title: Extracorporeal venovenous cooling for induction of mild hypothermia in human-sized swine.
abstract: OBJECTIVE
  Several cooling methods have been investigated for inducing mild hypothermia (33-36 degrees C) after cardiac arrest, brain trauma, or stroke. To achieve its best effect, therapeutic hypothermia has to be applied very early after the ischemic insult; otherwise, the beneficial effect would be diminished or even abrogated. The aim of this study was to investigate the effectiveness and safety of extracorporeal venovenous cooling as compared with endovascular cooling.
  
  
  METHODS
  Swine were cooled in a randomized crossover design from 38 degrees C to 33 degrees C brain temperature, either with extracorporeal venovenous cooling or with endovascular cooling.
  
  
  METHODS
  Laboratory investigation.
  
  
  METHODS
  Six swine of human size (85 to 101 kg).
  
  
  METHODS
  Swine were randomly cooled with the first device, and after achieving the target brain temperature, re-warmed via the same technique and with heating lamps to baseline temperature. Then the other catheter was inserted and cooling was performed with the second device.
  
  
  METHODS
  Brain, pulmonary artery and tympanic temperature, blood pressure, and heart rate were recorded continuously. Laboratory samples, including free hemoglobin, were taken at predefined temperature points during cooling. Comparisons between and within (baseline vs. 33 degrees C) the treatment groups were performed with the paired Student's t-test.
  
  
  RESULTS
  The time needed to reduce brain temperature from 38.0 degrees C to 33.0 degrees C was 41 +/- 17 mins with venovenous cooling and 126 +/- 37 mins with endovascular cooling (p = .001). Heart rate and mean arterial pressure decreased moderately during cooling and were significantly lower at 33 degrees C than at baseline in both groups, without differences between groups. None of the swine developed significant hemolysis, arrhythmias, or bleeding.
  
  
  CONCLUSIONS
  Extracorporeal venovenous cooling was an effective and safe method to rapidly induce therapeutic mild hypothermia in human-sized swine. It seems to be promising for further application and investigation in patients.
authors.affiliation: Department of Emergency Medicine, Medical University Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Holzer
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Behringer
authors.forename: Andreas
authors.initials: A
authors.lastname: Janata
authors.forename: Keywan
authors.initials: K
authors.lastname: Bayegan
authors.forename: Heinrich
authors.initials: H
authors.lastname: Schima
authors.forename: Zeno
authors.initials: Z
authors.lastname: Deckert
authors.forename: Udo
authors.initials: U
authors.lastname: Losert
authors.forename: Anton N
authors.initials: AN
authors.lastname: Laggner
authors.forename: Fritz
authors.initials: F
authors.lastname: Sterz
mesh_terms: D000818:Animals; D001831:Body Temperature; D001921:Brain / Q000502:physiology; D002545:Brain Ischemia / Q000628:therapy*; D002405:Catheterization, Central Venous / Q000379:methods; D018592:Cross-Over Studies; D005112:Extracorporeal Circulation; D005260:Female; D007036:Hypothermia, Induced / Q000379:methods*; D011897:Random Allocation; D018709:Statistics, Nonparametric; D013552:Swine; D013997:Time Factors