This study will assess the impact the BREATHE device provides on post-exertion recovery time in COPD patients when used during and/or after performing an Activity of Daily Living simulation. It will also establish equivalency with BiPAP machines.

Study Overview: Potential subjects who are clinically stable COPD patients with 30% ≤ FEV1 < 50% (COPD GOLD criteria stage 3), will be enrolled. Following consent procedures, interested participants will be screened for eligibility. Eligible subjects will be invited to the test facility for four (4) visits. During the first visit, baseline measurements will be made. In the subsequent three (3) sessions, subjects will be asked to perform two (2) tests (BiPAP Equivalency Test and Activity of Daily Living Simulation). Baseline evaluation techniques will include spirometry, a Six Minute Walk Test (6MWT) (which produces a Six Minute Walk Distance, or 6MWD), and finally, a baseline treadmill test. Prior to the baseline treadmill test, Borg Scores will be measured. The subjects will then be asked to walk at a comfortable speed on the treadmill. The incline will be increased each minute by either 1% (Baseline 6MWD < 250m) or 2% (Baseline 6MWD >250m) until they reached a Borg score of 7.

In subsequent visits, subjects will be randomly assigned each of six tests including: treadmill tests that repeat the baseline treadmill test with a) the prototype BREATHE device, b) a standard BiPAP system, or c) a placebo inhaler used during recovery; and Glittre ADL tests where the subject either has access to the BREATHE device a) withheld, b) during recovery, and c) during test performance and recovery. The primary endpoint in each of these tests is the recovery time (return to 0 Borg, "No difficulty breathing"). SpO2, heart rate, respiration rate, and total test times will also be recorded during each test.

BiPAP Equivalency Test: Subjects will perform exercise tests identical to the treadmill tests from the baseline test. However, in these tests, after they reach a Borg score of 7, they will be allowed to recover with a) the prototype BREATHE system, b) a standard BiPAP machine, and c) a placebo inhaler until they are fully recovered (Borg: 0).

Activity of Daily Living Simulation: Subjects will be asked to complete Glittre-ADL tests. This test is a standard COPD functional performance instrument. At the beginning of each test, participants will be instructed to rise from a chair and walk 10 meters, ascending a 2-step rise about half-way along that distance, to reach a shelving unit. The shelves will be positioned at shoulder and waist height. The participant will move 3 cartons, each weighing 1 kg, from the upper to the lower shelf and then to the floor.

The sequence is then reversed so that each carton is returned to the top shelf before the participant returns to the starting position at the chair. At that time the participant sits down and then immediately rises to begin the next lap. The test ends when the participant completes 5 of these laps. Participants are told to perform the test as quickly as possible. Rests are allowed but participants are told to resume activity as soon as possible. During the test, participants will wear a backpack filled with a 2.5 (women) or 5 kg (men) weight. The 2.5 kg weight simulates the weight of a supplemental oxygen unit, which can be exchanged for the weight when appropriate. This allows the addition of oxygen for future tests without affecting the integrity of the test.

Three different Glittre-ADL tests will be completed. In these sessions, the BREATHE system will a) not be available, b) be available for use during post-exertion recovery, and c) be available for use throughout the test and recovery period. Borg scores will be measured after each minute of exercise and every 30 seconds during seated recovery until the subject is fully recovered (Borg: 0).

Inclusion Criteria:

• Subject is age 21 to 85
• Clinically stable
• Diagnosis of COPD following ERS-ATS guidelines 2011 update with GOLD criteria stage 3 ("Severe"), 30% ≤ FEV1 < 50%
• Capable of giving informed consent
• Willing and able to comply with the test program as directed by staff.

Exclusion Criteria:

• Subject is not fluent in written or spoken English
• Has physical impairment that prevents the subject from being able to walk or stand
• Is acutely ill/medically complicated, as determined by the investigator.