Abstract
BACKGROUND: Supplemental oxygen is designed to raise alveolar PO2 to facilitate diffusion into arterial blood. Oxygen is generally delivered by nasal cannula either by continuous or pulsatile flow. Battery-powered portable oxygen concentrators (POCs) facilitate ambulation in patients experiencing exertional hypoxemia. In the United States, the Food and Drug Administration (FDA) clears these devices to be sold by physician prescription. Recently, however, lower-cost devices described as POCs have been advertised by online retailers. These devices lack FDA clearance and are obtained over the counter (OTC) without prescription. This study determined whether a selected group of OTC POCs have oxygen delivery characteristics suitable for use by hypoxemic patients.
METHODS: A metabolic simulator, capable of simulating a range of metabolic rates and minute ventilations, determined effects of oxygen supplementation delivered by a variety of devices on alveolar PO2. Devices tested included 3 OTC POCs, an FDA-cleared POC, and continuous-flow oxygen from a compressed oxygen cylinder. End-tidal PETO2, a surrogate of alveolar PO2, was determined at each of each device’s flow settings at 3 metabolic rates.
RESULTS: Continuous-flow tank oxygen yielded a linear PETO2 increase as flow increased, with progressively lower slope of increase for higher metabolic rate. The prescription POC device yielded similar PETO2 elevations, though with somewhat smaller elevations in pulse-dose operation. One OTC POC was only technically portable (no on-board battery); it provided only modest PETO2 elevation that failed to increase as flow setting was incremented. A second OTC POC produced only minimal PETO2 elevation. A third OTC POC, a pulsed-dose device, produced meaningful PETO2 increases, though not as great as the prescription device.
CONCLUSIONS: Only one of 3 OTC POCs tested was potentially of use by patients requiring ambulatory oxygen. Physicians and respiratory therapists should inform patients requiring portable oxygen that OTC devices may not meet their oxygenation requirements.
- exertional hypoxemia
- portable oxygen concentrator
- supplemental oxygen
- metabolic simulator
- long-term oxygen therapy
- online store
- nasal cannula
Footnotes
- Correspondence: Richard Casaburi PhD MD, Rehabilitation Clinical Trials Center, The Lundquist Institute at Harbor UCLA Medical Center, CDCRC Building, 1124 W. Carson Street, Torrance, CA 90502. E-mail: casaburi{at}ucla.edu
See the Related Editorial on Page 547
Dr Casaburi discloses relationships with Inogen, Boehringer-Ingelheim, GlaxoSmithKline, and Regeneron. Mr Hess discloses relationships with the COPD Foundation and Inogen. Dr Porszasz discloses relationships with United Therapeutics, Genentech, and Regeneron. Dr Tal-Singer discloses relationships with GlaxoSmithKline, ENA Respiratory Board on behalf of the COPD Foundation, Teva, ImmunoMet, Vocalis Health, and ENA Respiratory. Dr Ferguson discloses relationships with United Therapeutics, Genentech, and Regeneron. The remaining authors have disclosed no conflicts of interest.
The COPD Foundation provided funds for acquisition of the portable oxygen concentrators. Mr Nick Vannatta of First Class Medical waived the rental charge for the Food and Drug Administration–cleared oxygen concentrator.
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