Female sex is not associated with improved rates of ROSC or short term survival following prolonged porcine ventricular fibrillation.

Abstract

There may be a survival benefit in female patients experiencing cardiac arrest, which could affect the interpretation of in vivo animal studies. We hypothesized that sex predicts return of spontaneous circulation (ROSC) and short-term survival (SURV) in porcine studies of prolonged ventricular fibrillation (VF). Retrospective analysis of eight comparable experiments performed in our lab using mixed-breed domestic swine of either sex. All experiments included prolonged untreated VF, CPR, defibrillation, and drugs. We defined ROSC as systolic blood pressure ≥80 mm Hg for ≥1 min. Short-term survival was defined 20 or 60 min, depending on protocol. Categorical variables were compared with chi-square test and Fisher's exact test. Continuous variables were compared with two-sample t-test and one-way ANOVA. Multiple logistic regression determined predictors of ROSC and SURV, utilizing cluster analysis by experimental protocol. Candidate variables were sex, weight, anesthesia duration, VF duration, and CPR ratio. Of 263 swine analyzed (53.2% male), 58.6% of males and 68.3% of females had ROSC (p=0.10), whereas 50.0% of males and 61.0% of females experienced SURV (p=0.07). Of 263 swine analyzed (53.2% male), 58.6% of males and 68.3% of females had ROSC (p=0.10), whereas 50.0% of males and 61.0% of females experienced SURV (p=0.07). Neither sex nor any identified candidate variable predicted ROSC or SURV. Both models had acceptable fit with Hosmer-Lemeshow values of 0.35 and 0.31, respectively. Sex predicts neither ROSC nor SURV in a swine model of prolonged VF.