and epinephrine used together versus epinephine alone in out-ofhospital cardiac arrest (CA). Methods We searched MEDLINE for randomised trials comparing the efficacy of vasopressin and epinephrine versus epinephrine alone in adults who experienced out-of-hospital CA. The primary outcome was the return of spontaneous circulation (ROSC) and the survival rate on admission and discharge. We also analysed ROSC in subgroups of patients presenting with different arrest rhythms. Results In total, 206

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... ticles were enrolled and five studies were included. No differences were found between these groups (vasopressin and epinephrine group vs. epinephrine alone group), except for the survival rate at 24 h (OR 2.99, 95% CI 1.43, 6.28). No evidence supports the conclusion that vasopressin combined with epinephrine is better than epinephrine alone for ROSC, even amongst subgroups of patients. Conclusion This systematic review of the efficacy of vasopressin and epinephrine found that its combined use is better for 24 h survival rate but only in one study which included 122 patients. Further investigation will be needed to support the -use of this combination for out-of-hospital CA management.