The chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) have been recently much focused as independent risks for cardiovascular disease. Furthermore, the complication of both has a worse prognosis compared with patients with only one of these diseases. However, the details of the underlying mechanisms of this worsened prognosis have not been clear. The cross-sectional study was conducted to examine whether the overlap of COPD augment the increase in arterial stiffness in subjects with OSA. If so, we examined the exaggeration of nocturnal hypoxemia and its related inflammation are related to this augmentation of increased arterial stiffness. In 524 male subjects with OSA diagnosed by polysomnography (apnea-hypopnea index >5/h) (52 ± 14 years old), the forced expiratory volume at 1 s/the forced vital capacity (FEV(1)/FVC) ratio, brachial-ankle pulse wave velocity (baPWV), blood C-reactive protein (CRP) and B-natriuretic peptide (BNP) levels were measured. The prevalence rate of COPD was 12% in this study subjects. Plasma BNP levels and the crude (median value, 17.2 vs. 14.1 m/s, p < 0.01) and adjusted value of baPWV were significantly higher in subjects with overlap syndrome than in those with OSA alone. However, parameters of nocturnal hypoxemia and serum CRP levels were similar between both groups. Thus, the overlap of COPD in patients with OSA augments increase in arterial stiffness without the exaggeration of nocturnal hypoxemia and inflammation. Even so, this augmentation may partially contribute to the increased cardiovascular risk in the overlap syndrome.

Obstructive sleep apnea (OSA) is not only a cause of hypertension; it also possibly affects the pathogenesis and progression of aortic disease because an inspiratory effort-induced increase in negative intrathoracic pressure generates mechanical stress on the aortic wall. The objective of the present study was to examine the incidence by location of OSA as a complication in patients with aortic aneurysm and patients with aortic dissection (AD). An overnight sleep study was conducted in the following study groups: the aortic disease group (n = 95) consisting of patients with thoracic aortic aneurysm (TAA, n = 32), patients with abdominal aortic aneurysm (AAA, n = 36), and patients with AD (n = 27); and a control group (n = 32), consisting of patients with coronary risk factors who were matched with the aortic disease group for age, gender, and body mass index (BMI). The 3% oxygen desaturation index (ODI) was significantly higher in all the TAA, AAA, and AD groups (P = 0.045, P = 0.003, and P = 0.005, respectively) than in the control group. The incidence of moderate to severe OSA [apnea hypopnea index (AHI) ≥15 events/h] was significantly higher in the first three groups (P = 0.026, P = 0.001, P = 0.003, respectively) than in the control group, while no significant difference was found between the TAA group and the AAA group with respect to these variables. Furthermore, no significant differences were found between the thoracic AD subgroup and the abdominal AD subgroup with respect to AHI and 3% ODI, as well as with respect to the incidences of moderate to severe OSA. Patients with TAA, patients with AAA, and patients with AD showed high incidences of moderate to severe OSA. Although this result suggests that OSA may be one of risks for aortic disease, unelucidated mechanism(s) other than negative intrathoracic pressure may be involved in the pathogenesis of aortic disease.

Improvement of the sympathovagal balance by CPAP therapy may be significantly related to decreased stiffness of the central to middle-sized arteries, independent of the changes in the blood pressure and vascular endothelial status.

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