Kawata Naoko, Tatsumi Koichiro, Terada Jiro, Tada Yuji, Tanabe Nobuhiro, Takiguchi Yuichi, Kuriyama Takayuki
Department of Respirology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuou-ku, Chiba 260-8670, Japan.
Chest. 2007 Dec;132(6):1832-8. doi: 10.1378/chest.07-0673.
The pathogenesis of daytime hypercapnia (Paco2 >or= 45 mm Hg) may be directly linked to the existence of obstructive sleep apnea syndrome (OSAS) per se, although only some patients with OSAS exhibit daytime hypercapnia.
To investigate the prevalence of daytime hypercapnia in patients with OSAS; the association of daytime hypercapnia and obesity, obstructive airflow limitation, restrictive lung impairment, and severity of sleep apnea; and the response to continuous positive airway pressure (CPAP) therapy in a subset of subjects.
The study involved 1,227 patients with OSAS who visited a sleep clinic and were examined using polysomnography. As for the response to CPAP therapy, the patients were considered good responders if their daytime Paco2 decreased >or= 5 mm Hg and poor responders if it decreased < 5 mm Hg.
Fourteen percent (168 of 1,227 patients) exhibited daytime hypercapnia. These patients had significantly higher body mass index (BMI) and apnea-hypopnea index (AHI) values compared with normocapnic patients, while percentage of predicted vital capacity (%VC) and FEV(1)/FVC ratio did not differ between the two groups. Logistic regression analysis showed that only AHI was a predictor of daytime hypercapnia (p < 0.0001), while BMI (p = 0.051) and %VC (p = 0.062) were borderline predictors of daytime hypercapnia. Daytime hypercapnia was corrected in some patients (51%, 19 of 37 patients) with severe OSAS after 3 months of CPAP therapy.
The pathogenesis of daytime hypercapnia may be directly linked to sleep apnea in a subgroup of patients with OSAS.
日间高碳酸血症（动脉血二氧化碳分压[Paco2]≥45 mmHg）的发病机制可能与阻塞性睡眠呼吸暂停综合征（OSAS）本身的存在直接相关，尽管只有部分OSAS患者会出现日间高碳酸血症。
调查OSAS患者中日间高碳酸血症的患病率；日间高碳酸血症与肥胖、阻塞性气流受限、限制性肺功能损害及睡眠呼吸暂停严重程度之间的关联；以及部分受试者对持续气道正压通气（CPAP）治疗的反应。
该研究纳入了1227例到睡眠诊所就诊并接受多导睡眠图检查的OSAS患者。至于对CPAP治疗的反应，如果患者日间Paco2下降≥5 mmHg，则视为反应良好者；如果下降<5 mmHg，则视为反应不佳者。
14%（1227例患者中的168例）出现日间高碳酸血症。与血二氧化碳正常的患者相比，这些患者的体重指数（BMI）和呼吸暂停低通气指数（AHI）值显著更高，而两组间的预计肺活量百分比（%VC）和第1秒用力呼气容积（FEV1）/用力肺活量（FVC）比值并无差异。逻辑回归分析显示，只有AHI是日间高碳酸血症的预测指标（p<0.0001），而BMI（p=0.051）和%VC（p=0.062）是日间高碳酸血症的临界预测指标。3个月的CPAP治疗后，部分重度OSAS患者（51%，37例中的19例）的日间高碳酸血症得到纠正。
在一部分OSAS患者中，日间高碳酸血症的发病机制可能与睡眠呼吸暂停直接相关。
