title: Cerebrovascular Pressure Reactivity in Children With Traumatic Brain Injury.
abstract: OBJECTIVE
  Traumatic brain injury is a significant cause of morbidity and mortality in children. Cerebral autoregulation disturbance after traumatic brain injury is associated with worse outcome. Pressure reactivity is a fundamental component of cerebral autoregulation that can be estimated using the pressure-reactivity index, a correlation between slow arterial blood pressure, and intracranial pressure fluctuations. Pressure-reactivity index has shown prognostic value in adult traumatic brain injury, with one study confirming this in children. Pressure-reactivity index can identify a cerebral perfusion pressure range within which pressure reactivity is optimal. An increasing difference between optimal cerebral perfusion pressure and cerebral perfusion pressure is associated with worse outcome in adult traumatic brain injury; however, this has not been investigated in children. Our objective was to study pressure-reactivity index and optimal cerebral perfusion pressure in pediatric traumatic brain injury, including associations with outcome, age, and cerebral perfusion pressure.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  ICU, Royal Children's Hospital, Melbourne, Australia.
  
  
  METHODS
  Patients with traumatic brain injury who are 6 months to 16 years old, are admitted to the ICU, and require arterial blood pressure and intracranial pressure monitoring.
  
  
  METHODS
  None.
  
  
  RESULTS
  Arterial blood pressure, intracranial pressure, and end-tidal CO2 were recorded electronically until ICU discharge or monitoring cessation. Pressure-reactivity index and optimal cerebral perfusion pressure were computed according to previously published methods. Clinical data were collected from electronic medical records. Outcome was assessed 6 months post discharge using the modified Glasgow Outcome Score. Thirty-six patients were monitored, with 30 available for follow-up. Pressure-reactivity index correlated with modified Glasgow Outcome Score (Spearman ρ = 0.42; p = 0.023) and was higher in patients with unfavorable outcome (0.23 vs -0.09; p = 0.0009). A plot of pressure-reactivity index averaged within 5 mm Hg cerebral perfusion pressure bins showed a U-shape, reaffirming the concept of cerebral perfusion pressure optimization in children. Optimal cerebral perfusion pressure increased with age (ρ = 0.40; p = 0.02). Both the duration and magnitude of negative deviations in the difference between cerebral perfusion pressure and optimal cerebral perfusion pressure were associated with unfavorable outcome.
  
  
  CONCLUSIONS
  In pediatric patients with traumatic brain injury, pressure-reactivity index has prognostic value and can identify cerebral perfusion pressure targets that may differ from treatment protocols. Our results suggest but do not confirm that cerebral perfusion pressure targeting using pressure-reactivity index as a guide may positively impact on outcome. This question should be addressed by a prospective clinical study.
authors.affiliation: 1Department of Neurosurgery, Alfred Hospital, Melbourne, VIC, Australia. 2Department of Surgery, Central Clinical School, Monash University, Melbourne, VIC, Australia. 3Neurosurgical Unit, Department of Clinical Neurosciences, Cambridge University, Cambridge, United Kingdom. 4Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland. 5Clinical Technology Service, Paediatric Intensive Care Unit, Royal Children's Hospital, Parkville, VIC, Australia. 6Department of Surgery, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD. 7Department of Clinical Haematology, Alfred Hospital, Melbourne, VIC, Australia. 8Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC, Australia. 9Paediatric Intensive Care Unit, Royal Children's Hospital, Parkville, VIC, Australia. 10Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Lewis
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.forename: Bradley G
authors.initials: BG
authors.lastname: Carter
authors.forename: Jeffrey V
authors.initials: JV
authors.lastname: Rosenfeld
authors.forename: Eldho
authors.initials: E
authors.lastname: Paul
authors.forename: Nitesh
authors.initials: N
authors.lastname: Singhal
authors.forename: Warwick
authors.initials: W
authors.lastname: Butt
mesh_terms: D000293:Adolescent; D000367:Age Factors; D062186:Arterial Pressure / Q000502:physiology*; D001315:Australia; D001930:Brain Injuries / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D015600:Glasgow Coma Scale; D023261:Glasgow Outcome Scale; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007223:Infant; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D011379:Prognosis; D011446:Prospective Studies