Cardiac Autonomic Function and Reactivity Tests in Physically Active Subjects with Moderately Severe COPD.

Area of Science:

• Cardiology
• Pulmonology
• Autonomic Neuroscience

Background:

• Chronic obstructive pulmonary disease (COPD) is associated with autonomic nervous system (ANS) dysfunction.
• ANS plays a crucial role in cardiac autonomic regulation.
• Pulmonary rehabilitation (PR) programs aim to improve patient outcomes in COPD.

Purpose of the Study:

• To assess autonomic function and cardio-vagal reactivity in COPD patients undergoing PR.
• To compare autonomic parameters between COPD patients and healthy controls.
• To identify specific markers of autonomic impairment in COPD.

Main Methods:

• Convenient sampling of 26 COPD patients and 22 age/gender-matched controls.
• Collection of R-R intervals at rest in a supine position.
• Calculation of resting heart rate variability (HRV) and baroreceptor sensitivity (BRS) using linear and nonlinear analyses.
• Performance of autonomic reactivity tests: deep breathing (DB), Valsalva maneuver (VM), and head-up tilt (HUT).

Main Results:

• Resting autonomic function parameters were generally reduced in COPD patients compared to controls.
• Statistically significant differences were observed in mean RR intervals, low frequency (LF), SD1, and approximate entropy (ApEn) (p < 0.05).
• Cardio-vagal indices from reactivity tests were comparable between COPD and control groups (p > 0.05).

Conclusions:

• Physically active COPD patients exhibit subtle autonomic impairments.
• These deficits are primarily identified through resting HRV indices.
• Autonomic reactivity tests did not reveal significant differences between COPD patients and controls.