[Respiratory control during sleep and the development of nocturnal hypoxia in patients with obstructive sleep apnea hypopnea syndrome].
OBJECTIVE
It is assumed that the reduced ventilatory control during sleep may be related to the nocturnal hypoxia in patients with obstructive sleep apnea hypopnea syndrome (OSAHS) and daytime CO(2) retention.


METHODS
Oxygen desaturation index (ODI(4)), sleep time spent when SaO(2) was below 90% (SIT(90)), the lowest SaO(2) (LSaO(2)) and the mean SaO(2) (MSaO(2)) during sleep were measured in 24 OSAHS patients with daytime PaCO(2) > or = 45 mm Hg and 39 with PaCO(2) < 45 mm Hg. Hypoxic (DeltaP(0.1)/DeltaSaO(2)) and hypercapnic (DeltaP(0.1)/DeltaPaCO(2)) responsiveness were measured in 11 eucapnic and 4 hypercapnic patients during wakefulness, NREM and REM sleep stages.


RESULTS
Compared with the eucapnic patients, all the hypercapnic patients had more severe hypoxia during sleep (P < 0.05). Although both groups had similar chemical responsiveness during wakefulness, the hypercapnic patients had lower DeltaP(0.1)/DeltaSaO(2) and DeltaP(0.1)/DeltaPaCO(2) during both REM and NREM sleep (P < 0.05).


CONCLUSIONS
The depressed chemical responsiveness during sleep plays an important role in the development of nocturnal hypoxia in OSAHS patients with daytime CO(2) retention.
Han
Fang
F
Department of Respiratory Medicine, Peking University People's Hospital, Beijing 100044, China.
Wei
Hai-lin
HL
Zhang
Yong-hui
YH
Zhang
Yang
Y
Li
Jing
J
Dong
Xiao-song
XS
He
Quan-ying
QY
Chen
Er-zhang
EZ
Ding
Dong-jie
DJ
D002245:Carbon Dioxide / Q000097:blood; D006801:Humans; D000860:Hypoxia / Q000209:etiology*; D010100:Oxygen / Q000097:blood; D012119:Respiration; D012890:Sleep / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*
D002245:Carbon Dioxide; D010100:Oxygen