Selecting a Portable Concentrator

Which Portable Oxygen Concentrator Is Right for You?


Portable Oxygen Concentrators (POCs) have piqued the interest of the oxygen community. Often advertised as an all-in-one solution to home oxygen needs, POCs have drawn the attention of not only people like you who have been prescribed long-term oxygen therapy (LTOT), but also the respiratory therapists, home care providers, and respiratory product manufacturers who routinely work with patients needing oxygen. While POC technology is not at a point where the POC can truly be considered as the only product a person on oxygen needs for therapy, we are headed in that direction. But let me make this very clear – we aren’t there yet.

Perhaps you have seen television commercials advertising POCs. More often than not they promise “independence”, “freedom”, and the ability to perform your activities of daily living without the need for any other equipment. These advertisements tout the POC’s portability, eliminating the need for oxygen cylinders and liquid storage tanks and may claim that the POC can be used during all phases of activity, including sleep. These types of commercials make the POC highly desirable, meaning the advertising department has done a great job.

However, and I cannot stress this enough, it is very important to be educated on the capabilities and limitations of the POC before making a purchase. Television commercials alone will not tell you the whole story. Home care provider associates may not be familiar with your oxygen requirements and whether those requirements can bemet by a certain POC product. The last thing you want to do is to put your money down on a POC that cannot meet your needs. The aim of this article is to give you a basic idea of how a portable oxygen concentrator operates and the differences between the two types of POCs currently on the market: Intermittent Flow POCs and Continuous Flow POCs. My hope is that with this information you will be better equipped to answer the question, “Which POC should I buy?”

Understanding the Operation of a POC

At their most basic function, POCs do not operate all that differently from the stationary concentrator you most likely have in your home right now. The POC, like the stationary concentrator, takes in air from the room – a compound of 78% nitrogen, 21% oxygen and small amounts of other gases – and separates the oxygen from the rest of the air. This oxygen is then delivered to you, typically in concentrations between 87%and 95%–much greater than the 21% you get breathing in just room air. When you are on supplemental oxygen, it is this difference in oxygen percentages that helps to increase the oxygen saturation in your blood.

Stationary concentrators typically deliver their oxygen continuously, meaning flow is always coming out of the machine, at flow settings between 1 and 6 liters per minute (LPM). Current POCs on the market, which are much smaller than stationary concentrators, do not have this range of capability. Some POCs are able to deliver up to 3 LPM of continuous oxygen flow, but a majority of the POCs available are only able to deliver their oxygen intermittently, meaning that all oxygen is delivered in short pulses and only during inhalation. While there are no standard naming conventions that differentiate these types of POCs, for the purpose of this article we will call POCs that only deliver their oxygen intermittently intermittent flow portable oxygen concentrators (IF POCs), and we will call POCs that can deliver both intermittent and continuous flow oxygen continuous flow portable oxygen concentrators (CF POCs).

CF POCs versus IF POCs

The distinction between CF POCs and IF POCs is important, if only because the oxygen production capabilities between these two types of POCs are significantly different. There are four CF POCs on the market, the DeVilbiss iGo, the Invacare SOLO2, the O2 Concepts OxLife Independence (currently undergoing a major revision after OxLife was acquired by O2 Concepts), and the SeQual Eclipse. All four CF POC units are able to produce 3 liters of oxygen per minute, which is equivalent to 3000 milliliters (mL). There are several IF POCs on the market, including the AirSep FreeStyle, the Inogen One, the Inova Labs LifeChoice, the Invacare XPO2, and the Respironics EverGo. Oxygen production capabilities of these IF POC units range from around 450 mL per minute up to 1250 mL per minute.

As you can see by these numbers, current IF POCs are only able to produce, at most, up to about one-third of the oxygen able to be output by CF POCs. It is this difference in production capability that allows IF POCs to be much smaller than their CF POC counterparts. As product size is a major reason why POCs are very appealing to people on LTOT, the manufacturers of IF POCs have made the conscious decision to trade the benefit of greater oxygen production for the benefit of having the device in a lightweight package, making it easier for the device to be portable. CF POCs typically weigh between 15 to 18 pounds and when you add accessories such as power supplies, batteries, and a cart, the device weight can increase by an additional 5 to 10 pounds. Current IF POCs are able to be worn around the shoulder or in a backpack, a result of their smaller size and weight (typically between 4 to 12 pounds). In terms of absolute portability, IF POCs have an advantage.

As mentioned above, the IF POC’s portability advantage over a CF POC is the result of a trade off in functionality benefits. Because the oxygen production capability of an IF POC is limited in comparison to a CF POC, an IF POC simply will not be able to meet the range of oxygen needs that a CF POC can. In the current POC market, one general rule of thumb is that the smaller a POC is, the smaller the number of patients able to be adequately oxygenated on that device is. CF POCs have the advantage of being able to address a wider range of supplemental oxygen needs, simply because they are able to provide significantly more oxygen per minute. This also means that, as an oxygen user’s lung condition deteriorates and their oxygen needs increase, a CF POC can be useful to the patient for a longer period of time.

If you are an LTOT user with very low supplemental oxygen needs, a small-form IF POC may be able to sufficiently meet your oxygen requirements for most or all of your daily needs. However, if you are an oxygen user whose oxygen requirements are 2 to 5 LPM during any of your activities, the smallest IF POCs may not be able to provide you enough oxygen, and there is the possibility that none of the IF POCs will be able to adequately meet your requirements. If your oxygen needs exceed 5 LPM at any of your activities, there is the potential that even the current CF POCs models will not be able to adequately oxygenate you at all activity levels. You must understand your own oxygen requirements and the ability of the POC to meet those requirements before using an IF POC or CF POC. It is highly recommended you discuss the purchase and use of a POC with your clinician and/or respiratorytherapist, as well as taking the unit on a “test drive”, before committing to purchasing.

What to Know When Purchasing a POC

When you decide to purchase a portable oxygen concentrator, you are making a commitment to a piece of technology meant to improve your way of life. As with computers, high definition televisions, and automobiles, you do not want to spend a few thousand dollars of your money on a product that is not compatible with your lifestyle and that will be obsolete in a short time. For this reason it is absolutely imperative that you be the one knowledgeable about the POC that interests you – you cannot simply rely on advertising and home care sales associates to adequately inform you of the best options available for you.

How Do You Make an Educated Decision?

First, while POCs might be advertised as the only oxygen equipment you will ever need, this is not yet true. POCs are still a relatively new product and, as with any type of technology, are subject to occasional operational issues rendering the device unusable. It is recommended to always have a backup oxygen delivery system available, such as a stationary concentrator or liquid portable. Also, many clinicians and respiratory therapists are not yet comfortable with approving POCs for use during sleep. Because your breathing patterns typically become shallower during sleep, there is concern that POCs operating on intermittent flow settings will not properly trigger oxygen delivery. While several manufacturers maintain their products are safe for nocturnal use and promote the ability to change the device sensitivity, many do not recommend POC use during sleep without approval from your doctor first.

Second, know your oxygen requirements. Write down your oxygen needs for rest, activity (like walking, completing daily errands, etc.) and sleep, and share these with your doctor, respiratory therapist, and/or POC sales associate, who can (hopefully) direct you to a product that can meet these needs. In an ideal situation, your POC of choice should be able to provide sufficient oxygen quantities while you are at rest, active, sleeping and/or at higher altitudes. Make certain that the POC you purchase can adequately provide you with enough oxygen to keep your blood oxygen saturation levels in an acceptable range. In order to do this, and in consultation with your medical professional, you should ask to take the POC you are interested in for a “test drive”. If “road testing” the POC proves difficult through one provider, find a provider who will let you try out the equipment.

Third, you must understand that not all POCs are created equal. IF POCs are more easily portable than CF POCs, but they also have a smaller range of patient oxygen requirements that they are able to meet. Additionally, IF POCs (and CF POCs set to operate in their “pulse flow” modes) deliver their oxygen in different quantities.When you use a stationary concentrator, any stationary concentrator, you know for a fact that a 2 LPM setting is 2 LPMof oxygen flow. Far more often than not, a POC set to “2” pulse flow does not mean 2 LPM or equivalent continuous flow oxygen.

For example: When you are on continuous flow oxygen, the volume of oxygen you inhale is dependent on your breath rate. At 2 LPM continuous flow and breathing at 10 BPM, you may get about 67 mL of oxygen per breath, at 20 BPM you will get about 33 mL per breath and at 30 BPM you will get about 16 mL per breath.

However, when set to a pulse flow setting of “2”, the AirSep FreeStyle delivers 18 mL of oxygen per breath, the Inova Labs LifeChoice delivers 25 mL per breath, and the DeVilbiss iGo delivers 33 mL per breath – three different POCs, three different volumes delivered at the same numerical setting. On top of that, while the iGo may deliver the same volume per breath as 2 LPM continuous flow at 20 BPM, this only occurs at 20 BPM, and we all know we do not breathe at the same rate all of the time.

So you can see why it is very important that you know what kind of oxygen volumes a POC is capable of producing. All POC manufacturers provide delivery specifications in their product literature, but these are not always comprehensive. If the POC delivers volumes lower than what you need to maintain oxygen saturations during continuous flow, then that POC likely will not be able to meet your oxygen needs. One other factor to consider is not just howyou can use the POC today, but how you will be able to use the POC in the future. If your lung conditions will deteriorate over time, requiring more supplemental oxygen, you will want to purchase a POC that can meet these future requirements as well – do not limit yourself to a POC that will only be useful as long as your lung condition does not change.

Final Thoughts

Answering the question “What POC should I buy?” is difficult, in part because the question is very specific to the person who is asking it. There is no right answer I or anyone else can provide you without knowing your specific situation and needs. I can say that while no POC is “better” than another, one POC may be a better option for you than another. With this article I hope to have given you some insight into what to be considering when asking yourself the question of what POC is right for you. To further help you understand some of the differences between the currently available POCs, see the chart outlining some specific characteristics of the POCs. All information was taken from product literature and other manufacturer-provided information and should not be considered comprehensive.

Written by Ryan Diesem who is Research Manager at Valley
Inspired Products. Pulmonary Paper thanks him for this very valuable comprehensive article.