The Cardiovascular Consequences of Sleep Apnea Plus COPD (Overlap Syndrome)

Participants randomized to the bi-level arm will be provided with an auto bi-level device that automatically delivers the required pressure. The settings in the auto bi-level will be minimum EPAP of 4 cmH2O, maximum IPAP of 24 cmH2O, and a range of pressure support between 6-10 cmH2O. For those participants who have been randomized to the bi-level group but have not successfully acclimated to the device with the automatic bi-level settings, we will conduct an in-lab titration of the bi-level therapy during the optional Overnight visit 2.

The dose of nocturnal oxygen in all participants in the oxygen therapy arm will be 2 liters/minute. Patients with daytime hypoxemia, measured as sustained desaturations below 89% during wake time and/or arterial blood PO2 ≤ 55 mmHg, will be excluded from this study (as specified in the exclusion criteria) for ethical reasons since withholding oxygen in hypoxemic patients would be at odds with standard of care.