title: Extracellular lactate/pyruvate and glutamate changes in patients during per-operative episodes of cerebral ischaemia.
abstract: OBJECTIVE
  Temporary Internal Carotid Artery (ICA) clipping necessary during aneurysm surgery was used as a model to investigate metabolic changes in the human brain during defined episodes of ischaemia.
  
  
  METHODS
  An observational study using intracerebral monitors: PBO2 (Neurotrend) and microdialysis (CMA, Sweden).
  
  
  METHODS
  16 patients monitored during complex aneurysm surgery.
  
  
  METHODS
  Changes in extracellular concentrations of glucose, lactate, and glutamate and lactate/pyruvate ratio (L/P).
  
  
  RESULTS
  Mean age was 55. 10 patients presented with subarachnoid haemorrhage and 6 with mass effect (4 giant). Temporary ICA occlusion was required for dissection (n = 9), intraoperative rupture (n = 5) or aneurysmal thrombectomy (n = 2). The mean total duration was 15 minutes (range 4-52 minutes). No infarcts developed in the monitored regions. Microdialysis was unsuccessful in 3 patients and Neurotrend in 1. Patients were grouped according to the degree and duration of fall in PBO2: minimal brief falls were not associated with microdialysis changes (n = 5). More pronounced falls were associated with increases in L/P (n = 4). Only prolonged occlusions averaging 42 minutes (n = 3) with PBO2 sustained below 1 kPa were associated with rises in glutamate.
  
  
  CONCLUSIONS
  Brief temporary ICA occlusion caused an initial increased L/P. Glutamate increases were only seen after occlusion that was prolonged with PBO2 below 1.0 kPa.
authors.affiliation: Academic Department of Neurosurgery, Wolfson Brain Imaging Centre, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: R
authors.initials: R
authors.lastname: Kett-White
authors.forename: P J A
authors.initials: PJ
authors.lastname: Hutchinson
authors.forename: P G
authors.initials: PG
authors.lastname: al-Rawi
authors.forename: A K
authors.initials: AK
authors.lastname: Gupta
authors.forename: M T
authors.initials: MT
authors.lastname: O'Connell
authors.forename: J D
authors.initials: JD
authors.lastname: Pickard
authors.forename: P J
authors.initials: PJ
authors.lastname: Kirkpatrick
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers; D001921:Brain / Q000378:metabolism*; D002545:Brain Ischemia / Q000209:etiology / Q000378:metabolism*; D002343:Carotid Artery, Internal / Q000601:surgery*; D003399:Craniotomy; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D002532:Intracranial Aneurysm / Q000601:surgery*; D019344:Lactic Acid / Q000378:metabolism*; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D019635:Neurosurgical Procedures / Q000379:methods; D019289:Pyruvic Acid / Q000378:metabolism*; D013997:Time Factors
chemical_list: D015415:Biomarkers; D019344:Lactic Acid; D018698:Glutamic Acid; D019289:Pyruvic Acid