title: Continuous monitoring of cerebrovascular pressure reactivity after traumatic brain injury in children.
abstract: OBJECTIVE
  We hypothesized that pressure reactivity index (PRx) values indicating preserved cerebrovascular pressure autoregulation would be associated with survival in children with traumatic brain injury (TBI). This hypothesis was tested in a prospective, blinded, observational, pilot study.
  
  
  METHODS
  Twenty-one children admitted between May 2006 and September 2008 with severe TBI necessitating invasive intracranial pressure monitoring were enrolled in this study. The PRx was continuously monitored as a moving, linear correlation coefficient between low-frequency waves of intracranial and arterial blood pressures. Positive values of PRx approaching 1 indicate impaired cerebrovascular pressure reactivity, whereas negative PRx values or values close to 0 indicate preserved cerebrovascular pressure reactivity. Survival was the primary outcome and was compared with the average PRx value obtained during the intracranial pressure-monitoring period.
  
  
  RESULTS
  PRx was associated with survival in this cohort; survivors (N = 15) had a mean PRx +/- SD of 0.08 +/- 0.19, and nonsurvivors (N = 6) had a mean PRx of 0.69 +/- 0.21 (P = .0009). In this sample, continuous PRx monitoring suggested impaired cerebrovascular pressure reactivity at low levels of cerebral perfusion pressure (CPP) and intact cerebrovascular pressure reactivity at higher levels of CPP.
  
  
  CONCLUSIONS
  Intact cerebrovascular pressure reactivity quantified with the PRx is associated with survival after severe head trauma in children. The PRx is CPP dependent in children. The PRx may be useful for defining age-specific and possibly patient-specific optimal targets for CPP after TBI.
authors: Division of Pediatric Anesthesiology and Critical Care Medicine, Johns Department of aAnesthesiology and Critical Care, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21287, USA. kbrady5@jhmi.edu
authors: Ken M
authors: KM
authors: Brady
authors: Donald H
authors: DH
authors: Shaffner
authors: Jennifer K
authors: JK
authors: Lee
authors: R Blaine
authors: RB
authors: Easley
authors: Peter
authors: P
authors: Smielewski
authors: Marek
authors: M
authors: Czosnyka
authors: George I
authors: GI
authors: Jallo
authors: Anne-Marie
authors: AM
authors: Guerguerian
mesh_terms: D000293:Adolescent; D001794:Blood Pressure / Q000502:physiology*; D001930:Brain Injuries / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D015170:Cerebrospinal Fluid Pressure; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003128:Coma / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D005260:Female; D015600:Glasgow Coma Scale; D006706:Homeostasis / Q000502:physiology; D017052:Hospital Mortality; D006801:Humans; D007223:Infant; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008991:Monitoring, Physiologic; D010865:Pilot Projects; D011379:Prognosis