title: Higher brain extracellular potassium is associated with brain metabolic distress and poor outcome after aneurysmal subarachnoid hemorrhage.
abstract: BACKGROUND
  Elevated brain potassium levels ([K+]) are associated with neuronal damage in experimental models. The role of brain extracellular [K+] in patients with poor-grade aneurysmal subarachnoid hemorrhage (aSAH) and its association with hemorrhage load, metabolic dysfunction and outcome has not been studied so far.
  
  
  METHODS
  Cerebral microdialysis (CMD) samples from 28 poor grade aSAH patients were analyzed for CMD [K+] for 12 consecutive days after ictus, and time-matched to brain metabolic and hemodynamic parameters as well as corresponding plasma [K+]. Statistical analysis was performed using a generalized estimating equation with an autoregressive function to handle repeated observations of an individual patient.
  
  
  RESULTS
  CMD [K+] did not correlate with plasma [K+] (Spearman's ρ = 0.114, P = 0.109). Higher CMD [K+] was associated with the presence of intracerebral hematoma on admission head computed tomography, CMD lactate/pyruvate ratio >40 and CMD lactate >4 mmol/L (P < 0.05). In vitro retrodialysis data suggest that high CMD [K+] was of brain cellular origin. Higher CMD [K+] was significantly associated with poor 3-month outcome, even after adjusting for age and disease severity (P < 0.01).
  
  
  CONCLUSIONS
  The results of this pilot study suggest that brain extracellular [K+] may serve as a biomarker for brain tissue injury in poor-grade aSAH patients. Further studies are needed to elucidate the relevance of brain interstitial K+ levels in the pathophysiology of secondary brain injury after aSAH.
authors.forename: Ana Patrícia
authors.initials: AP
authors.lastname: Antunes
authors.forename: Alois Josef
authors.initials: AJ
authors.lastname: Schiefecker
authors.forename: Ronny
authors.initials: R
authors.lastname: Beer
authors.forename: Bettina
authors.initials: B
authors.lastname: Pfausler
authors.forename: Florian
authors.initials: F
authors.lastname: Sohm
authors.forename: Marlene
authors.initials: M
authors.lastname: Fischer
authors.forename: Anelia
authors.initials: A
authors.lastname: Dietmann
authors.forename: Peter
authors.initials: P
authors.lastname: Lackner
authors.forename: Werner Oskar
authors.initials: WO
authors.lastname: Hackl
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Ndayisaba
authors.forename: Claudius
authors.initials: C
authors.lastname: Thomé
authors.forename: Erich
authors.initials: E
authors.lastname: Schmutzhard
authors.forename: Raimund
authors.initials: R
authors.lastname: Helbok
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D005260:Female; D006706:Homeostasis; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D064926:Neurophysiological Monitoring; D010865:Pilot Projects; D011188:Potassium / Q000097:blood / Q000378:metabolism*; D011379:Prognosis; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000209:etiology / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D011188:Potassium