Nocturnal cerebral hemodynamics in snorers and in patients with obstructive sleep apnea: a near-infrared spectroscopy study.
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.
Pizza
Fabio
F
Department of Neurology, University Hospital Zürich, Switzerland.
Biallas
Martin
M
Wolf
Martin
M
Werth
Esther
E
Bassetti
Claudio L
CL
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
D006454:Hemoglobins; C100003:deoxyhemoglobin