title: pH-stat versus alpha-stat acid-base management strategy during hypothermic circulatory arrest combined with embolic brain injury.
abstract: BACKGROUND
  There is some evidence of beneficial metabolic effects associated with the pH-stat than with alpha-stat perfusion strategy, but this is tempered by a likely increased risk of embolism to the brain, especially in adult patients. We investigated this possible adverse effect in an experimental model that combined hypothermic circulatory arrest (HCA) and embolic brain injury.
  
  
  METHODS
  Twenty-four female juvenile pigs undergoing 25 minutes of HCA at a brain temperature of 18 degrees C were assigned to either alpha-stat (n = 12) or pH-stat (n = 12) strategy during cardiopulmonary bypass. Before the initiation of HCA, the descending aorta was clamped and 200 mg of albumin-coated polystyrene microspheres (250 to 750 microm in diameter) were injected into the isolated aortic arch in both groups.
  
  
  RESULTS
  The 7-day survival rate was 75% in the pH-stat group and 50% in the alpha-stat group (p = 0.40). The pH-stat group had significantly better behavioral scores on postoperative days 5 (p = 0.03) and 6 (p = 0.04). The pH-stat strategy was associated with better postoperative intracranial pressures and histopathologic scores, but such differences did not reach statistical significance. The alpha-stat group had lower brain glucose concentrations postoperatively as well as higher brain lactate/glucose and lactate/pyruvate ratios
  
  
  CONCLUSIONS
  These results suggest that pH-stat strategy does not cause any worse brain injury than the alpha-stat strategy. Indeed, the pH-stat strategy is associated with a slightly better outcome compared with the alpha-stat strategy, even in the setting of cerebral embolization. This observation suggests that the pH-stat strategy could also be used in adults during deep hypothermic cardiopulmonary bypass despite the increased risk of intraoperative cerebral embolization.
authors.affiliation: Department of Surgery, Oulu University Hospital, University of Oulu, Oulu, Finland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Dahlbacka
authors.forename: Janne
authors.initials: J
authors.lastname: Heikkinen
authors.forename: Timo
authors.initials: T
authors.lastname: Kaakinen
authors.forename: Päivi
authors.initials: P
authors.lastname: Laurila
authors.forename: Vilho
authors.initials: V
authors.lastname: Vainionpää
authors.forename: Kai
authors.initials: K
authors.lastname: Kiviluoma
authors.forename: Timo
authors.initials: T
authors.lastname: Salomäki
authors.forename: Hannu
authors.initials: H
authors.lastname: Tuominen
authors.forename: Pasi
authors.initials: P
authors.lastname: Ohtonen
authors.forename: Fausto
authors.initials: F
authors.lastname: Biancari
authors.forename: Pasi
authors.initials: P
authors.lastname: Lepola
authors.forename: Tatu
authors.initials: T
authors.lastname: Juvonen
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D002545:Brain Ischemia / Q000517:prevention & control; D002245:Carbon Dioxide / Q000097:blood; D002315:Cardiopulmonary Bypass; D004569:Electroencephalography; D005947:Glucose / Q000378:metabolism; D006324:Heart Arrest, Induced / Q000009:adverse effects*; D006863:Hydrogen-Ion Concentration; D020766:Intracranial Embolism / Q000209:etiology*; D019344:Lactic Acid / Q000378:metabolism; D010101:Oxygen Consumption; D013552:Swine
chemical_list: D002245:Carbon Dioxide; D019344:Lactic Acid; D005947:Glucose