Continuous positive airway pressure in clinically stable patients with mild‐to‐moderate obesity hypoventilation syndrome and obstructive sleep apnoea

Background and objective The use of continuous positive airway pressure ( CPAP ) treatment in patients with obesity hypoventilation syndrome ( OHS ) and obstructive sleep apnoea ( OSA ) was evaluated, and factors that might predict CPAP treatment failure were determined. Methods A sleep study was performed in 29 newly diagnosed, clinically stable OHS patients. CPAP treatment was commenced if the apnoea–hypopnoea index was >15. Lung function, night‐time oximetry, blood adipokine and C ‐reactive protein levels were assessed prospectively on enrollment and after 3 months. Treatment failure at 3 months was defined as daytime arterial partial pressure of carbon dioxide ( PaCO 2 ) >45  mm Hg and/or oxygen saturation ( SpO 2 ) <90% for >30% of the night‐time oximetry study. Results All patients had severe OSA (median apnoea–hypopnoea index = 74.7 (62–100) with a nocturnal mean SpO 2 of 81.4 ± 7), and all patients were treated with CPAP . The percentage of time spent below 90% saturation improved from 8.4% (0.0–39.0%) to 0.3% (0.4–4.0%). Awake PaCO 2 decreased from 50 (47–53) mm Hg to 43 (40–45) mm Hg . Seven patients failed CPAP treatment after 3 months. PaCO 2 at 1 month and mean night‐time SpO 2 during the first night of optimal CPAP were associated with treatment failure at 3 months (odds ratio 1.4 (1.03–1.98); P  = 0.034 and 0.6 (0.34–0.93); P  = 0.027). Conclusions CPAP treatment improves night‐time oxygenation and daytime hypoventilation in selected clinically stable OHS patients who also have OSA . Patients with worse night‐time saturation while on CPAP and higher daytime PaCO 2 at 1 month were more likely to fail CPAP treatment.