[Effect of noninvasive ventilation on chemoresponsiveness in patients with sleep apnea and chronic obstructive pulmonary disease].
OBJECTIVE
To investigate the effect of noninvasive ventilation on respiratory control in patients with chronic obstructive pulmonary disease (COPD) combined with sleep a apnea-hypopnea syndrome (SAHS)-overlap syndrome (OS).


METHODS
Ten body mass index, apnea-hypopnea index, and age-matched OSAHS patients, 5 being hypercapnic (PaCO(2) > 45 mm Hg) OSAHS patients with normal FEV(1)/FVC, and 5 being OSAHS patients with COPD and the mean FEV(1)/FVC of 59% +/- 6% underwent bi-level positive airway pressure (BiPAP) treatment. Hypoxic responses, including the ratio of the change in minute ventilation (DeltaVE) to the change in arterial oxygen saturation (DeltaSaO(2)), and hypercapnic responses (DeltaVE/DeltaPaCO(2) ratio) were tested during wakefulness before treatment and 6 weeks after the treatment.


RESULTS
Before treatment, the DeltaVE/DeltaSaO(2) ratios of the OS and OSAHS patients were (-0.023 +/- 0.049) L.min(-1).%(-1) and (-0.16 +/- 0.06) L.min(-1).%(-1) respectively, both lower than the laboratory normal value [(-0.35 +/- 0.21) L.min(-1).%(-1)]. The DeltaVE/DeltaPaCO(2) ratio of the OS patients was (0.54 +/- 0.16) L.mm Hg(-1), significantly lower than the normal value [(1.26 +/- 0.54) L.mm.Hg(-1), P < 0.05]. After receiving 6 weeks of noninvasive ventilation treatment, the hypoxic response of OSAHS patients were (-0.16 +/- 0.06) L.min(-1).%(-1), significantly higher than that before treatment [(-0.36 +/- 0.14) L.min(-1).%(-1)], and hypercapnic response of the OSAHS patients was (1.30 +/- 0.62) L.min(-1).mm Hg(-1), significantly lower than that before treatment [(1.78 +/- 0.93) L.min(-1).mm Hg(-1)], both bring within the normal ranges. In the patients with OS, the hypercapnic response was unchanged [(0.54 +/- 0.16) vs (0.51 +/- 0.23) L.min(-1).mm Hg(-1)], and the hypoxic responses increased significantly but still remained at a very low level [(-0.023 +/- 0.049) vs (-0.09 +/- 0.007) L.min(-1).%(-1)] after treatment.


CONCLUSIONS
Hypercapnic and hypoxic responses in patients with OS and in patients with OSAHS respond differently after pressure support ventilation. This indicates that depressed chemoresponsiveness in patients with OS may not be only a response to sleep-disordered breathing.
Wang
Hui-ling
HL
Department of Pulmonary Medicine, People's Hospital, Peking University, Beijing, China.
He
Zhong-ming
ZM
Li
Jing
J
Dong
Xiao-song
XS
Lü
Yun-hui
YH
Han
Xu
X
Wei
Cui-ying
CY
An
Pei
P
Wang
Li
L
Li
Guo-xiang
GX
He
Quan-ying
QY
Han
Fang
F
D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006935:Hypercapnia / Q000209:etiology / Q000503:physiopathology; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D012121:Respiration, Artificial / Q000379:methods*; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D016896:Treatment Outcome