title: Impairment of cerebral autoregulation predicts delayed cerebral ischemia after subarachnoid hemorrhage: a prospective observational study.
abstract: OBJECTIVE
  Delayed cerebral ischemia (DCI) is a recognized contributor to unfavorable outcome after subarachnoid hemorrhage (SAH). Recent data challenge the concept of vasospasm as the sole cause of ischemia and suggest a multifactorial process with dysfunctional cerebral autoregulation as a component. We tested the hypothesis that early autoregulatory failure, detected using near-infrared spectroscopy-based index, TOxa and transcranial Doppler-based index, Sxa, can predict DCI.
  
  
  METHODS
  In this prospective observational study we enrolled consecutive patients with aneurysmal SAH that occurred <5 days from admission. The primary end point was the occurrence of DCI within 21 days of ictus. The predictive value of autoregulatory disturbances detected in the first 5 days was assessed using univarate proportional hazards model and a multivariate model.
  
  
  RESULTS
  Ninety-eight patients were included. Univariate analysis demonstrated increased odds of developing DCI when early autoregulation failure was detected (odds ratio [OR], 7.46; 95% confidence interval [CI], 3.03-18.40 and OR, 4.52; 95% CI, 1.84-11.07 for Sxa and TOxa, respectively) but not TCD-vasospasm (OR, 1.36; 95% CI, 0.56-3.33). In a multivariate model Sxa and TOxa remained independent predictors of DCI (OR, 12.66; 95% CI, 2.97-54.07 and OR, 5.34; 95% CI, 1.25-22.84 for Sxa and TOxa, respectively).
  
  
  CONCLUSIONS
  Disturbed autoregulation in the first 5 days after SAH significantly increases the risk of DCI. Autoregulatory disturbances can be detected using near-infrared spectroscopy and transcranial Doppler technologies.
authors.affiliation: Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, UK. k.budohoski@brodnowski.pl
authors.forename: Karol P
authors.initials: KP
authors.lastname: Budohoski
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.forename: Peter
authors.initials: P
authors.lastname: Smielewski
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kasprowicz
authors.forename: Adel
authors.initials: A
authors.lastname: Helmy
authors.forename: Diederik
authors.initials: D
authors.lastname: Bulters
authors.forename: John D
authors.initials: JD
authors.lastname: Pickard
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Kirkpatrick
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D019265:Spectroscopy, Near-Infrared; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000503:physiopathology*; D013997:Time Factors; D017585:Ultrasonography, Doppler, Transcranial; D020301:Vasospasm, Intracranial / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000503:physiopathology