Topical head cooling during rewarming after experimental hypothermic circulatory arrest

Background The aim of this study was to evaluate the potential neuroprotective effect of topical head cooling during the first 2 postoperative hours after experimental hypothermic circulatory arrest. Methods Twenty pigs underwent a 75-minute period of hypothermic circulatory arrest and were randomly assigned to rewarming to 37°C or to undergo topical cooling of the head for 2 hours from the start of rewarming followed by a period of external rewarming to 37°C. Results The 7-day survival rate was 70% in the control group and 60% in the topical head cooling group. Despite brain tissue oxygenation, intracranial pressures, mixed oxygen venous saturation, oxygen consumption, and extraction tended to be favorable in the topical head cooling group as a clear effect of mild hypothermia. The latter group had significantly higher postoperative brain lactate and pyruvate ratios, and lactate and glucose ratios. Furthermore, the topical head cooling group had worse fluid balance throughout the postoperative period. Brain histopathologic scores were comparable with the study groups, but among 7-days survivors these scores tended to be worse in the topical head cooling group. Conclusions Topical cooling of the head during the first 2 postoperative hours after experimental hypothermic circulatory arrest does not appear to provide any neuroprotective effect.