Inflammatory processes and effects of continuous positive airway pressure (CPAP) in overlap syndrome.

We aimed to compare serum levels of the inflammatory mediators including C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and asymmetric dimethylarginine (ADMA) in chronic obstructive pulmonary disease (COPD), obstructive sleep apnea syndrome (OSAS), and their coexistence called overlap syndrome (OVS). In addition, we planned to investigate changes of these mediators with the treatment of continuous positive airway pressure (CPAP) in OSAS and OVS. CRP, TNF-α, and ADMA levels were analyzed by ELISA method from blood samples withdrawn from patients with COPD (N = 25), OVS (N = 25), and moderate- to severe-stage OSAS (N = 25). First blood samples were taken in the morning after polysomnography application, and second blood samples were taken from OSAS and OVS patients who underwent regular CPAP treatment. In comparison of three groups prior to CPAP treatment, ADMA level in OSAS were significantly lower than in COPD (p = 0.009), but CRP and TNF-α were similar among groups. When we compared the parameters before and after CPAP treatment, the level of CRP in both OSAS and OVS decreased significantly (p = 0.02, p = 0.04), whereas TNF-α and ADMA levels did not display any significant differences. A decrease of serum CRP level in OVS and OSAS groups following effective CPAP treatment shows that CPAP is an effective treatment method for systemic inflammation.