Clinical impact of routine sleep assessment by peripheral arterial tonometry in patients with COPD

Abstract

Background Coexisting obstructive sleep apnoea (OSA) in patients with COPD, defined as overlap syndrome (OVS), is prevalent and underdiagnosed. Routine assessment of OSA is not common practice in COPD care. Our study assessed the clinical impact of sleep assessment by peripheral arterial tonometry (PAT) in COPD patients. Methods 105 COPD patients (mean age 68.1±9 years, body mass index (BMI) 28.3±6.0 kg·m−2, 44% males, Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I to IV in 2%, 40%, 42% and 16%, respectively) underwent assessment at an outpatient COPD clinic including anthropometrics, arterial blood gas (ABG) and spirometry in this clinical cohort study. PAT-based sleep studies were performed. Predictors of OVS and ABG were determined. Rapid eye movement (REM) sleep-related OSA (REM-OSA) was analysed in OVS. Results 49 COPD patients (47%) suffered from moderate to severe OSA (OVS group, mean apnoea–hypopnoea index 30.8±18 events·h−1, REM-oxygen desaturation index (REM-ODI) 26.9±17 events·h−1). OVS was more prevalent in males compared to females (59% and 37%, p=0.029, respectively). Age (70.1±8 versus 66.3±10 years), BMI (30.0±6 versus 26.4±7 kg·m−2) and hypertension prevalence (71% versus 45%) were elevated (all p<0.03, respectively), while deep sleep (12.7±7% and 15.4±6%, p=0.029) and mean overnight oxygenation (90.6±3% and 92.3±2%, p=0.003) were lower in OVS compared to COPD alone. REM-ODI was independently associated with daytime arterial carbon dioxide tension (PaCO2) (β=0.022, p<0.001). REM-OSA was associated with an elevated prevalence of atrial fibrillation compared to no REM-OSA (25% and 3%, p=0.022). Conclusions OVS was highly prevalent, specifically in obese males. REM-related OSA showed strong association with elevated daytime PaCO2 and prevalent cardiovascular disease. PAT was feasible for sleep assessment in COPD.