Are Pulse Units Useful for 'High Flow' Patients?

This article was reviewed by Senior Director of Community Engagement and COPD360social Community Manager, Bill Clark, as well as certified staff Respiratory Therapists on February 4, 2020.

Dear COPD Coach,
I use supplemental oxygen, and generally use 4 liters at rest and up to 6 with exertion. I was wondering if it is possible for me to use a pulse flow portable concentrator. If not, is there a continuous unit that would provide enough oxygen? Is there a unit that would allow me to be able to fly on a plane?

-Looking for answers

Dear Looking,

For most "high flow" patients, most often a pulse unit is not an answer. Too often, it is assumed that a pulse unit that has settings of 5 or 6 indicates that this is the liter flow, which is not the case. I’ll explain. Continuous Flow units are rated in Liters per minute. Because pulse units do not put out continuous oxygen, they cannot be measured in liters per minute. Instead, they are classified by size of the individual pulse, how often that pulse can be delivered in a minute, and when the pulse is delivered in the inspiratory (breathing) cycle. More recently, in order to compare the output to continuous flow units, the term “equivalent Liter Flow” is sometimes used.

The numbers on pulse units are settings and are not standardized with other manufacturers. For example, a setting of 1 on a unit might really only be one half liter equivalent, which might mean that at a setting of 5, the unit might only be producing 3 liters equivalent. The other problem when a high flow patient uses a pulse unit is that it is often very easy to "over breathe" the unit, which means you are taking more breathes per minute than the unit is capable of producing. When this occurs, the user will either get a smaller pulse, a pulse with less oxygen, or no pulse at all. In a situation where you exert and become significantly out of breath, the unit may not be able to saturate you – at any setting.

For these reasons, a pulse unit usually is not the answer for a high flow patient. When selecting a portable unit, whether it is a pulse or continuous unit, it is very important that you purchase a unit that has ample reserve capacity to take into account breathlessness as a result of exertion or an exacerbation.

As for your other question, most generally, most airlines will not allow a patient requiring more than 4 liters to fly. There also is not a portable continuous unit available that will provide more than 4 liters. If you do not intend to fly, probably the best alternative for you would be liquid oxygen, but that is often difficult to get in many areas. If you are using compressed oxygen, there are regulators that adjust the flow to the demand, which means the unit increases the liter flow when it detects you are breathing harder.

The important thing to take away from all of this is:

  • Don’t use a unit simply because it is small, light or more convenient.
  • Don’t purchase any unit without first consulting with your pulmonary professional.
  • Purchase a unit that offers sufficient reserve to allow for breathlessness or exacerbations.
  • Make sure you allow yourself the opportunity to try a unit (both at rest and during exertion) to determine if you are being properly saturated.
  • Lastly, selecting the wrong unit can have severe consequences to not only your breathing, but your over-all health. Take the time, do your homework, consult with professionals and then determine what will work best for you.

-The COPD Coach

Coaches Corner is aimed at providing information for individuals with COPD to take to your doctor, and is not in any way intended to be medical advice. If you would like to submit a question to the Coaches Corner email us at We would love to hear your questions and comments. You can address your emails to The COPD Coach.


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  • I am on 2 liters of oxygen I just purchased a gin portable generator that goes to 3 pulse I think that post to his probably equivalent to 2 liters I'll only used it once but this weekend I'm going to do practice a little more
  • I have very severe COPD since age 55 or nine years ago. Don't try and purchase a portable oxygen concentrator on your own. I got ripped off and had to pay a six hundred dollar restocking fee from an untrustworthy dealer. I didn't know the above info until too late.

    I am so much better now , check the reasons why below. I had two pulmonary doctors say my life was over and to give up,. I would not accept that then, I found the right doctor.

    * Per my pulmonary doctors advice:

    Moved to sea level where air is more abundant and cleaner
    Joined pulmonary rehab, still going two times a week
    Lost weight { eat smaller meals more often }
    Joined a gym to build muscle { took 4 years of pulmonary rehab to get to this point }
    Continue reading all I can about the disease
    Keep a positive attitude, and keep moving: gym, tai chi, chair exercise, walking, wii, dance
    Take your medication and nebulizers as prescribed. A pain, I know but I have yet to have an Exerabation after ten years, so I count myself lucky.
    Stay away from sick people
    Have meds delivered by mail, not to expose your self at pharmacy where sick people are
    When you lose your breath STOP, catch your breath by doing deep or pursed lip breathing
    I use a pulse oximeter and check my sats on a regular basis.

    As time goes on If you are lucky like me your life can be close to normal. God speed you in your recovery and getting you back to enjoying life!
  • I would agree that most pulse dose regulators and certainly most POC's do not deliver enough O2 for high flow users. However, the SmartDose technology actually has a sensor that can tell when your breathing becomes more rapid and automatically boosts the bolus to meet your need. Since it's not based on a breaths per minute standard, but responds to your inhaled demand for O2, it not only increases the bolus but also increases the breaths per minute, so it actually works the way we work, instead of trading an increased bolus for a reduced rate of breathing.

    The math involved demonstrates that the SmartDose can actually deliver close to 8LPM when set on 6. The technology is available only to LOX and tank users and is not available in a POC. That's the next step!