title: Low perfusion pressure during CPB may induce cerebral metabolic and ultrastructural changes.
abstract: BACKGROUND
  Recently we reported on cerebral metabolic changes suggesting ischemia in piglets during nitroprusside-induced low-pressure CPB. We here investigated whether a mean arterial pressure (MAP) of 40-45 mmHg could provoke similar changes by a NO-independent intervention.
  
  
  METHODS
  Piglets underwent 60 minutes normothermic followed by 90 minutes hypothermic CPB. The LP-group (n=8) had MAP of 40-45 mmHg by phentolamine while the HP-group (n=8) had MAP of 60-80 mmHg by norepinephrine. Cerebral glucose, lactate, pyruvate and glycerol were determined. In the last two animals of each group, cerebral tissue was examined by electron microscopy.
  
  
  RESULTS
  Cerebral lactate was higher in the LP-group than the HP-group during normothermic CPB. Compared with baseline, cerebral glucose of the LP-group decreased whereas lactate/pyruvate-ratio, lactate and glycerol-concentrations increased during normothermic CPB. In the HP-group these parameters remained unchanged. Electron microscopy showed 31.2% and 8.3% altered mitochondria in the cortical micrographs taken from the LP- and the HP-group, respectively (p<0.001).
  
  
  CONCLUSIONS
  MAP below 45 mmHg during CPB was associated with cerebral biochemical and morphological changes consistent with anaerobic metabolism and subcellular injury.
authors.affiliation: Department of Anesthesia and Intensive Care, Haukeland University Hospital, Bergen, Norway.
authors.forename: Oddbjørn
authors.initials: O
authors.lastname: Haugen
authors.forename: Marit
authors.initials: M
authors.lastname: Farstad
authors.forename: Reidar
authors.initials: R
authors.lastname: Myklebust
authors.forename: Venny
authors.initials: V
authors.lastname: Kvalheim
authors.forename: Stig
authors.initials: S
authors.lastname: Hammersborg
authors.forename: Paul
authors.initials: P
authors.lastname: Husby
mesh_terms: D000818:Animals; D015415:Biomarkers; D002545:Brain Ischemia / Q000209:etiology*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects* / Q000379:methods; D002540:Cerebral Cortex / Q000187:drug effects* / Q000648:ultrastructure; D006439:Hemodynamics; D007022:Hypotension / Q000209:etiology*; D015425:Myocardial Reperfusion; D010477:Perfusion; D012307:Risk Factors; D013552:Swine
chemical_list: D015415:Biomarkers