[The role of breathing control disorder in the development of carbon dioxide retention in patients with obesity hypoventilation syndrome].
OBJECTIVE
To define the role of breathing control in the pathogenesis of carbon dioxide (CO(2)) retention in patients with obesity hypoventilation syndrome.


METHODS
10 obese obstructive sleep apnea syndrome (OSAS) patients were studied. They were separated according to their waking arterial partial pressure of CO(2) (PaCO(2)), 5 being eucapnic and 5 hypercapnic. Both groups had similar body mass index, apnea hypopnea index and normal lung function. The hypoxic (Delta P(0.1)/Delta SaO(2), Delta V(E)/Delta SaO(2)) and the hypercapnic response (Delta P(0.1)/Delta PaCO(2), Delta V(E)/Delta PaCO(2)) were tested before and during continuous positive airway pressure (CPAP) treatment (at 2, 4, 6 weeks).


RESULTS
Compared with the eucapnic patients, all the hypercapnic patients had lower Delta P(0.1)/Delta SaO(2) [(-0.04 +/- 0.02) cmH(2)O% vs (-0.14 +/- 0.03) cmH(2)O%], Delta V(E)/Delta SaO(2) [(-0.17 +/- 0.04) L x min(-1)% vs (-0.34 +/- 0.04) L x min(-1)%], Delta P(0.1)/Delta PaCO(2) [(0.23 +/- 0.1) cmH(2)O/mm Hg vs (0.49 +/- 0.1) cmH(2)O/mm Hg], Delta V(E)/Delta PaCO(2) [(1.32 +/- 0.7) L x min(-1) x mm Hg(-1) vs (2.18 +/- 0.81) L x min(-1) x mm Hg(-1)] and the Delta P(0.1)/Delta SaO(2), Delta V(E)/Delta SaO(2) were also lower than the normal value. After treatment with CPAP, the hypercapnic and the hypoxic response of the hypercapnic patients increased gradually, at about 4 approximately 6 week, both of them increased to the normal range, PaCO(2) showed a complete return to eucapnia, their weight were unchanged.


CONCLUSIONS
The depressed breathing control play an important role in the development of CO(2) retention in OSAS patients, and the disorder in breathing control may be secondary to hypoxia, hypercapnia and sleep disorder related to the OSAS.
Han
F
F
Department of Respirology, The People's Hospital, Beijing Medical University, Beijing 100044.
Chen
E
E
Wei
H
H
Ding
D
D
He
Q
Q
D000328:Adult; D002245:Carbon Dioxide / Q000097:blood*; D045422:Continuous Positive Airway Pressure; D005260:Female; D006801:Humans; D007040:Hypoventilation / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D012125:Respiratory Center / Q000503:physiopathology*; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*
D002245:Carbon Dioxide