Vasopressin alone or with epinephrine may be superior to epinephrine in asystolic out-of-hospital cardiac arrest: an observational study

Background

In patients undergoing cardiopulmonary resuscitation, circulating endogenous vasopressin concentrations were significantly higher in successfully resuscitated patients than in patients who died. Clinical data considering vasopressin to be an equivalent option to epinephrine in cardiopulmonary resuscitation (CPR) are limited. The studies of out-of-hospital cardiac arrest (OHCA) confirm an increasing part of asystole as the initial rhythm. The hypothesis of this study was that vasopressin improves the rate of return of spontaneous circulation (ROSC) and the survival rate in asystolic OHCA, when used early in the resuscitation effort.

Methods

This was a prospective cohort study, with a historic group compared trial set in an urban emergency medical services system, serving a population of 200,000. All nonpregnant, normothermic adults (>18 years) suffering nontraumatic OHCA with asystole were eligible. We compared two treatment groups of resuscitated patients with OHCA. In the epinephrine group (EPI) patients received epinephrine 1 mg i.v. every 3 minutes only. In the vasopressin group (VASO) patients received arginine vasopressin 40 IU i.v. only or followed by epinephrine 1 mg every 3 minutes during CPR.

Statistics

Exact Fisher test, Wilcoxon rank-sum test, and analysis of independent predictors with multivariate logistic regression were used; P < 0.05.

Results

The investigators enrolled 227 consecutive patients: in the EPI group 183 patients (years 2001–2003) and in the VASO group 44 patients (year 2004). Baseline (demographic and clinical) characteristics were similar for the two groups. Comparing the EPI and VASO groups, any ROSC was achieved in 81/183 (44%) and 34/44 (77%), P = 0.04; ROSC with admission in 61/183 (33%) and 27/44 (61%), P = 0.03; 24-hour survival in 44/183 (24%) and 23/44 (52%), P = 0.01; and discharge from hospital in 17/183 (9%) and 10/44 (23%), P = 0.04. Vasopressin was an independent predictor of ROSC with admission with an odds ratio of 2.4 (95% CI = 1.24–4.98).

Conclusion

Vasopressin was superior to epinephrine in patients with asystole (better ROSC with admission, 24-hour survival and discharge from hospital). Vasopressin followed by epinephrine was more effective than epinephrine alone in the treatment of refractory cardiac arrest.