title: Profound hypothermia is superior to ultraprofound hypothermia in improving survival in a swine model of lethal injuries.
abstract: BACKGROUND
  Rapid induction of profound hypothermia can improve survival from uncontrolled lethal hemorrhage. However, the optimal depth of hypothermia in this setting remains unknown. This experiment was designed to compare the impact of deep (15 degrees C), profound (10 degrees C), and ultraprofound (5 degrees C) hypothermia on survival and organ functions.
  
  
  METHODS
  Uncontrolled lethal hemorrhage was induced in 32 swine (80-120 lb) by creating an iliac artery and vein injury, followed 30 minutes later by laceration of the descending thoracic aorta. Hypothermia was induced rapidly (2 degrees C/min) by infusing cold organ preservation solution into the aorta through a thoracotomy. The experimental groups were (n = 8 per group): a normothermic control, and 3 hypothermic groups in which the core temperature was reduced to 15 degrees C, 10 degrees C, and 5 degrees C. Vascular injuries were repaired during 60 minutes of hypothermia. Animals were then rewarmed (0.5 degrees C/min) and resuscitated on cardiopulmonary bypass, and monitored for 6 weeks for neurologic deficits, cognitive function, and organ dysfunction.
  
  
  RESULTS
  All normothermic animals died, whereas 6-week survival rates for the 15 degrees C, 10 degrees C, and 5 degrees C groups were 62.5%, 87.5%, and 25%, respectively (P < .05: normothermic vs 15 degrees C and 10 degrees C; 10 degrees C vs 5 degrees C). The surviving animals from the 15 degrees C and 10 degrees C groups were neurologically intact, displayed normal learning capacity, and had no long-term organ dysfunction. The survivors from the 5 degrees C group displayed slower recovery and impaired cognitive functions.
  
  
  CONCLUSIONS
  In a model of lethal injuries, rapid induction of profound hypothermia can prevent death. The depth of hypothermia influences survival, with a better outcome associated with a core temperature of 10 degrees C compared with 5 degrees C.
authors.affiliation: Trauma Research and Readiness Institute for Surgery, Uniformed Services University of the Health Sciences, Bethesda, USA.
authors.forename: Hasan B
authors.initials: HB
authors.lastname: Alam
authors.forename: Zheng
authors.initials: Z
authors.lastname: Chen
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Li
authors.forename: George
authors.initials: G
authors.lastname: Velmahos
authors.forename: Marc
authors.initials: M
authors.lastname: DeMoya
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Keller
authors.forename: Kevin
authors.initials: K
authors.lastname: Toruno
authors.forename: Tina
authors.initials: T
authors.lastname: Mehrani
authors.forename: Peter
authors.initials: P
authors.lastname: Rhee
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Spaniolas
mesh_terms: D000818:Animals; D001831:Body Temperature; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000009:adverse effects / Q000379:methods* / Q000523:psychology; D003071:Cognition / Q000502:physiology; D004195:Disease Models, Animal; D005260:Female; D012771:Shock, Hemorrhagic / Q000473:pathology / Q000523:psychology / Q000628:therapy*; D013552:Swine; D014950:Wounds, Penetrating / Q000473:pathology / Q000523:psychology / Q000628:therapy*