title: The impact of deep and moderate body temperatures on end-organ function during hypothermic circulatory arrest.
abstract: OBJECTIVE
  Hypothermic circulatory arrest (HCA) at different temperatures is a protection technique for operations involving the aortic arch. In combination with selective cerebral perfusion, higher arrest temperatures for the remaining body may be permitted. However, the ischaemic/reperfusion injury (I/R) in various organ systems, other than the brain, related to the specific HCA temperature has so far not been evaluated.
  
  
  METHODS
  Fourteen pigs were randomly assigned to 60 min of sole HCA at 20 or 30 °C temperature, weaned from cardiopulmonary bypass (CPB) and followed 4h after HCA. Besides complex haemodynamic monitoring, laser-Doppler spectrophotometry for measuring capillary blood flow, tissue oxygen saturation and post-capillary venous filling pressures of the bowel was installed. At the end of experiment, organs were perfusion fixated and harvested.
  
  
  RESULTS
  During the entire experiment, haemodynamics revealed no differences between the groups. CPB bypass times were 177 ± 12 min in the 20 °C and 158 ± 11 min in the 30 °C group, respectively (p = 0.02). During reperfusion, lactate levels were initially significantly higher in the 30 °C animals (p = 0.001) but subsequently declined. Microcirculatory blood flow and velocity in the bowel were significantly reduced during cooling and reperfusion (p < 0.05), but were independent of final HCA temperature. Histological evaluation revealed significantly more oedema formation in the bowel wall of the 30 °C animals (p = 0.05).
  
  
  CONCLUSIONS
  Higher levels of circulating lactate levels during reperfusion indicate less effective organ protection at 30 than at 20 °C after 60 min of HCA. This is further substantiated by histological evidence for a more pronounced oedema inflammatory response within the bowel wall.
authors.affiliation: Division of Cardiac, Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Carl-Neuberg-Str 1, 30625 Hannover, Germany. Khaladj.Nawid@mh-hannover.de
authors.forename: Nawid
authors.initials: N
authors.lastname: Khaladj
authors.forename: Sven
authors.initials: S
authors.lastname: Peterss
authors.forename: Maximilian
authors.initials: M
authors.lastname: Pichlmaier
authors.forename: Malakh
authors.initials: M
authors.lastname: Shrestha
authors.forename: Reinhard
authors.initials: R
authors.lastname: von Wasielewski
authors.forename: Ludwig
authors.initials: L
authors.lastname: Hoy
authors.forename: Axel
authors.initials: A
authors.lastname: Haverich
authors.forename: Christian
authors.initials: C
authors.lastname: Hagl
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood; D001831:Body Temperature / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D002315:Cardiopulmonary Bypass / Q000379:methods; D002560:Cerebrovascular Circulation / Q000502:physiology; D004195:Disease Models, Animal; D004947:Esophagus / Q000503:physiopathology; D006324:Heart Arrest, Induced / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology; D007036:Hypothermia, Induced / Q000379:methods*; D019344:Lactic Acid / Q000097:blood; D017078:Laser-Doppler Flowmetry / Q000379:methods; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D012007:Rectum / Q000503:physiopathology; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control; D034421:Sus scrofa
chemical_list: D015415:Biomarkers; D002245:Carbon Dioxide; D019344:Lactic Acid; D010100:Oxygen