To compare the effects of high flow nasal oxygen with usual care during an outpatient 6-week pulmonary rehabilitation program after hospitalization for COPD exacerbation.

This is a pilot randomized controlled trial to compare the effects of high flow nasal oxygen with usual care during an outpatient 6-week pulmonary rehabilitation program after hospitalization for COPD exacerbation.

Inclusion Criteria:

1. Age 21 years and above
2. Known diagnosis of COPD based on history AND spirometry demonstrating post bronchodilator FEV1/FVC ratio <0.7
3. Currently admitted inpatient for an acute COPD exacerbation as the primary diagnosis
4. Fit to participate in exercise therapy as determined by both physician and physiotherapist
5. Has the mental capacity to follow instructions
6. Experience shortness of breath on exertion
7. Have decreased ability to carry out activities due to shortness of breath
8. Willing to participate in the exercise program

Exclusion Criteria:

1. Uncontrolled/ unstable medical conditions such as severe chronic heart failure that make exercise unsafe
2. Pulmonary disorder other than COPD
3. Physical conditions that preclude the ability to participate in exercise or may impair exercise performance.