Near-infrared spectroscopy measurement of cerebral oxygenation in obstructive sleep apnea syndromes. Preliminary results.

Preliminary results. This study assessed cerebral oxygenation in four obstr uctive steep apnea syndrome (SAOS) patients (age = 51.8 +/- 15 years, apnea -hypopnea index = 68-125 per hour), during sleep and waking time, using nea r infrared spectoscopy (NIRS), during a standard polysomnography. Oxyhemogl obin (HbO(2), reflecting cerebral oxygenation), total hemoglobin (Hbt, refl ecting cerebral blood volumes) and cerebral oxygen saturation (SaO(2)c = Hb O(2/) Hbt), were compared to the data obtained in four snorers not presenti ng apneas (age = 51.8 +/- 6.6, apnea-hypopnea index = 2.6-6.2 per hour) exa mined in the same way. The main result was that HbO(2) values were reduced in SAGS patients, both during steep (at stage 2 : 52.54 +/- 9.60 mu mol/L v ersus 73.80 +/- 11.70 mu mol/L) and during waking state (53.67 +/- 7.20 mu mol/L Versus 63.05 +/- 5.55 mu mol/L). Hbt was also reduced in apneic patie nts as compared to snorers during waking state (72.73 +/- 13.90 mu mol/L ve rsus 96.05 +/- 6.30 mu mol/L). During sleep, Hbt increased in a similar way for snorers and apneics (12.4 % versus 13 %), whereas HbO(2) values were c onstant for apneics. SaO(2)c paralleled SaO(2)p in snorers and apneics, val ues far SaO(2)c being 20-30 % lower than values for SaO(2)p. The difference in the Values was probably due to the use of different monitoring techniqu es. Cerebral oxygenation and cerebral blood volumes were continuously low i n apneic patients, and peripheral hypoxia was associated with same-range ce rebral hypoxia. Cerebral hemodynamic mechanisms related to sleep, although in part efficient in apneic patients, were not able to increase cerebral ox ygenation up to normal valves. (C) 2000 Editions scientifiques et medicales Elsevier SAS.