Portable Oxygen Concentrator Improvements to Physical Activity, Oxygen Usage, and Quality of Life in Chronic Obstructive Pulmonary Disease Patients Using Long-term Oxygen Therapy (POC-STEP)

Inclusion Criteria: 1. Patient is 40 years or older. 2. Patient has a documented diagnosis of COPD. 3. Patient qualifies for continuous (24/7) long-term oxygen therapy. 4. Patient is prescribed oxygen at ≤ 5 L/min. 5. Patient is POC-naïve, i.e., has not used a POC prior to enrolling in this study. 6. Patient is able to tolerate pulsed oxygen therapy, i.e., oxygen delivered via a POC. 7. Patient is able to fully understand study information and provide signed informed consent and HIPAA authorization. Exclusion Criteria: 1. Patient's condition is contraindicated for the use of a POC. 2. Patient has uncontrolled or untreated sleep-disordered breathing that is uncontrolled or untreated. 3. Patient is unable to complete the 6-minute walk test. 4. Patient has a diagnosis (within less than two weeks prior to study entry) of pneumonia or respiratory infection, and/or acute bronchitis requiring antibiotics, or new/increased dose of systemic corticosteroids. 5. Patient has had thoracic surgery or another procedure in the six months prior to enrollment that is likely to cause instability of pulmonary status. 6. Patient has an open skin ulcer or rash where the activity monitor will be worn on the body. 7. Patient has a life expectancy \< 1 year. 8. Patient has non-COPD lung disease that may affect oxygenation or survival. 9. Patient has a planned intervention(s) requiring hospitalization within the three months of study participation. 10. Patient is pregnant or planning to become pregnant. 11. Patient is participating in a clinical study of a medical product and has not completed the required follow-up period. 12. Patient, in the opinion of the investigator, should be excluded from the study.