title: Validation of frontal near-infrared spectroscopy as noninvasive bedside monitoring for regional cerebral blood flow in brain-injured patients.
abstract: OBJECTIVE
  Near-infrared spectroscopy (NIRS) offers noninvasive bedside measurement of direct regional cerebral arteriovenous (mixed) brain oxygenation. To validate the accuracy of this monitoring technique, the authors analyzed the statistical correlation of NIRS and CT perfusion with respect to regional cerebral blood flow (CBF) measurements.
  
  
  METHODS
  The authors retrospectively reviewed all cases in which NIRS measurements were obtained at a single, academic neurointensive care unit from February 2008 to June 2011 in which CT perfusion was performed at the same time as NIRS data was collected. Regions of interest were obtained 2.5 cm below the NIRS bifrontal scalp probe on CT perfusion with an average volume between 2 and 4 ml, with mean CBF values used for purposes of analysis. Linear regression analysis was performed for NIRS and CBF values.
  
  
  RESULTS
  The study included 8 patients (2 men, 6 women), 6 of whom suffered subarachnoid hemorrhage, 1 ischemic stroke, and 1 intracerebral hemorrhage and brain edema. Mean CBF measured by CT perfusion was 61 ml/100 g/min for the left side and 60 ml/100 g/min for the right side, while mean NIRS values were 75 on the right and 74 on the left. Linear regression analysis demonstrated a statistically significant probability value (p<0.0001) comparing NIRS frontal oximetry and CT perfusion-obtained CBF values.
  
  
  CONCLUSIONS
  The authors demonstrated a linear correlation for frontal NIRS cerebral oxygenation measurements compared with regional CBF on CT perfusion imaging. Thus, frontal NIRS cerebral oxygenation measurement may serve as a useful, noninvasive, bedside intensive care unit monitoring tool to assess brain oxygenation in a direct manner.
authors.affiliation: Department of Neurosurgery, Mayo Clinic, Jacksonville, FL 32224, USA. philipp.taussky@gmail.com
authors.forename: Philipp
authors.initials: P
authors.lastname: Taussky
authors.forename: Brandon
authors.initials: B
authors.lastname: O'Neal
authors.forename: Wilson P
authors.initials: WP
authors.lastname: Daugherty
authors.forename: Sothear
authors.initials: S
authors.lastname: Luke
authors.forename: Dallas
authors.initials: D
authors.lastname: Thorpe
authors.forename: Robert A
authors.initials: RA
authors.lastname: Pooley
authors.forename: Clay
authors.initials: C
authors.lastname: Evans
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Hanel
authors.forename: William D
authors.initials: WD
authors.lastname: Freeman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000175:diagnosis* / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods / Q000592:standards*; D010092:Oximetry / Q000379:methods / Q000592:standards; D019095:Point-of-Care Systems / Q000592:standards*; D012039:Regional Blood Flow / Q000502:physiology; D012189:Retrospective Studies; D019265:Spectroscopy, Near-Infrared / Q000379:methods / Q000592:standards*