Oxygen therapy in COPD patients with isolated nocturnal hypoxemia; comparison of quality of life and sleep between bronchitis and emphysema phenotype: A prospective observational study

Background: COPD is a heterogeneous disease composed by two main phenotypes: bronchitis (COPDb) and emphysema (COPDe) with different clinical presentation, physiology, imaging, response to therapy and decline in lung function. The aim of this study is to evaluate whether nocturnal hypoxemic COPDb and COPDe have a different behaviour during sleep and the effect of nocturnal oxygen supplementation (nO₂LT).

Materials and methods: 75 COPDb and 120 COPDe were enrolled. All patients performed polysomnography, Pittsburgh and Maugeri Foundation Respiratory Failure questionnaire, and pulmonary function before and after six months of nO₂LT.

Results: At baseline, compared to COPDb, COPDe have decreased sleep efficiency (SE) (67.5±6% vs. 76.9±3% p<0.05) and higher arousals (A/I) (18.1±3 event/h vs. 8.7±1 event/h p<0.05). Oxygen desaturation index (ODI) was increased during REM (7.1±1 event/h vs. 2.3±0.5 event/h p<0.05). nO₂LT in COPDe improves SE (77±4% vs. 67.5±6% p<0.05) and decreases A/I (9±5 event/h vs. 18.1±3 event/h p<0.05). ODI during REM (3.5±2 event/h vs. 7.1±1 p<0.05) decreases and quality of life (QoL) improves (MFR-28 total 56±22 vs 45±20 p<0.05), due to an improvement in cognitive abilities (45±30 vs 33±31 p<0.05) and daily activities (61±29 vs 53±21 p>0.05). In COPDb nO₂LT reduces ST90 (15±6% vs. 43±8% p<0.05) less than in COPDe (15±6% vs. 8±4% p<0.05); improves A/I (10±2 event/h vs. 8.7±1 p<0.05) and there is no evidence of an improvement in QoL.

Conclusions: Six months of nO₂LT improve quality of life in COPDe, not in COPDb. We found a difference in sleep quality between COPDe and COPDb.