title: Rapid induction of hypothermia with a small volume aortic flush during cardiac arrest in pigs.
abstract: OBJECTIVE
  The induction of deep cerebral hypothermia (15°C) via large-volume cold (4°C) saline aortic flush during cardiac arrest and resuscitation with cardiopulmonary bypass improves neurologic outcome in pigs. We hypothesized that induction of mild cerebral hypothermia (33°C) via smaller volume and resuscitation without bypass will improve survival and neurologic outcome after 15 minutes of cardiac arrest as compared with conventional resuscitation attempts.
  
  
  METHODS
  Twenty-four pigs (29-38 kg) underwent ventricular fibrillation cardiac arrest for 15 minutes. Conventional resuscitation (n=8) was compared with hypothermic (4°C, n=8) and normothermic (38.5°C, n=8) aortic flush (30 mL/kg) at the beginning of resuscitation efforts, with defibrillation attempts 2 minutes later. Outcomes after 9 days were compared.
  
  
  RESULTS
  In the hypothermic flush group, brain temperature decreased from 38.3°C±0.5°C to 33°C±0.5°C within 277±112 seconds. We observed considerably higher mean coronary perfusion pressures in the normothermic and hypothermic flush groups (hypothermic vs conventional, P=.023; normothermic vs conventional, P=.041). Three animals of each flush group, compared with none of the conventional group, achieved restoration of spontaneous circulation (P=.2); and 3 pigs of the hypothermic flush group and 2 pigs of the normothermic flush group survived to 9 days without differences in neurologic outcome.
  
  
  CONCLUSIONS
  A smaller volume, cold saline aortic flush during prolonged cardiac arrest rapidly induces mild cerebral hypothermia to 33°C and improves coronary perfusion pressure but does not result in a significant improvement in outcome as compared with conventional resuscitation attempts.
authors.affiliation: Department of Emergency Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Weihs
authors.forename: Danica
authors.initials: D
authors.lastname: Krizanac
authors.forename: Fritz
authors.initials: F
authors.lastname: Sterz
authors.forename: Gerald
authors.initials: G
authors.lastname: Hlavin
authors.forename: Andreas
authors.initials: A
authors.lastname: Janata
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Sipos
authors.forename: Michael
authors.initials: M
authors.lastname: Holzer
authors.forename: Udo M
authors.initials: UM
authors.lastname: Losert
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Behringer
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic; D001831:Body Temperature; D001921:Brain / Q000503:physiopathology; D004195:Disease Models, Animal; D005260:Female; D006323:Heart Arrest / Q000628:therapy*; D007036:Hypothermia, Induced / Q000379:methods*; D007261:Infusions, Intra-Arterial; D012121:Respiration, Artificial; D012151:Resuscitation / Q000379:methods; D012965:Sodium Chloride / Q000008:administration & dosage / Q000627:therapeutic use; D013552:Swine
chemical_list: D012965:Sodium Chloride