Clinical benefit of chronic non-invasive ventilation in severe stable COPD: a matter of persistent hypercapnia improvement

Purpose In patients with chronic obstructive pulmonary disease (COPD) treated with chronic non-invasive ventilation (NIV), the relation between improvements in nocturnal transcutaneous partial pressure of CO2 (PtcCO2) and daytime arterial partial pressure of CO2 (PaCO2) remains uncertain. Also, to what extent improvements in nocturnal PtcCO2 result in better health-related quality of life (HRQL), exercise capacity, lung function and survival has not been investigated. Patients and methods Patients with COPD who were initiated on chronic NIV were prospectively followed for 6 months. Daytime PaCO2 and nocturnal PtcCO2 were measured before NIV initiation. NIV targeted normocapnia (PaCO2/mean PtcCO2<6.0 kPa) or to reduce baseline values >20%. HRQL was measured with the Severe Respiratory Insufficiency questionnaire (SRI) and exercise capacity with the 6-min walk test (6MWT). Patients were divided into three groups: group 1: neither PtcCO2 nor PaCO2 reductions reached the target; group 2: both PtcCO2 and PaCO2 targets were reached; group 3: only PtcCO2 target was reached. Results 177 participants were included with both transcutaneous and daytime gas exchange data. In total, 66% reached nocturnal gas exchange targets. However, in only 17%, this also resulted in substantial daytime PaCO2 reduction (group 2). Compared with group 1, these patients had higher baseline PtcCO2 (7.4±0.7 vs 8.2±1.9 kPa, p=0.012) and better NIV usage (6.2±2.8 vs 8.3±2.4 hours, p=0.010). Despite comparable NIV settings, the forced expiratory volume in 1 s and 6MWT improved only in group 2, and only these participants reached a clinically relevant improvement on the SRI and experienced improved survival. Conclusion Patients with COPD who can maintain improved ventilation by nocturnal NIV during daytime spontaneous breathing are most likely to experience relevant benefits on HRQL, exercise capacity, lung function and survival. No data are available. The data used for this analysis were obtained from two clinical trials ([NCT02652559][1] and [NCT03053973][2]). Request for data sharing should be directed to the principal investigators of those trials. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT02652559&atom=%2Fthoraxjnl%2Fearly%2F2025%2F01%2F01%2Fthorax-2024-221899.atom [2]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT03053973&atom=%2Fthoraxjnl%2Fearly%2F2025%2F01%2F01%2Fthorax-2024-221899.atom