Laaban Jean-Pierre, Chailleux Edmond
Department of Pneumology, Hôtel-Dieu, 1 place du Parvis Notre-Dame, 75004 Paris, France.
Chest. 2005 Mar;127(3):710-5. doi: 10.1378/chest.127.3.710.
Daytime hypercapnia in patients with obstructive sleep apnea syndrome (OSAS) has a highly variable prevalence in the published studies, and is usually thought to be the consequence of an associated disease, COPD, or severe obesity.
To assess the prevalence of daytime hypercapnia in a very large population of adult patients with OSAS, free of associated COPD, and with a wide range of body mass index (BMI), and to evaluate the relationship between daytime hypercapnia and the severity of obesity and obesity-related impairment in lung function.
Retrospective analysis of prospectively collected data.
The database of the observatory of a national nonprofit network for home treatment of patients with chronic respiratory insufficiency (Association Nationale pour le Traitement a Domicile de l'Insuffisance Respiratoire Chronique) was used. Collected data at treatment initiation were age, apnea-hypopnea index, BMI, FEV(1), vital capacity (VC), and arterial blood gases. The study included 1,141 adult patients with OSAS treated in France with nocturnal nasal continuous positive airway pressure (CPAP), FEV(1) >/= 80% predicted, FEV(1)/VC >/= 70%, and absence of restrictive respiratory disease other than related to obesity.
The prevalence of daytime hypercapnia (Paco(2) >/= 45 mm Hg) before initiating CPAP therapy was 11% in the whole study population. The prevalence of daytime hypercapnia was 7.2% (27 of 377 patients) with BMI < 30, 9.8% (58 of 590 patients) with BMI from 30 to 40, and 23.6% (41 of 174 patients) with BMI > 40. Patients with daytime hypercapnia had significantly higher BMI values and significantly lower VC, FEV(1), and Pao(2) values than the normocapnic patients. Stepwise multiple regression showed that Pao(2), BMI, and either VC or FEV(1) were the best predictors of hypercapnia, but these variables explained only 9% of the variance in Paco(2) levels.
Daytime hypercapnia was observed in > 1 of 10 patients with OSAS needing CPAP therapy and free of COPD, and was related to the severity of obesity and obesity-related impairment in lung function. However, other mechanisms than obesity are probably involved in the pathogenesis of daytime hypercapnia in OSAS.
在已发表的研究中，阻塞性睡眠呼吸暂停综合征（OSAS）患者白天高碳酸血症的患病率差异很大，通常被认为是相关疾病、慢性阻塞性肺疾病（COPD）或严重肥胖的结果。
评估大量无COPD且体重指数（BMI）范围广泛的成年OSAS患者白天高碳酸血症的患病率，并评估白天高碳酸血症与肥胖严重程度以及肥胖相关肺功能损害之间的关系。
对前瞻性收集的数据进行回顾性分析。
使用全国慢性呼吸功能不全患者家庭治疗非营利网络观测站的数据库。治疗开始时收集的数据包括年龄、呼吸暂停低通气指数、BMI、第1秒用力呼气容积（FEV₁）、肺活量（VC）和动脉血气。该研究纳入了1141例在法国接受夜间鼻持续气道正压通气（CPAP）治疗的成年OSAS患者，FEV₁≥预测值的80%，FEV₁/VC≥70%，且无除肥胖相关以外的限制性呼吸疾病。
在整个研究人群中，开始CPAP治疗前白天高碳酸血症（动脉血二氧化碳分压[Paco₂]≥45 mmHg）的患病率为11%。BMI<30的患者白天高碳酸血症患病率为7.2%（377例患者中的27例），BMI为30至40的患者为9.8%（590例患者中的58例），BMI>40的患者为23.6%（174例患者中的41例）。与血二氧化碳正常的患者相比，白天高碳酸血症患者的BMI值显著更高，而VC、FEV₁和动脉血氧分压（Pao₂）值显著更低。逐步多元回归显示，Pao₂、BMI以及VC或FEV₁是高碳酸血症的最佳预测指标，但这些变量仅解释了Paco₂水平变异的9%。
在每10例需要CPAP治疗且无COPD的OSAS患者中，有超过1例存在白天高碳酸血症，且其与肥胖严重程度以及肥胖相关肺功能损害有关。然而，OSAS患者白天高碳酸血症的发病机制可能涉及肥胖以外的其他机制。
