- Clinical and/or overnight pulse oximetry evidence of obstructive sleep apnea (OSA). The Multivariate Apnea Prediction Questionnaire (MAP) will be given to all patients to assess the likelihood of OSA based on common symptoms of this disorder. While we recognize that this screening instrument was not evaluated specifically in COPD patients, it assesses common signs and symptoms of OSA. This tool has been shown to identify OSA with 95% sensitivity (63). In addition, the ODI 4% will be determined from the overnight pulse oximetry recording. Patients will be excluded if the MAP score is > 0.4 or if the ODI 4% is >15/hour, which is suggestive of the concomitant presence of obstructive sleep apnea.