Abstract 110: Comparison of the Durations of Milder Therapeutic Hypothermia on Outcomes of Cardiopulmonary Resuscitation
Background: Current studies demonstrated that applying therapeutic hypothermia for 12 to 24 hrs following resuscitation from cardiac arrest improves the outcomes of CPR. The optimal duration of cooling, however, remains unknown. The present study investigated whether a shorter duration of therapeutic hypothermia following resuscitation would provide an equal improvement of the outcomes of CPR as the standard duration.
Hypothesis: A shorter duration of hypothermia induced rapidly and earlier following ROSC would be equally effective for improving post resuscitation myocardial and neurological function when compared with prolonged duration of hypothermia.
Methods: In 24 male S-D rats weighing between 500-550g, ventricular fibrillation was induced and untreated for 8 mins. Defibrillation was attempted after 8 mins of CPR. Resuscitated animals were then randomized into 4 groups: normothermic, hypothermic-2hrs, hypothermic-5hrs, and hypothermic-8hrs. Animals in the hypothermic groups received rapid cooling started 7 mins following ROSC and maintained at 33 ± 0.5°C for 2, 5, οr 8 hrs. Normothermic animals were maintained at 37 ± 0.2°C. Buccal microcirculatory blood flows, and ejection fraction were measured at baseline and hourly for 8 hrs following resuscitation. Neurological deficit scores and survival time were observed for up to 72 hrs.
Results: Post-resuscitation myocardial function, neurological deficit scores and 72 hr survival were significantly better in animals treated with hypothermia. However, significantly better post-resuscitation microcirculatory blood flows, ejection fraction and neurological deficit scores were observed in the hypothermic-2hrs animals (Tables 1, 2).
Conclusions: In a rat model of CPR, a shorter duration of milder hypothermia provided improvement of post-resuscitation cerebral and myocardial functions and survival compared to prolonged duration of hypothermia.
- © 2011 by American Heart Association, Inc.