Evaluation of a Portable Oxygen Concentrator During Ambulation for Patients Who Require Supplemental Oxygen (POC-LEAN)

Inclusion Criteria: 1. Informed consent obtained before any study-related activities. Study-related activities are any procedures that are carried out as part of the study, including activities to determine suitability for the study. 2. Male or female, age ≥ 18 years at the time of signing informed consent. 3. Diagnosed with COPD and currently in a stable state (at least 4 weeks since last exacerbation episode22). 4. Current prescription for long-term oxygen therapy. 5. Participants meet the criteria for pulse-dose portable oxygen delivery, defined as being mobile within the home and the qualifying blood gas study was performed at rest/ awake or during exercise. 6. Participants who can read and comprehend English. Exclusion Criteria: 1. Clinically unstable, in the investigator's opinion, which might jeopardize the participant's safety or compliance with the protocol. 2. Current oxygen therapy prescription for \>5 L/min continuous flow. 3. Known or suspected contraindication for pulse-dose oxygen. 4. Unable to complete 6MWTs, e.g., unstable angina and myocardial infarction during the previous month 5. Female who is pregnant, breast-feeding, or intends to become pregnant, or is of child-bearing potential and not using an adequate contraceptive method (adequate contraceptive measure as required by local regulation or practice).