title: Noninvasive determination of brain tissue oxygenation during sleep in obstructive sleep apnea: a near-infrared spectroscopic approach.
abstract: OBJECTIVE
  Recurrent apneas and hypoxemia during sleep in obstructive sleep apnea (OSA) are associated with profound changes in cerebral blood flow to the extent that cerebral autoregulation may be insufficient to protect the brain. Since the brain is sensitive to hypoxia, the cerebrovascular morbidity seen in OSA could be due to chronic, cumulative effects of intermittent hypoxia. Near-infrared spectroscopy (NIRS) has the potential to noninvasively monitor brain tissue oxygen saturation (SO2), and changes in concentration of oxyhemoglobin [O2Hb], deoxyhemoglobin [HHb] and total hemoglobin [tHb] with real-time resolution. We hypothesized that brain tissue oxygenation would be worse during sleep in OSA relative to controls and sought to determine the practical use of NIRS in the sleep laboratory.
  
  
  METHODS
  We evaluated changes in brain tissue oxygenation using NIRS during overnight polysomnography.
  
  
  METHODS
  Studies were conducted at University of Illinois, Chicago and Carle Hospital, Urbana, Illinois.
  
  
  METHODS
  Nineteen subjects with OSA and 14 healthy controls underwent continuous NIRS monitoring during polysomnography.
  
  
  RESULTS
  We observed significantly lower indexes of brain tissue oxygenation (SO2: 57.1 +/- 4.9 vs. 61.5 +/- 6.1), [O2Hb]: 22.8 +/- 7.7 vs. 31.5 +/- 9.1, and [tHb]: 38.6 +/- 11.2 vs. 48.6 +/- 11.4 micromol/L) in OSA than controls (all P < 0.05). However, multivariate analysis showed that the differences might be due to age disparity between the two groups.
  
  
  CONCLUSIONS
  NIRS is an effective tool to evaluate brain tissue oxygenation in OSA. It provides valuable data in OSA assessment and has the potential to bridge current knowledge gap in OSA.
authors.affiliation: Department of Medicine M/C 719, Section of Pulmonary, Critical Care and Sleep Medicine, University of Illinois at Chicago, 840 S Wood Street, Chicago, IL 60612, USA. cosolopa@uic.edu
authors.forename: Christopher O
authors.initials: CO
authors.lastname: Olopade
authors.forename: Edward
authors.initials: E
authors.lastname: Mensah
authors.forename: Rajarsi
authors.initials: R
authors.lastname: Gupta
authors.forename: Dezheng
authors.initials: D
authors.lastname: Huo
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Picchietti
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
authors.forename: Antonios
authors.initials: A
authors.lastname: Michalos
mesh_terms: D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D001921:Brain / Q000503:physiopathology*; D003626:Data Display; D005260:Female; D006452:Hemoglobinometry; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D002534:Hypoxia, Brain / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D010108:Oxyhemoglobins / Q000378:metabolism; D017286:Polysomnography; D012016:Reference Values; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D012984:Software; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation*
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin