The study aims to compare 2 different strategies used to setup non-invasive ventilation in patients with OCPD-OSA overlap.

With limited comparative data to support the different strategies, there is substantial variation across Europe and the United States in the methods used by clinicians to set up home non-invasive ventilation (NIV) for patients with chronic respiratory failure as a consequence of sleep disordered breathing. Indeed with few data to support the practice, many centres employ full montage polysomnography, which is not only a significant physical burden to the patient but also a financial burden to the healthcare provider in terms of the facilities required, staff training and equipment.

The investigators propose to undertake a randomised controlled trial to compare the clinical effectiveness, in terms of the change in daytime arterial partial pressure of carbon dioxide (PaCO2) at 3 months, of limited respiratory polygraphy and full polysomnography to set up NIV in patients with COPD-OSA overlap. Secondary outcome measures at 3 months will include overnight control of gas exchange, subjective sleep quality, health related quality of life and ventilator adherence. COPD-OSA overlap are a patient group that have a rising prevalence with limited data currently available detailing NIV set up, which wholly supports the rationale of using this increasingly important group as a target population for this trial.

Inclusion Criteria:

• COPD (as defined by GOLD criteria[4])
• OSA (ODI > 7.5 events/hr, AHI > 5events/hr)
• PaCO2 > 6 kPa
• BMI > 30 kg/m2

Exclusion Criteria:

• Decompensated respiratory failure (pH < 7.35)
• Inability to tolerate NIV (< 4 hours usage at in hospital titration)
• Contraindication to NIV
• Pregnancy
• Aged <18
• Significant physical or psychiatric co-morbidity that would prevent compliance with trial protocol