Evaluate subjects in an prospective observational study in which subjects will be screened and administered scientifically validated questionnaires at study entry and during the observation period at specified intervals to determine Quality Improvements through using the Breath Responsive Variable Bolus Oxygen Conserving Device with a Portable/Ambulatory Oxygen Source on improvements in functional capability, dyspnea, oxygen saturation, quality of life as primary endpoints, and portable oxygen source utilization, health care utilization as secondary endpoints.
