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Abstract
Background: Supplemental oxygen is designed to raise alveolar oxygen partial pressure (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 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 three OTC POCs, an FDA-cleared POC and continuous flow oxygen from a compressed oxygen tank. End-tidal PO2, a surrogate of alveolar PO2, was determined at each of each device’s flow settings at three metabolic rates.
Results: Continuous flow tank oxygen yielded a linear end-tidal PO2 increase as flow increased, with progressively lower slope of increase for higher metabolic rate. The prescription POC device yielded similar PO2 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 PO2 elevation that failed to increase as flow setting was incremented. A second OTC POC produced only minimal PO2 elevation. A third OTC POC, a pulsed-dose device, produced meaningful PO2 increases, though not as great as the prescription device.
Conclusion: Only one of three OTC POCs tested was potentially of use by patients requiring ambulatory oxygen. Physicians and respiratory care practitioners should inform patients requiring portable oxygen that over-the-counter 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
- Corresponding Author:
Richard Casaburi, PhD, MD, Rehabilitation Clinical Trials Center, The Lundquist Institute at Harbor UCLA Medical Center, CDCRC Building 1124 W. Carson St. Torrance, CA 90502 casaburi{at}ucla.edu
- Received August 16, 2022.
- Accepted November 15, 2022.
- Copyright © 2022 by Daedalus Enterprises
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