Vasopressin is recommended for cardiac arrest according to current American Heart Association guidelines. In a pre-released article in Resuscitation, Mentzelopoulos et al performed a meta-analysis to determine whether the cumulative evidence supports or refutes outcomes benefits for vasopressin when used for adult cardiac arrest.

After a limited search involving PubMed, EMBASE, and the Cochrane registry, six randomized controlled trials were identified. These studies reported the type of arrest (in-hospital versus out-of-hospital), a comparison group (placebo or another drug) and survival. Primary outcomes were return of spontaneous circulation (ROSC), 30-day survival and functional neurological status as defined by a Glasgow-Pittsburgh Cerebral Performance Category (CPC) score of 1 or 2. The authors did not report so-called gray literature (i.e., research not found through conventional publishing channels), abstracts from recent conferences, references from included studies, or other bibliographic databases. Moreover, formal assessments for risk of bias were not described in the methods section of the paper. Validity criteria were unclear, but the authors reported assessing methodological quality in an eSupplement that was not available at the time of this appraisal.

Despite moderate to high degrees of heterogeneity (I2 46-71%), the authors completed a meta-analysis. Neither ROSC, long-term survival or favorable neurological outcomes were statistically significantly associated with the use of vasopressin. In a subgroup analysis of studies reporting long-term survival after asystole and administration of the drug within 20 minutes of arrest, vasopressin was associated with higher odds of survival (odds ratio [OR] 2.84; 95% confidence interval [CI] 1.19, 6.79; p=0.02). ROSC was also higher in two studies reporting the use of vasopressin in asystole when given within 20 minutes of arrest (OR 1.70; 95% CI 1.17, 2.47; p=0.005).

To date, none of the four core advanced cardiac life support drugs (lidocaine, amiodarone, epinephrine, vasopressin) have been shown to affect long-term survival, even though ROSC rates may be increased in both human and animal models. Although these drugs have not been shown to advance long-term outcomes, most experts believe there is little harm and potential short-term benefits. Notwithstanding the methodological limitations of this meta-analysis, the results support a possible role for vasopressin in asystole when the drug is given promptly as a one-time substitution for epinephrine. Whether there is enough equipoise to pursue this finding with additional placebo-controlled studies remains to be seen.

Concise Critical Appraisal is a regular feature authored by SCCM member Samuel M. Galvagno Jr., DO. Each installment highlights journal articles most relevant to the critical care practitioner.