Oxygen concentrators are medical devices that deliver concentrated oxygen through a nasal cannula (a small tube that can be attached to the nostrils to deliver oxygen) or face mask to ensure a person’s oxygen levels remain in the optimal range, says Christine Kingsley, an advanced practice registered nurse (APRN) and the health and wellness director of the Lung Institute in Manchester, Connecticut. They work by drawing air from the surrounding environment and compressing it through a series of filters to remove nitrogen and other impurities, she adds.
Oxygen concentrators can be stationary or portable and deliver oxygen in a pulse dose, meaning only when the user inhales, or in a continuous flow, which delivers a constant flow of oxygen. Because pulse dose systems make it easier to conserve oxygen and battery life, in the past, most portable models offered exclusively pulse dose oxygen therapy. More recently, however, several portable devices have been designed to offer both pulse dose and continuous flow settings, so people with higher oxygen needs can benefit from the mobility of a machine designed for on-the-go use.
Who Needs a Continuous Flow Portable Oxygen Concentrator?
The American Lung Association lists the following conditions as commonly requiring supplemental oxygen, either in the short or long term:
- COPD (chronic obstructive pulmonary disease)
- Pulmonary fibrosis
- Cystic fibrosis
- Pneumonia
- A severe asthma attack
- Sleep apnea
Health care providers determine prescriptions for oxygen concentrators based on the results of specific tests assessing oxygen needs, such as a six-minute walk test and/or nocturnal oximetry (a test that measures oxygen saturation in the body at night), says Tejaswini Kulkarni, M.D., director of the interstitial lung disease program at the University of Alabama at Birmingham and vice-chair of the interstitial lung disease section of the American College of Chest Physicians.
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Pulse dose oxygen concentrators deliver oxygen with each breath and are generally ideal for treating people who don’t require a high oxygen flow rate, says Dr. Kulkarni. Continuous flow oxygen concentrators, however, deliver a steady flow of oxygen irrespective of the number of breaths being taken by the individual and are prescribed when a person’s prescription requires a higher oxygen flow rate.
If the person requires a high flow of continuous oxygen to maintain adequate oxygen levels, then a pulse device [alone] wouldn’t be adequate, says Corey Kershaw, M.D., associate professor of pulmonary and critical care medicine at the University of Texas Southwestern Medical Center in Dallas.
“A continuous flow requirement [upon] testing of 5 liters, for example, would not equate to 5 liters with pulsed flow,” says Dr. Kershaw. “A higher pulse flow is needed to equal what a person requires via continuous flow. People should know that once their continuous oxygen requirement reaches 5 to 6 liters or higher, they very likely will not be able to meet their oxygen needs with a pulse flow device.”
Therefore, it’s important to make sure you have a clear understanding of your oxygen needs before purchasing a portable oxygen concentrator, as the amount of oxygen per minute a machine can provide is a crucial factor, according to Mike Hess, a respiratory therapist and oxygen therapy advocate in Kalamazoo, Michigan.
“Two liters per minute is a pretty common starting prescription for people with relatively mild to moderate hypoxemia (the clinical term for low oxygen levels) on exertion,” he shares. “If symptoms [worsen], they would need more [oxygen], [which] is common as COPD progresses, as well as in conditions like pulmonary fibrosis.”
A health care provider can determine whether an individual is a good candidate for a portable oxygen concentrator and whether this type of concentrator can provide a continuous flow of oxygen at a sufficient level to fulfill their needs, according to experts.
“Continuous flow fills up some of the upper airways with oxygen, allowing people to get a higher effective dose and to be better able to adapt to changing oxygen needs, such as if you get up and start walking somewhere,” says Hess.
If a person’s oxygen needs are high and they lead an active lifestyle, a continuous flow portable oxygen concentrator may be an ideal choice if the device can meet their oxygen needs.
