title: The relationship between intracranial pressure and brain oxygenation in children with severe traumatic brain injury.
abstract: BACKGROUND
  Intracranial pressure (ICP) monitoring is a cornerstone of care for severe traumatic brain injury (TBI). Management of ICP can help ensure adequate cerebral blood flow and oxygenation. However, studies indicate that brain hypoxia may occur despite normal ICP and the relationship between ICP and brain oxygenation is poorly defined. This is particularly important for children in whom less is known about intracranial dynamics.
  
  
  OBJECTIVE
  To examine the relationship between ICP and partial pressure of brain tissue oxygen (PbtO2) in children with severe TBI (Glasgow Coma Scale score ≤ 8) admitted to Red Cross War Memorial Children's Hospital, Cape Town.
  
  
  METHODS
  The relationship between time-linked hourly and high-frequency ICP and PbtO2 data was examined using correlation, regression, and generalized estimating equations. Thresholds for ICP were examined against reduced PbtO2 using age bands and receiver-operating characteristic curves.
  
  
  RESULTS
  Analysis using more than 8300 hourly (n = 75) and 1 million high-frequency data points (n = 30) demonstrated a weak relationship between ICP and PbtO2 (r = 0.05 and r = 0.04, respectively). No critical ICP threshold for low PbtO2 was identified. Individual patients revealed a strong relationship between ICP and PbtO2 at specific times, but different relationships were evident over longer periods.
  
  
  CONCLUSIONS
  The relationship between ICP and PbtO2 appears complex, and several factors likely influence both variables separately and in combination. Although very high ICP is associated with reduced PbtO2, in general, absolute ICP has a poor relationship with PbtO2. Because reduced PbtO2 is independently associated with poor outcome, a better understanding of ICP and PbtO2 management in pediatric TBI seems to be needed.
authors: School of Child and Adolescent Health, Division of Neurosurgery, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, Western Cape, South Africa.
authors: Ursula K
authors: UK
authors: Rohlwink
authors: Eugene
authors: E
authors: Zwane
authors: A Graham
authors: AG
authors: Fieggen
authors: Andrew C
authors: AC
authors: Argent
authors: Peter D
authors: PD
authors: le Roux
authors: Anthony A
authors: AA
authors: Figaji
mesh_terms: D000293:Adolescent; D001921:Brain / Q000503:physiopathology*; D001930:Brain Injuries / Q000150:complications* / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D019586:Intracranial Hypertension / Q000209:etiology* / Q000503:physiopathology*; D007427:Intracranial Pressure; D010100:Oxygen / Q000378:metabolism*
chemical_list: D010100:Oxygen