Early achievement of mild therapeutic hypothermia and the neurologic outcome after cardiac arrest.

BACKGROUND: Mild therapeutic hypothermia (MTH) achieved by endovascular cooling has emerged as a new treatment strategy to reduce hypoxic brain injury after cardiac arrest (CA). It remains to be established how the time interval between CA and MTH impacts the neurologic outcome. We hypothesized that a more rapid achievement of MTH (time to target temperature [TTT], time to coldest temperature [TCT]) improves the outcome after CA.
METHODS: Forty-nine consecutive patients successfully resuscitated from CA were enrolled. MTH with a body core temperature between 32.0 and 34.0 degrees C (target temperature: 33.0 degrees C) over 24 h was achieved using a closed-loop endovascular system. Based on the neurologic outcome at discharge, the patient group was dichotomized into good (no/mild cerebral disability) and poor (severe disability, coma/vegetative state, brain death) outcomes. Serum neurone specific enolase (NSE) as biochemical marker of brain damage was sampled at 24, 48, and 72 h after CA.
RESULTS: Twenty-eight patients were discharged with a good outcome. Multivariate stepwise regression showed TTT (odds ratio for every h TTT: 0.69 [95% confidence interval: 0.51-0.98]) or, if entered into the model, TCT (odds ratio for every h TCT: 0.72 [95% confidence interval: 0.56-0.94]) to be independent predictors for good outcome. Further independent determinants were age, BMI, asystole as presenting rhythm, and thrombolysis during resuscitation. However, TCT was the only variable to correlate with maximum NSE values after CA (r=0.32, P<0.05).
CONCLUSIONS: Early achievement of MTH by endovascular cooling appears to reduce hypoxic brain injury and to favour a good neurologic outcome after CA.