title: Critical thresholds of intracranial pressure and cerebral perfusion pressure related to age in paediatric head injury.
abstract: BACKGROUND
  The principal strategy for managing head injury is to reduce the frequency and severity of secondary brain insults from intracranial pressure (ICP) and cerebral perfusion pressure (CPP), and hence improve outcome. Precise critical threshold levels have not been determined in head injured children.
  
  
  OBJECTIVE
  To create a novel pressure-time index (PTI) measuring both duration and amplitude of insult, and then employ it to determine critical insult thresholds of ICP and CPP in children.
  
  
  METHODS
  Prospective, observational, physiologically based study from Edinburgh and Newcastle, using patient monitored blood pressure, ICP, and CPP time series data. The PTI for ICP and CPP for 81 children, using theoretical values derived from physiological norms, was varied systematically to derive critical insult thresholds which delineate Glasgow outcome scale categories.
  
  
  RESULTS
  The PTI for CPP had a very high predictive value for outcome (receiver operating characteristic analyses: area under curve = 0.957 and 0.890 for mortality and favourable outcome, respectively) and was more predictive than for ICP. Initial physiological values most accurately predicted favourable outcome. The CPP critical threshold values determined for children aged 2-6, 7-10, and 11-15 years were 48, 54, and 58 mm Hg. respectively.
  
  
  CONCLUSIONS
  The PTI is the first substantive paediatric index of total ICP and CPP following head injury. The insult thresholds generated are identical to age related physiological values. Management guidelines for paediatric head injuries should take account of these CPP thresholds to titrate appropriate pressor therapy.
authors.affiliation: Regional Medical Physics Department, Newcastle General Hospital, Newcastle upon Tyne NE4 6BE, UK. i.r.chambers@ncl.ac.uk
authors.forename: I R
authors.initials: IR
authors.lastname: Chambers
authors.forename: P A
authors.initials: PA
authors.lastname: Jones
authors.forename: T Y M
authors.initials: TY
authors.lastname: Lo
authors.forename: R J
authors.initials: RJ
authors.lastname: Forsyth
authors.forename: B
authors.initials: B
authors.lastname: Fulton
authors.forename: P J D
authors.initials: PJ
authors.lastname: Andrews
authors.forename: A D
authors.initials: AD
authors.lastname: Mendelow
authors.forename: R A
authors.initials: RA
authors.lastname: Minns
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001794:Blood Pressure / Q000502:physiology*; D001921:Brain / Q000098:blood supply; D001925:Brain Damage, Chronic / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D001930:Brain Injuries / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology*; D002545:Brain Ischemia / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D023261:Glasgow Outcome Scale; D006801:Humans; D015601:Injury Severity Score; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008991:Monitoring, Physiologic; D011379:Prognosis; D011446:Prospective Studies; D012016:Reference Values; D015996:Survival Rate; D013997:Time Factors