Pulse vs. Continuous Flow

When you're first prescribed oxygen by your doctor, you will likely discuss the various options available to fit your needs. One of the first determining factors in starting oxygen therapy is figuring out if you’ll need a pulse or continuous flowing oxygen unit. Perhaps you’ve heard your doctor use the phrase "pulse" and "continuous flow" but do you really understand what it means? How does it correlate with machine settings? What’s the difference between the two? Which one is right for you? Let's explore the differences below:

Liters Per Minute & Flow Rate?

Many patients, once they see "liters per minute" on their prescription, assume their only option is a continuous flowing oxygen concentrator or tank. In reality, both pulse and continuous units use LPM, or liters per minute. LPM actually refers to the flow rate of oxygen you’re prescribed. Flow rates are measured in liters of oxygen flowing through the cannula and past the nasal passages. The vast majority of people are prescribed 2 liters of oxygen per minute.

It’s important to note that your prescription may not tell you whether you need a pulse or continuous flow unit. It’s also imperative to understand that liters per minute does not directly relate to the settings on all oxygen concentrators. Generally, most home or continuous flow units have exact LPM settings. However, most portable or pulse dose units will have a setting ranging from 1 to 8. How much oxygen is released on each setting will differ between each concentrator and each brand. For example, if you are prescribed 2 liters per minute of oxygen and the concentrator you’d like to buy has 1-3 settings there is a chance it may not fit your needs. A setting of 2 on one portable concentrator may only give you half of the oxygen your prescription requires while a different brand concentrator’s setting of 2 could give you too much.

Pulse Units

Pulse does delivery goes by many names including: pulse flow, conserving device, and a puffer. Pulse flow, as the name “puffer” suggests, puffs or pulses air into your nasal passage way, through a cannula, with each breath. This means that with pulse, oxygen is delivered every time you take a breath in.  Should the rate of your breathing increase the oxygen concentrator will react automatically and release another “pulse” of oxygen as needed.

The sophistication of pulse dose delivery is best described as drinking water with a straw; the delivery is more controlled and individualized per need. In juxtaposition, a continuous flow machine is akin to that of drinking out of a water fountain; the delivery is less controlled. Unit’s with pulse flow delivery systems tend to be more energy efficient due to the rest periods between each breath. Rest periods significantly increase the battery life of your unit allowing you to enjoy portable solutions for longer. Another benefit of a pulse dose machine is size. Due to the increased efficiency, units can be made much smaller providing patients with more freedom and mobility.

It’s important to note that each brand has a different pulse dose delivery mechanism. This means the "puff" or "pulse" of oxygen may feel slightly different brand to brand and even unit to unit. Most people cannot tell a noticeable difference but if your current solution is uncomfortable, you may want to experiment with another model.

Another notable difference between pulse and continuous flow oxygen delivery is that pulse dose machines do not deliver oxygen in exact LPM (liters per minute) like that of a continuous flow machine. Like we mentioned above, there is little standardization in the industry when it comes to settings and oxygen output. The setting of 2 on one machine does not mean the same thing as the setting of 2 on another machine. We cannot stress this enough and you should work with your doctor to understand the best settings for your needs.

Is Pulse Flow Right For Me?

To answer this question always start with your doctor. While pulse dose works for many people, there are some medical conditions where it is not an option. If you require oxygen at night, many doctors will recommend a continuous flow machine for nocturnal or night time use. That being said, many patients can still use a pulse dose machine during the day time hours. The reason doctors lean toward continuous flowing for sleep is that shallow and mouth breathers may not trigger the pulse sensor. If no pulse is triggered, some machines will alarm causing patients to wake up frequently throughout the night.

Using an oxygen concentrator with pulse flow technology is a great solution for those with an active or ever-changing lifestyle. If you’re frequently out and about running errands, exercising, traveling, or even if you just enjoy a daily morning walk pulse flow can adjust to your changing breath rates to ensure you’re always getting the oxygen therapy you need.

We always recommend that you try out the unit and delivery systems before purchasing or renting especially if you’re going to be traveling!

Pulse Dose Only Machines:

Continuous Units

Continuous flow, is the most common type of oxygen delivery. Continuous flow continuously flows oxygen at a steady and specified rate. Continuous flow is easiest to understand when you liken it to a water fountain. When you turn on a water fountain, water streams out at a somewhat steady pace. If the water fountain were flowing at 1 liter per minute and you were to drink from said stream the likelihood of you consuming 1 complete liter of water in your singular drink highly unlikely.  The same applies for a continuous flow machine, there will naturally be excess oxygen wasted due to the state of constant oxygen delivery.

If you're concerned about excess oxygen waste or your current machine's settings no longer fit your needs you may want to consider an Oxymizer Pendant. The Oxymizer Pendant is capable of reducing oxygen costs by 75% on a continuous flow machine and is our simplest conserving device, operating without batteries or controls! This oxygen saver also has the capability of increasing your LPM up to 2 whole settings. Having this extra reserve of oxygen allows you to run your concentrator on a lower setting, saving energy, money, and battery life!

It is also important to note that all home or stationary concentrators operate in continuous flow delivery.

Is Continuous Flow Right For Me?

Just like pulse delivery, this question starts with your doctor. While continuous flow machines work for many people, it’s always best to consult your doctor. An oxygen concentrator with continuous flow is a sufficient solution if you lead a more relaxed lifestyle. All at home or stationary concentrators operate in continuous flow delivery. If your activity level is low to moderate and your breathing rate stays relatively consistent throughout the day, a continuous flow machine may be right for you. Continuous flow units are often great solutions for those with sleep apnea or other conditions in which you require oxygen at night.  Like we mentioned above, a continuous flow machine won’t alarm while you’re sleeping if you happen to breathe through your mouth or have shallow breathing.

Continuous Dose Only Machines:

Pulse & Continuous:

Why not both? There are several wonderful machines on the market that offer both pulse and continuous flow in a single machine. These machines offer the most in flexibility as they are great for nocturnal use, use with sleep apnea equipment, and can be used during the day on pulse dose to extend the life of the batteries. Our popular and lightweight SimplyGo concentrator by Respironics features pulse and continuous flow and weighs just 10 pounds with battery!

Pulse & Continuous Flow Units:

Additional Factors to Consider:

One of the most important factors we urge our customers to consider is their lifestyle! Unfortunately, some doctors may not take into account just how you’d like to use your oxygen solution. Below are a list of questions you’ll want to ask yourself and your doctor before selecting your oxygen delivery system and machine!

  • Do I require continuous flow delivery for either nocturnal or daytime use?
  • Do I need to use sleep apnea equipment? (CPAP or BiPAP)
  • What is my required liter flow rate?
  • Do I want/need to use oxygen on the go? Ex: in the car, at the store, etc.
  • How heavy of a concentrator do I want? What can I comfortably carry?
  • How long of a battery life do I need on a daily basis?

When making this important decision it’s best to think of your daily routines and how adding a device with pulse or continuous flow might alter or improve them.

At the end of the day it truly comes down to your personal preference in selecting a pulse or continuous unit. As we discussed above, there are solutions that offer both pulse and continuous flow oxygen delivery systems. If you’re not sure which solution is right for you we suggest consulting your doctor and discussing your lifestyle, prescriptions, and how you’d ideally like to use oxygen.

Updated: February 18, 2020
Published: October 10, 2016

About Danielle Jason: Danielle is extensively trained oxygen specialist and used her oxygen therapy knowledge to write on products from leading manufactures such as Inogen, Respironics, Chart, Invacare and ResMed.

25 thoughts on “Pulse vs. Continuous Flow”

  • Dennis Watkins

    I found the information in this article to be very informative
    and useful.

  • thomas resch

    i have hearing problems so i miss alot sorry

    • Margaret Goodman
      Margaret Goodman April 10, 2018 at 3:27 am

      Please feel free to communicate with us via email at [email protected] or you can use the chat function on our website. Please just let mention in your email or chat that you need to communicate via email or chat only. We will do everything we can to assist you.

  • Mason Shoffner
    Mason Shoffner April 12, 2018 at 8:54 am

    My father has copd and has a continuousl flow oxygen generator upstairs running at 2Lpm for bed time. He also has a small portable pulse flow generator for when he is out and about. My question is, is the pulse flow portable unit good enough for him to use ALL day or would he benefit from having another continuous flow machine downstairs also?

    • Margaret Goodman
      Margaret Goodman April 13, 2018 at 5:41 am

      This is something that you should talk about with your doctor. His needs would be based on what his oxygen levels are at.

    • Jerry

      I have emphasizema and on my sleep army oxygen levels dropped to 85% but they don’t wana pay me to sleep with oxygen sense I have to have to have a bipap

  • glenn boss

    I have a respironics simplygo machine that I bought on craigslist and would like to have it checked for proper function and repaired if necessary. Would you give me an estimate of your cost to work on my machine? How to ship, etc?

    • Margaret Goodman
      Margaret Goodman April 23, 2018 at 5:46 am

      Unfortunately, we are not an authorized repair center for Respironics and therefore can not help in servicing of your machine. You can, however, call Precision Medical Parts at 678-903-3102 and they should be able to assist you.

    • Denny Johnson

      These machines are pretty fool proof. If it runs for a long length of time without an alarm, it's likely working just fine. All they do is pump room air through a filter that diverts larger molecules and directs the oxygen to your tube. When they have an issue, you should get an alarm. When you do get an alarm it likely means the air intake filter should be cleaned or replaced - a simple procedure.

  • Maxim Lestenkof
    Maxim Lestenkof June 27, 2018 at 3:33 pm


  • Phillip Delany

    We live off the grid with our own power system. The energy used by a unit is very important to us. My wife has been on oxygen for a few years now, using bottles at a 3 LPM pulse rate, which worked fine until recently. Now she needs continuous flow. The EverFlo provided our supplier is a real energy hog. Any ideas that may help.

  • Rick Wiley

    we want to travel but my wife needs more than 3l sometimes to walk around...just sitting 3l is ok...this is on cont. does any portable machine do this?

    • Margaret Goodman
      Margaret Goodman January 21, 2019 at 4:20 am

      We would love to help you out. Please give us a call at 888-360-9628, and one of our oxygen specialists would like to talk with you about your specific situation and let you know what your options are. If you prefer email, you can reach us at [email protected]
      We look forward to helping you.

  • Joe

    When on board airplane can the oxygen concentrator be used in pulse mode?

  • Juanita Spurr

    My portable inogen one-g3 sometimes, shows a red warning light saying battery is hot. Do I need to replace the battery

    • Margaret Goodman
      Margaret Goodman February 18, 2019 at 7:25 am

      Sometimes that this is not the battery being hot but the unit itself, trying cleaning off the particle filters and see if that helps. If you still have issues, I would recommend that you contact customer care at 877-303-9289.

  • Rosie Nutter

    my hubby is on oxygen and he is a mouth breather should we keep his oxygen on continuous when we have it on conserve sometimes his o2 drops and we have to put it back on continuous

    • Ed Rodgers

      Hi Rosie,

      I think you should continue with it on continuous but the next visit, discuss this with his doctor. He may want to adjust his oxygen or recommend other options that can work for your husband and his medical needs. Good Luck.

  • Millie Davis

    My husband is on 3 LPM he was on pulse but right now hes on continuous after getting sick we need to find a POC pulse and a continuous 3 at least he loves being outside can you recommend a POC that meets his need with a long battery run time.

  • Lynne

    Danielle --- thank you for this incredibly illuminating articl. That said, still can't decide on a portable. --- MY problem, and although I have a great doctor, he doesn't seem to have a clue about concentrators!


  • Suze

    I use a continuous flow model provided through Medicare. I have central sleep apnea so the continuous flow is necessary. It is very heavy and when I travel it is almost unmanageable. Is there a portable, lighter machine I could use? The machine is an older report I s

    • Sanket Jain

      You may try the SeQual Eclipse 5 portable oxygen concentrator for up to 3 liters per minute (LPM) of continuous flow. Or the Inogen At Home for up to 5 LPM. Though Inogen at Home is a home oxygen concentrator, it is lighter and smaller to carry when you are traveling. Moreover, there is a travel case available for Inogen at Home.

  • Terry Mann

    I have found the best solution for me is to have a G3 pulse (one of the few that can be used on an airline) portable unit with a 6 hr battery and a continuous home unit. Nick has been great with all the units and accessories I have purchased from them.


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