mg epinephrine or 40-IU vasopressin in 1186 adults (mean age, 66; 70% male) with out-of-hospital cardiac arrest. Study drugs were readministered if restoration of spontaneous circulation (ROSC) was not achieved within 3 minutes; if still no ROSC, an additional epinephrine injection was given at physician discretion. All subjects presented with ventricular fibrillation, pulseless electrical activity, or asystole requiring CPR. About 78% of the arrests were witnessed. The average time from arrest to administration of basic life support was 8 minutes.

In both groups, 9.9% of patients survived to hospital discharge, with a slight, nonsignificant advantage in ROSC for epinephrine (28.0%) over vasopressin (24.6%). Although epinephrine had a slight, nonsignificant advantage over vasopressin in survival to discharge in the subgroups of patients who presented with ventricular fibrillation (19.2% vs. 17.8%) or pulseless electrical activity (8.6% vs. 5.9%), epinephrine fared worse for this outcome among patients who presented with asystole (1.5% survival with epinephrine vs. 4.7% with vasopressin, P=0.04; odds ratio, 0.3; 95% CI, 0.1-1.0). Within the asystole subgroup, ROSC rates were similar with the 2 drugs (16.5% and 16.0%, respectively). Within the subgroup of patients who received supplementary epinephrine after the study drug had failed twice to achieve ROSC, those with asystole had a significantly higher rate of survival to hospital discharge with vasopressin (3.8%) than with epinephrine (0%).

Comment: The authors write that their findings support using vasopressin for asystolic cardiac arrest. The editorialist goes even further and calls for immediate revision of ACC/AHA guidelines. However, the data are short of definitive evidence favoring vasopressin and should be viewed cautiously: The advantage of vasopressin within the entire asystolic subgroup was borderline, and the outcomes for patients who received supplementary epinephrine were not prespecified as an endpoint. What the study does prove is that the overall prognosis for patients with out-of-hospital arrest remains grim.

— Harlan M. Krumholz, MD, SM

Published in Journal Watch Cardiology February 20, 2004

Citation(s):

Wenzel V et al. for the European Resuscitation Council Vasopressor during Cardiopulmonary Resuscitation Study Group. A comparison of vasopressin and epinephrine for out-of-hospital cardiopulmonary resuscitation. N Engl J Med 2004 Jan 8; 350:105-13.

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• Medline abstract (Free)

McIntyre KM. Vasopressin in asystolic cardiac arrest. N Engl J Med 2004 Jan 8; 350:179-81.

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• Medline abstract (Free)