title: Transcranial Doppler pulsatility index is not a reliable indicator of intracranial pressure in children with severe traumatic brain injury.
abstract: BACKGROUND
  The TCD-derived PI has been associated with ICP in adult studies but has not been well investigated in children. We examined the relationship between PI and ICP and CPP in children with severe TBI.
  
  
  METHODS
  Data were prospectively collected from consecutive TCD studies in children with severe TBI undergoing ICP monitoring. Ipsilateral ICP and CPP values were examined with Spearman correlation coefficient (mean values and raw observations), with a GEE, and as binary values (1 and 20 mm Hg, respectively).
  
  
  RESULTS
  Thirty-four children underwent 275 TCD studies. There was a weak relationship between mean values of ICP and PI (P = .04, r = 0.36), but not when raw observations (P = .54) or GEE (P = .23) were used. Pulsatility index was 0.76 when ICP was lower than 20 mm Hg and 0.86 when ICP was 20 mm Hg or higher. When PI was 1 or higher, ICP was lower than 20 mm Hg in 62.5% (25 of 40 studies), and when ICP was 20 mm Hg or higher, PI was lower than 1 in 75% (46 of 61 studies). The sensitivity and specificity of a PI threshold of 1 for examining the ICP threshold of 20 mm Hg were 25% and 88%, respectively. The relationship between CPP and PI was stronger (P = .001, r = -0.41), but there were too few observations below 50 mm Hg to examine PI at this threshold.
  
  
  CONCLUSIONS
  The absolute value of the PI is not a reliable noninvasive indicator of ICP in children with severe TBI. Further study is required to examine the relationship between PI and a CPP threshold of 50 mm Hg.
authors.affiliation: Division of Neurosurgery, School of Child and Adolescent Health, Red Cross Children's Hospital, University of Cape Town, Cape Town 7700, South Africa. anthony.figaji@uct.ac.za
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Figaji
authors.forename: Eugene
authors.initials: E
authors.lastname: Zwane
authors.forename: A Graham
authors.initials: AG
authors.lastname: Fieggen
authors.forename: Peter
authors.initials: P
authors.lastname: Siesjo
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Peter
mesh_terms: D000293:Adolescent; D001794:Blood Pressure / Q000502:physiology; D001929:Brain Edema / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy; D001930:Brain Injuries / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D008991:Monitoring, Physiologic; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D011673:Pulsatile Flow / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*