Impact of Obstructive Sleep Apnea on Cardiac Autonomic Control during the Respiratory Sinus Arrhythmia Maneuver in Patients with Chronic Obstructive Pulmonary Disease

Background: Chronic obstructive pulmonary disease (COPD) leads to pulmonary and systemic involvement that could damage the cardiac autonomic modulation (CAM), increasing cardiovascular risks and mortality rates. The obstructive sleep apnea (OSA) syndrome is also associated to harmed CAM. However, it is not clear if the presence of OSA in COPD patients causes an additional loss on the autonomic nervous function. Objective: To compare the responses of CAM during the respiratory sinus arrhythmia maneuver (RSA-M) between patients with OSA and COPD overlapped and COPD on isolation. Materials and Methods: Twenty-four patients (COPD, n = 11; OSA-COPD, n = 13) underwent pulmonary, cardiac function, and home sleep tests for diagnosis and staging of the disease. Heart rate (HR) and R-R intervals were collected during spontaneous breathing (SB) (sitting [10 min]) and the slow and deep breaths to trigger RSA-M (sitting [4 min]). Results: Both groups showed impaired responses when SB and RSA-M were compared. Both COPD and OSA-COPD patients showed increased sympathetic modulation, observed through increased LF (low frequency), and LF/HF ratio ( P < 0.05) and decreased HF (high frequency) ( P < 0.05), an opposite pattern to that expected for RSA-M. In addition, OSA-COPD showed worse HR variability complexity response on RSA-M (interaction effect, P < 0.05) and reduced spectral peak when contrasted with COPD alone ( P < 0.05). Conclusions: The results suggest the presence of both COPD and OSA lead to a negative impact on the autonomic control of HR and deep-breathing exercises. Future clinical trials that investigate the impact of breathing exercises on these autonomic indices should address the relevance of improving the autonomic balance in these patients.