Sex differences in cardiac injury after severe haemorrhage and ventricular fibrillation in pigs.

Abstract

Experimental studies have shown sex differences in haemodynamic response and outcome after trauma and haemorrhagic shock. We recently reported that female sex protects against cerebral injury after exsanguination cardiac arrest (CA), independent of sexual effects of hormones. The current study examines if female sex is also cardioprotective. In this study 21 sexually immature piglets (12 males and 9 females) were subjected to 5 min of haemorrhagic shock followed by 2 min of ventricular fibrillation and 8 min of cardiopulmonary resuscitation (CPR). Volume resuscitation was started during CPR with intravenous administration of 3 ml kg(-1) hypertonic saline-dextran (HSD) solution for 20 min. Sexually immature animals were used to differentiate innate sex differences from the effects of sexual hormones. Sex differences in haemodynamics, myocardial injury (troponin I), and short-term survival (3-h) were evaluated. After resuscitation female animals had a higher blood pressure, lower heart rate, lower troponin I concentrations, and higher survival rate (100% and 63% in 3 h) despite comparable sex hormone levels. After resuscitation from haemorrhage and circulatory arrest, haemodynamic parameters are better preserved and myocardial injury is smaller in female piglets. This difference in outcome is independent of sexual hormones.