Heart Rate Variability and Peripheral Oxygen Saturation Levels in Chronic Obstructive Pulmonary Disease

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 (SpO₂) levels across different stages of COPD. The relevance of autonomic dysfunction in clinical practice is underscored by its potential to inform management strategies aimed at reducing cardiovascular risk and improving patient outcomes. This prospective, hospital-based cross-sectional analysis included 80 patients aged 40-75 years, diagnosed with COPD based on spirometry criteria. Participants were grouped into four severity categories (Stages I-IV) according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. HRV was assessed using five-minute recordings with a 16-channel polygraph machine, and SpO₂ levels were measured via pulse oximetry. Both time-domain (standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive differences (RMSSD)) and frequency-domain (low frequency (LF), high frequency (HF), and LF/HF ratio) HRV parameters were analyzed to evaluate autonomic function. Statistical analysis was performed using analysis of variance (ANOVA) to identify variations across the severity groups. The findings revealed a statistically significant decline in HRV indices with increasing COPD severity. Specifically, the standard deviation of normal-to-normal intervals (SDNN) decreased from an average of 64.74 ms in Stage I to 37.12 ms in Stage IV, and the root mean square of successive differences (RMSSD) declined from 60.41 ms to 39.36 ms. Frequency-domain analysis showed an increase in the low-frequency/high-frequency (LF/HF) ratio, from 0.69 in Stage I to 4.72 in Stage IV, indicating a shift toward sympathetic dominance. Additionally, SpO₂ levels decreased significantly from 98% in Stage I to 91.55% in Stage IV, reflecting the impact of hypoxemia on disease progression. This study highlights the importance of early detection and monitoring of autonomic imbalance in COPD patients. HRV and SpO₂ levels are identified as potential markers for disease severity, advocating for their integration into routine clinical evaluations. While significant associations were observed, the study's observational nature limits its ability to establish causation. Future research should focus on longitudinal assessments to better understand the prognostic value of HRV and SpO₂ and guide targeted therapeutic interventions. Addressing autonomic and respiratory dysfunctions holistically could enhance the quality of life and reduce the burden of comorbidities in COPD patients. While our findings highlight the potential value of integrating autonomic function assessment in clinical evaluations, it is important to note that the study's conclusions are drawn from a relatively small sample size. Further large-scale studies are necessary to validate these results and assess their applicability in broader clinical practice.