Vasopressin or Epinephrine for Out-of-Hospital Cardiac Arrest

STUDY OBJECTIVE: The use of vasopressin in patients with cardiac arrest presenting with specific rhythms is controversial. We performed an evidence-based emergency medicine review of evidence comparing vasopressin to epinephrine in structured cardiac arrest protocols. METHODS: We searched MEDLINE, EMBASE, the Cochrane Library, and other databases for randomized trials or systematic reviews comparing vasopressin to epinephrine for adults with cardiac arrest and measuring survival to hospital discharge and neurologic function in survivors. We used standard criteria to appraise the quality of published trials and systematic reviews. We used the random effects model in supplementary analyses to summarize results and to test for significant differences across subgroups of patients presenting with different arrest rhythms. RESULTS: We found 3 high-quality well-reported randomized trials and 1 rigorous meta-analysis. The evidence does not confirm a consistent benefit of vasopressin over epinephrine in increasing survival or improving neurologic outcome in survivors. Subgroup analysis reveals a large difference in effect of vasopressin over epinephrine in cardiac arrest patients with asystole, compared to other arrest rhythms, coming from within-trial comparisons. The difference is not consistent across otherwise similar trials, is not statistically significant, may reflect the application of multiple unplanned subgroup analyses, and is not supported by a plausible biological hypothesis. CONCLUSION: Evidence from randomized trials does not establish a benefit of vasopressin over epinephrine in increasing survival to discharge or improving neurologic outcomes in adult patients with nontraumatic cardiac arrest.