title: Cerebral Resistance Index is less predictive in hypothermic encephalopathic newborns.
abstract: OBJECTIVE
  Neonatal hypoxic-ischaemic encephalopathy (HIE), if severe, may involve cerebral vasoparalysis. In HIE, Pourcelot's cerebral vascular resistance index (RI) below 0.55 (by Doppler ultrasound) from published literature at normothermia predicted poor outcome with a positive predictive value (PPV) of 84%. The aim of this study was to re-assess RI as a predictor of outcome in HIE during hypothermia.
  
  
  METHODS
  One hundred and twenty-five infants with HIE treated with hypothermia with outcome data and at least one measurement of RI at 24 h or later were included. Poor outcome was defined as death or severe disability.
  
  
  RESULTS
  Positive predictive value of low RI (≤ 0.55) was 60% (95% CI 45%, 74%), while the negative predictive value (NPV) was 78% (95% CI: 67%, 86%). The PPV during hypothermia is significantly lower than the pooled PPV of 84% (95% CI 73%, 91%) from all published studies of RI at normothermia. NPV during hypothermia and normothermia was similar [76%, (95% CI 69%, 82%)].
  
  
  CONCLUSIONS
  Low RI is significantly less predictive of poor outcome during hypothermia than normothermia. The lower PPV may be because hypothermia affects cerebral vasculature or protects the brain solely at a molecular and cellular level. Infants, who would have been predicted from their RI to have poorer outcome at normothermia, have better outcome when cooled.
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, UK.
authors.forename: Maja
authors.initials: M
authors.lastname: Elstad
authors.forename: Andrew
authors.initials: A
authors.lastname: Whitelaw
authors.forename: Marianne
authors.initials: M
authors.lastname: Thoresen
mesh_terms: D020771:Anterior Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002658:Developmental Disabilities / Q000209:etiology*; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D020925:Hypoxia-Ischemia, Brain / Q000150:complications / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D007231:Infant, Newborn; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D014463:Ultrasonography; D014655:Vascular Resistance