Chronic obstructive pulmonary disease (COPD) is a progressive respiratory disorder characterized by persistent airflow limitation, significantly impacting morbidity and mortality worldwide. The disease is often associated with autonomic nervous system (ANS) dysfunction, which can adversely affect cardiac function and overall prognosis. This study investigates the relationship between heart rate variability (HRV), a non-invasive marker of autonomic regulation, and peripheral oxygen saturation (SpO