A Novel Method for Inducing Therapeutic Hypothermia in a Swine Model of Blast-Induced Traumatic Brain Injury with Associated Hemorrhagic Shock

The purpose of this study was to determine the effect of rapidly induced hypothermia on neurological outcomes following fluid percussion injury in swine. A second objective was to test the safety and efficacy of inducing hypothermia through augmented heat extraction from the lungs using heliox and perfluorocarbon mist ventilation. The hypothermia device was built and bench tested. Brain temperatures in all hypothermic animals reached target (32-33 C) within 60 minutes. We standardized the anatomical location and fluid force necessary to create consistent severe brain injury in pigs. Seven of the eight hypothermic and four of the eight normothermic animals survived to the end of the five-day study. Hypothermia effectively prevented the gradual rise in intracranial pressure. Neurological and behavioral scores were better in the surviving normothermic animals on day #3; however these differences disappeared by day #5. The results of serum biomarkers for brain injury and histopathological scores are being processed. The study was extended by six months due to the additional safety and feasibility requirements placed by Mayo IACUC and the inclusion of serum biomarkers into the protocol. If additional funding becomes available, the investigators will add a third arm to the study consisting of blast injury plus hemorrhagic shock.
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