Mild resuscitative hypothermia and outcome after cardiopulmonary resuscitation

Recovery without residual neurological damage after cardiac arrest with global cerebral ischemia is still a rare event. Severe impairment of bodily or cognitive functions is often the result. The individual, emotional, and social aspects of brain damage and rehabilitation are seldom taken into account. Efforts to improve the prevention of brain damage immediately after successful resuscitation of patients are missing. The efficacy of hypothermia in preserving neurologic function when instituted before and during certain no-flow cardiovascular states has been well documented both clinically and experimentally since the 1950s. Most studies have used moderate (28-33 degrees C) to deep (20-28 degrees C) hypothermia to demonstrate these protective effects. Considering the use of hypothermia for preservation and resuscitation, the lack of controlled outcome trials, the long period of time required to reach therapeutic hypothermia, and the incidence of rewarming complications such as infection, arrhythmia, and coagulopathy have made it difficult to apply these methods to emergency situations such as cardiac arrest. Recent experimental evidence in dogs has shown that hypothermia induced after cardiac arrest does indeed mitigate the effects of the postresuscitation syndrome and improves neurologic function and reduces histologic brain damage. More importantly, such benefits can be demonstrated with mild (34-36 degrees C) hypothermia, thus minimizing complications and requiring less time for induction of hypothermia. Ice water nasal lavage, direct carotid infusion of cold fluids, use of a cooling helmet, and peritoneal cooling are promising techniques for clinical cerebral cooling. External auditory canal temperature (e.g., tympanic membrane temperature changes) could provide an approximation to brain temperatures. For accurate temperature monitoring, however, a central pulmonary artery thermistor probe should be inserted. Temperature monitoring is needed to avoid temperature < 30 degrees C. Mild hypothermia may prove to be an important and secure component for cerebral preservation and resuscitation during and after global ischemia; it may also prove to be a useful method of cerebral resuscitation after global ischemic states, thereby promoting the prevention of neuromental diseases.