title: Visualizing the pressure and time burden of intracranial hypertension in adult and paediatric traumatic brain injury.
abstract: OBJECTIVE
  To assess the impact of the duration and intensity of episodes of increased intracranial pressure on 6-month neurological outcome in adult and paediatric traumatic brain injury.
  
  
  METHODS
  Analysis of prospectively collected minute-by-minute intracranial pressure and mean arterial blood pressure data of 261 adult and 99 paediatric traumatic brain injury patients from multiple European centres. The relationship of episodes of elevated intracranial pressure (defined as a pressure above a certain threshold during a certain time) with 6-month Glasgow Outcome Scale was visualized in a colour-coded plot.
  
  
  RESULTS
  The colour-coded plot illustrates the intuitive concept that episodes of higher intracranial pressure can only be tolerated for shorter durations: the curve that delineates the duration and intensity of those intracranial pressure episodes associated with worse outcome is an approximately exponential decay curve. In children, the curve resembles that of adults, but the delineation between episodes associated with worse outcome occurs at lower intracranial pressure thresholds. Intracranial pressures above 20 mmHg lasting longer than 37 min in adults, and longer than 8 min in children, are associated with worse outcomes. In a multivariate model, together with known baseline risk factors for outcome in severe traumatic brain injury, the cumulative intracranial pressure-time burden is independently associated with mortality. When cerebrovascular autoregulation, assessed with the low-frequency autoregulation index, is impaired, the ability to tolerate elevated intracranial pressures is reduced. When the cerebral perfusion pressure is below 50 mmHg, all intracranial pressure insults, regardless of duration, are associated with worse outcome.
  
  
  CONCLUSIONS
  The intracranial pressure-time burden associated with worse outcome is visualised in a colour-coded plot. In children, secondary injury occurs at lower intracranial pressure thresholds as compared to adults. Impaired cerebrovascular autoregulation reduces the ability to tolerate intracranial pressure insults. Thus, 50 mmHg might be the lower acceptable threshold for cerebral perfusion pressure.
authors.affiliation: Department of Intensive Care Medicine, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium.
authors.forename: Fabian
authors.initials: F
authors.lastname: Güiza
authors.forename: Bart
authors.initials: B
authors.lastname: Depreitere
authors.forename: Ian
authors.initials: I
authors.lastname: Piper
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Citerio
authors.forename: Iain
authors.initials: I
authors.lastname: Chambers
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Jones
authors.forename: Tsz-Yan Milly
authors.initials: TY
authors.lastname: Lo
authors.forename: Per
authors.initials: P
authors.lastname: Enblad
authors.forename: Pelle
authors.initials: P
authors.lastname: Nillson
authors.forename: Bart
authors.initials: B
authors.lastname: Feyen
authors.forename: Philippe
authors.initials: P
authors.lastname: Jorens
authors.forename: Andrew
authors.initials: A
authors.lastname: Maas
authors.forename: Martin U
authors.initials: MU
authors.lastname: Schuhmann
authors.forename: Rob
authors.initials: R
authors.lastname: Donald
authors.forename: Laura
authors.initials: L
authors.lastname: Moss
authors.forename: Greet
authors.initials: G
authors.lastname: Van den Berghe
authors.forename: Geert
authors.initials: G
authors.lastname: Meyfroidt
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D062186:Arterial Pressure / Q000502:physiology*; D001296:Audiovisual Aids; D001930:Brain Injuries / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D023261:Glasgow Outcome Scale; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D019586:Intracranial Hypertension / Q000503:physiopathology*; D007427:Intracranial Pressure / Q000502:physiology*; D008875:Middle Aged; D008991:Monitoring, Physiologic; D011446:Prospective Studies; D013997:Time Factors; D055815:Young Adult