Influence of pentobarbital and chloral hydrate on cerebral injury after cardiopulmonary resuscitation in a rat model of cardiac arrest induced by asphyxia

Abstract

Objective To investigate the influence of choral hydrate and pentobarbital on cerebral injury after cardiopulmonary resuscitation (CPR) in a rat model of cardiac arrest induced by asphyxia.Methods One hundred and sixty male 70-95 day old SD rats weighing 300-400 g were randomly divided into 2 anesthetic groups ( n = 80 each) : chloral hydrate group (CH) and pentobarbital group (PB).Each group was further divided into 2 subgroups ( n = 40 each) : control subgroup underwent no cardiac arrest and CPR subgroup.Anesthesia was induced with intraperitoneal (IP) 5% chloral hydrate 0.35 g/kg followed by intermittent IP 5% chloral hydrate 0.1 g/kg every hour in group CH and with IP 0.35% pentobarbital 35 mg/kg followed by intermittent IP 0.35% pentobarbital 10 mg/kg every hour in group PB.Left femoral vein and right carotid artery were cunnulated for drug and fluid administration and BP monitoring.The animals were tracheostomized and mechanically ventilated.Cardiac arrest was induced by occlusion of tracheal tube and verified by disappearance of pulse wave on BP tracing and asystole/ventricular fibrillation/systolic BP 60 mm Hg lasting for more than 10 min were used as criteria for recovery of spontaneous circulation (ROSC).Eight animals were decapitated and their brains were immediately removed at 0.5,3,6,9 and 24 h (T1-5) after BOSC respectively.2% Evans blue 2 ml/kg was injected Ⅳ 15 min before each time point.Brain water content (wet weight dry weight/wet weight × 100% ) and Evan's brain content in the brain tissue were determined.Results The two groups were comparable with respect to body weight,amount of adrenaline given,duration of precordial cardiac massage and BOSC time.The brain water content and Evan's blue content in the brain tissue were significantly increased after ROSC in beth groups.The cerebral water content was significantly higher after BOSC in group CH than in group PB.There was no significant difference in Evan's blue content in the brain tissue after ROSC between the two groups.Conclusion Cardiac arrest and CPR cause cerebral edema and increase permeability of BBB.Pentobarbital shows higher degree than chloral hydrate in terms of inhibition of cerebral edema.While there is no significant difference in the influence on permeability of BBB between the two anesthetics. Key words: Pentobarhital ; Chloral hydrate; Heart arrest,induced; Cardiopulmonary resuscitation; Brain injuries