title: Age, intracranial pressure, autoregulation, and outcome after brain trauma.
abstract: OBJECTIVE
  The object of this study was to investigate whether a failure of cerebrovascular autoregulation contributes to the relationship between age and outcome in patients following head injury.
  
  
  METHODS
  Data obtained from continuous bedside monitoring of intracranial pressure (ICP), arterial blood pressure (ABP), and cerebral perfusion pressure (CPP = ABP - ICP) in 358 patients with head injuries and intermittent monitoring of transcranial Doppler blood flow velocity (FV) in the middle cerebral artery in 237 patients were analyzed retrospectively. Indices used to describe cerebral autoregulation and pressure reactivity were calculated as correlation coefficients between slow waves of systolic FV and CPP (autoregulation index [ARI]) and between ABP and ICP (pressure reactivity index [PRI]). Older patients had worse outcomes after brain trauma than younger patients (p = 0.00001), despite the fact that the older patients had higher initial Glasgow Coma Scale scores (p = 0.006). When age was considered as an independent variable, it appeared that ICP decreased with age (p = 0.005), resulting in an increasing mean CPP (p = 0.0005). Blood FV was not dependent on age (p = 0.58). Indices of autoregulation and pressure reactivity demonstrated a deterioration in cerebrovascular control with advancing age (PRI: p = 0.003; ARI: p = 0.007).
  
  
  CONCLUSIONS
  An age-related decline in cerebrovascular autoregulation was associated with a relative deterioration in outcome in elderly patients following head trauma.
authors.affiliation: Academic Neurosurgical Unit, Addenbrooke's Hospital, Cambridge, United Kingdom. mc141@medschl.cam.ac.uk
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.forename: Marcella
authors.initials: M
authors.lastname: Balestreri
authors.forename: Luzius
authors.initials: L
authors.lastname: Steiner
authors.forename: Piotr
authors.initials: P
authors.lastname: Smielewski
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hutchinson
authors.forename: Basil
authors.initials: B
authors.lastname: Matta
authors.forename: John D
authors.initials: JD
authors.lastname: Pickard
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D001930:Brain Injuries / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000503:physiopathology; D012189:Retrospective Studies