This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Chronic obstructive pulmonary disease (COPD) patients who experience chronic low oxygen levels have an especially poor prognosis. More than 20 years ago, research studies demonstrated that chronic provision of supplemental oxygen to these patients provides dramatic benefits, including improved survival. Today, long-term oxygen therapy (LTOT) is considered to be the standard of care to hypoxemic COPD patients and about 750,000 patients in the United States it. Yet considerable controversy persists. Some authorities believe that ambulatory oxygen therapy is of benefit to the patient and, indeed, units easily carried by patients (weighing less than 5 lb) are commercially available. Yet the substantial majority of hypoxemic patients able to be ambulatory are supplied only with pressurized oxygen in E-cylinders, weighing about 22 lb and towed by the patient on a wheeled cart. This discrepancy between expert opinion and clinical practice exists because we do not know if patients provided with lightweight ambulatory systems have better compliance with oxygen prescription and increase their daily level of activity. We propose to perform a multicenter (7 sites) randomized trial in 100 hypoxemic COPD patients comparing the physiologic and clinical benefits of utilizing lightweight ambulatory oxygen systems versus portable E-cylinder systems. This will be a multi-center, unblinded, controlled trial randomizing 100 subjects across 7 clinical centers. Eligible subjects will be assigned control therapy (E-cylinder) or treatment therapy (light weight oxygen supply), in 1:1 allocation, using randomized blocks stratified by clinical center. Subjects will be evaluated during a two-week baseline period and then will be followed for 6 months post-randomization. There will be major evaluation periods at baseline, at three months and at six months. The primary outcome measure will be total daily hours of oxygen used and a secondary outcome measure will be level of activity. Patients will be monitored in their home by two computer-like devices. One will record minute-by-minute oxygen use of the patient's stationary oxygen concentrator. The other will record minute-by-minute oxygen use of the ambulatory source (lightweight device or E-cylinder). These devices can collect more than one month's data at a time. Study coordinators will visit the patient's home monthly to collect these monitors. Patients will also wear a pager-sized device on their belt for 2-3 week periods on three occasions during the study; this device (a tri-axial accelerometer) will collect minute-by-minute level of activity. Patients will also wear a device on their wrist for 3 two-day periods; a sensor taped to one of their fingers will measure the oxygen level in the blood. Patients will visit the study laboratory on 5 occasions. Procedures will include; ' history and physical examination ' pulmonary function testing in which patients will breathe forcefully and hold their breath for brief periods ' arterial and venous blood sampling for assessment of blood oxygenation and various blood chemistry and hematology tests ' exercise testing (both incremental & constant work rate testing) to assess cardiopulmonary risks and determine exercise tolerance ' oxygen titration at rest and exercise to determine an appropriate oxygen prescription. This will involve determining the oxygen flow rate required to maintain an adequate level of oxygen in the arterial blood both at rest and during exercise. To do this, a pulse oximeter will (noninvasively) measure oxygen level as the oxygen flow rate is adjusted both with the patient at rest and during a treadmill exercise test. ' 6 minute walk test to assess functional exercise tolerance ' questionnaires to determine quality of life, dyspnea severity, depression, mental status and coordination and cost-utility ' an education session will be conducted stressing the value of oxygen therapy and the benefits of increased activity Only patients currently oxygen supplies weighing over 10 pounds and carried in a cart for ambulation will be recruited, so that no patient will be asked to forego a lightweight ambulatory oxygen supply. Participating subjects will benefit by having access to a set of medical evaluations. The benefits to COPD patients as a group may be considerable if benefits of lightweight ambulatory oxygen supplies are clearly defined. The risks are modest; specifically, the monitoring devices have no known risks. The overall risk/benefit ratio is therefore favorable.
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