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What is Oxygen Liter Flow

Anyone beginning oxygen therapy or learning about a loved one’s oxygen needs will hear health care providers talking about liters per minute (LPM) when referencing an oxygen prescription. A patient’s liters per minute requirement is essential to the success of their oxygen therapy, but unless you know what liter flow is, these discussions will be hard for you to translate. Read on to learn more about liter flow and why it matters to your supplemental oxygen prescription.


If you are just learning about oxygen therapy, you may be confused by some of the

terminology. You hear doctors talking about liter flow and LPM, but what is LPM and how does liter flow affect your oxygen therapy? Thankfully, the answer is not complicated.

Liter flow is the flow of oxygen you receive from your oxygen delivery device. This flow of oxygen is measured in liters per minute, or LPM.[1] Every liter per minute of oxygen increases the percentage of oxygen provided to the patient by about 3-4%.[2] Keep in mind that the percentage of oxygen in our atmosphere, or regular breathing air, is just 21%. With each LPM of supplemental oxygen, the patient receives an additional 3-4% of oxygen, so a patient receiving 3 LPM during oxygen therapy would be breathing air that is approximately 30-33% oxygen. For the majority of people requiring supplemental oxygen therapy, increasing their breathable oxygen to about 30-35% improves their blood oxygen levels, thereby providing therapeutic benefits.[1] Whether you use a compressed oxygen cylinder, a liquid oxygen tank or an oxygen concentrator, your oxygen will be dispensed to you based on the LPM liter flow prescribed to you by your doctor.


If you are interested in using a home oxygen concentrator for your oxygen therapy, you will have some additional questions to ask your doctor. When you begin to discuss home oxygen concentrator liter flows and learn what LPM is to you, it’s important to understand the difference between the two types of oxygen flow delivery: pulse dosing vs. continuous flow oxygen. While both delivery types use LPM prescriptions, they deliver the oxygen in different ways.

o Pulse Dosing: Pulse dose oxygen delivery customizes your oxygen delivery based on your breath rate. Oxygen concentrators that deliver pulse dosing use an oxygen conserver and other technology that senses your breathing to adjust your oxygen dose, or your bolus, and provide oxygen to you on your inhale. The faster or deeper you breathe, the more oxygen will be delivered to you to meet your needs.

o Continuous Flow: Continuous flow oxygen offers the same LPM continuously, regardless of the user’s breathing rate. The oxygen flows identically on your inhale and your exhale, meaning some of that oxygen will be wasted.

Many of the smallest portable oxygen concentrators, like those made by Inogen, provide pulse dosing to offer the most customized oxygen therapy experience for you. Most stationary oxygen concentrators and traditional oxygen tanks provide continuous flow oxygen. When you discuss your LPM and liter flow prescription with your doctor, make sure to ask whether continuous flow or pulse dosing is right for your needs. The answer will have a significant impact on the oxygen delivery device you need to use.


Generally speaking, portable oxygen concentrators typically offer liter flows from 1-6 LPM. Inogen Portable Oxygen Concentrators are able to offer these same portable oxygen concentrator liter flows, along with a variety of other features to improve your life on oxygen. Wondering “What is LPM availability with an Inogen One Portable Oxygen Concentrator?” Take a look.

Inogen One Model : Available LPM Flow Rates

Inogen One G3 : Pulse Dose: 1-5 Settings

Inogen One G4 : Pulse Dose: 1-3 Settings

Inogen One G5 : Pulse Dose: 1-6 Settings

Your prescription will dictate how many flow settings you will need.


[1] Mandal, Dr. Ananya. “Oxygen Therapy Administration.” News Medical, AZoNetwork, 27 Feb. 2019,

[2] “Oxygen Therapy.” PCCS, Pulmonary Critical Care and Sleep Medicine Consultants, 18 Oct. 2011,

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