title: Nocturnal cerebral hemodynamics in snorers and in patients with obstructive sleep apnea: a near-infrared spectroscopy study.
abstract: OBJECTIVE
  Sleep disordered breathing (SDB) of the obstructive type causes hemodynamic consequences, leading to an increased cerebrovascular risk. The severity of SDB at which detrimental circulatory consequences appear is matter of controversy. Aim of the present study is the investigation of cerebral hemodynamics in patients with SDB of variable severity using near-infrared spectroscopy (NIRS).
  
  
  METHODS
  N/A.
  
  
  METHODS
  Sleep laboratory.
  
  
  METHODS
  Nineteen patients with SDB.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Patients underwent nocturnal videopolysomnography (VPSG) coupled with cerebral NIRS. NIRS data were averaged for each patient, and a new method (integral) was applied to quantify cerebral hemodynamic alterations. Nocturnal VPSG disclosed various severities of SDB: snoring (7 patients, apnea-hypopnea index [AHI] = 2 +/- 2/h, range: 0.5-4.5); mild SDB (7 patients, AHI = 14 +/- 8/h, range: 6.3-28.6); and severe obstructive sleep apnea syndrome (5 patients, AHI = 79 +/- 20/h, range: 39.6-92.9). Relative changes of NIRS parameters were significantly larger during obstructive apneas (compared with hypopneas; mean deoxygenated hemoglobin [HHb] change of 0.72 +/- 0.23 and 0.13 +/- 0.08 micromol/L per sec, p value = 0.048) and in patients with severe SDB (as compared with patients with mild SDB and simple snorers; mean HHb change of 0.84 +/- 0.24, 0.02 +/- 0.09, and 0.2 +/- 0.08 micromol/L per sec, respectively, p value = 0.020). In this group, NIRS and concomitant changes in peripheral oxygen saturation correlated.
  
  
  CONCLUSIONS
  The results of this study suggest that acute cerebral hemodynamic consequences of SDB lead to a failure of autoregulatory mechanisms with brain hypoxia only in the presence of frequent apneas (AHI > 30) and obstructive events.
authors.affiliation: Department of Neurology, University Hospital Zürich, Switzerland.
authors.forename: Fabio
authors.initials: F
authors.lastname: Pizza
authors.forename: Martin
authors.initials: M
authors.lastname: Biallas
authors.forename: Martin
authors.initials: M
authors.lastname: Wolf
authors.forename: Esther
authors.initials: E
authors.lastname: Werth
authors.forename: Claudio L
authors.initials: CL
authors.lastname: Bassetti
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D012913:Snoring / Q000503:physiopathology*; D019265:Spectroscopy, Near-Infrared; D013223:Statistics as Topic
chemical_list: D006454:Hemoglobins; C100003:deoxyhemoglobin