The effect of mild hypothermia and induced hypertension on long term survival rate and neurological outcome after asphyxial cardiac arrest in rats

Abstract

Study objective: we studied the long-term effect of a combined treatment with resuscitative mild hypothermia and induced hypertension on survival rate and neurological outcome after asphyxial cardiac arrest (CA) in rats. Methods: 36 male Wistar rats, were randomised into three groups: Group I ( n=10): anaesthetised with halothane and N 2O/O 2 (70/30%) had vessel cannulation but no asphyxial CA; mechanical ventilation was continued to 1 h. Group II ( n=13): under the same anaesthetic conditions and vessel cannulation, was subjected to asphyxial CA of 8 min, reversed by brief external heart massage and followed by mechanical ventilation to 1 h post restoration of spontaneous circulation (ROSC). Group III ( n=13): received the same insult and resuscitation as described in group II, but in contrast to the previous group, a combination treatment of hypothermia (34°C) and induced hypertension was started immediately after ROSC and maintained for 60 min ROSC. Survival rate and neurological deficit (ND) scores were determined before arrest, at 2 and 24 h, and each 24-h up to 4 weeks after ROSC. Results: Baseline variables were the same in the three groups. Comparison of the asphyxial CA groups (groups II and III), showed an increased, although not statistically significant, survival rate at 72 h after ROSC in group III, and it became highly significant at 4 weeks after ROSC. The ND scores were the same in both asphyxial CA groups (groups II and III). Conclusions: Resuscitative mild hypothermia and induced hypertension after asphyxial CA in rats is associated with a better survival rate. This beneficial effect persisted for 4 weeks after ROSC.