Field-induced therapeutic hypothermia for neuroprotection after out-of hospital cardiac arrest: a systematic review of the literature.

BACKGROUND Emergency Medical Services (EMS) has started to embrace the early use of therapeutic hypothermia as standard treatment to improve neurological recovery in out-of hospital cardiac arrest (OHCA) survivors. OBJECTIVE We conducted a systematic review to provide an overall description of the current literature on the use of therapeutic hypothermia in OHCA and to identify possible gaps in the literature. METHODS Comprehensive searches of MEDLINE, PubMed, CINAHL, and ISI Web of Science from 1950 to March 2009, and EMBASE from 1988 to March 2009 were performed. Bibliographies of selected articles were hand searched. Two reviewers independently selected studies on the basis of three inclusion criteria. Two additional independent reviewers assessed selected studies for quality. RESULTS Of more than 800 screened citations, a total of 11 published studies were included in the systematic review. Three studies were conducted in the United States, three in Finland, and one each in Australia, France, Germany, Austria, and Norway. Four of the studies were pilot clinical trials that provided prehospital mild therapeutic hypothermia during active cardiopulmonary resuscitation. The remaining seven studies performed cooling after return of spontaneous circulation. Significant differences in research methodology and outcome measures were noted. Eight studies scored poor for quality. CONCLUSIONS The use of mild therapeutic hypothermia is gaining acceptance within the EMS community. It seems that hypothermia can be efficiently induced in the prehospital environment. There is a need for more research in this area to understand the effectiveness and timing of early therapeutic hypothermia in the prehospital environment.