The Important Relationship Between an Oxygen Flow Meter and Breathing Pattern

Before you buy an oxygen flow meter, there is something to learn about in advance: your breathing pattern can affect the final oxygen dose you receive from your flow meter.

Many patients receiving oxygen therapy aren’t fully aware that various breathing patterns have direct effects on how they set their oxygen flow meter.

Your physician prescribes oxygen at a specific dose, one that is appropriate for your condition. However, even though your doctor has prescribed a set liter flow for you (usually 1–3 liters per minute), many variables affect that liter flow. And some can lead to dramatic shifts in the amount of oxygen you are receiving.

How does this happen? The main problem affecting your therapeutic oxygen level is air dilution.

Therapeutic Oxygen and Air Dilution

First, it is important to note that the air we breathe is not pure oxygen. Only 21% of the air we breathe is made up of oxygen. The rest is made up of nitrogen and some other trace gases. The oxygen in the air is always stable at 21%, so a man-made oxygen concentration system must source anything beyond that.

When we use therapeutic oxygen, we are raising the baseline level of oxygen in the air from 21% to 25%, 40%, or even up to 100%. Here is the reason: During illness and disease, the balance between the oxygen in our bodies and the available oxygen in the atmosphere is thrown off. In the case of pneumonia, portions of the lungs are filled with fluid, so getting enough oxygen into the blood becomes more challenging.

To remain healthy and alive, delivering higher levels of therapeutic oxygen is the only way to get enough into your body when conditions of low blood oxygen (hypoxemia) are present.
However, when more oxygen is introduced into your environment, getting the right concentration depends on your breathing pattern and the available equipment.

How Your Breathing Pattern Dilutes Therapeutic Oxygen

Five main variables affect the amount of oxygen you receive from your oxygen flow meter:

  • Mouth-breathing
  • Breathing rate
  • Breathing depth/speed
  • The interval difference between inhaling and exhaling
  • Oxygen device

If you are using a nasal cannula, breathing through your mouth leads to increased air dilution, which lowers the amount of oxygen that ends up in your lungs. You will still get the same amount of oxygen that is in the air regularly, but the effect will be like decreasing your oxygen flow meter. If mouth-breathing is unavoidable, an oxygen mask can cover both the nose and the mouth, circumventing the mouth-breathing problem.

Educate yourself with our Free Oxygen Therapy Guide

The rate of your breathing also affects therapeutic oxygen flow. If you take in more breaths per minute (anything higher than 20 breaths per minute), you are going to dilute the therapeutic oxygen coming in. On the other hand, if you slow down your breathing, you can effectively stabilize the amount of oxygen you are getting from your oxygen flow meter.

The same idea goes for breathing depth. If you take in a deep breath too quickly, you will draw in more air than oxygen, which decreases your therapeutic oxygen level.

The way to avoid this is to take deep breaths slowly. Doing so will allow you to stabilize the amount of oxygen you are breathing in from the oxygen flow meter.

Additionally, the interval difference between inhalation and exhalation also affects your therapeutic oxygen level. Usually, the ratio between inhalation and exhalation is 1:2, which means for every 1-second inhalation, there is at least a 2-second exhalation that follows. If your inhalation and exhalation intervals are the same (such as a 1-second inhalation and 1-second exhalation), then your therapeutic oxygen level will decrease. However, keeping this ratio closer to 1:2 is the best way to stabilize therapeutic oxygen levels.

The final variable that affects the amount of oxygen you get from your oxygen flow meter is the type of oxygen device you are using. I will discuss this in the next section.

Oxygen Devices and Their Effects on Oxygen Flow Meters

Four commonly-used oxygen devices can affect therapeutic oxygen levels differently and are sensitive to your breathing pattern:

Nasal cannulas are plastic devices that sit inside your nostrils and deliver a low amount of oxygen. These devices are the most comfortable option, but they are sensitive to air dilution.

As discussed above, mouth-breathing bypasses the therapeutic oxygen going into your nostrils and dilutes the air going into your lungs with atmospheric air (at 21% oxygen). To avoid this, the trick with nasal cannulas is to concentrate on breathing through your nose most of the time, but they will work just fine if you are breathing through your mouth slowly and deeply.

Reservoir cannulas look and function just like regular nasal cannulas, but they have a reservoir system that conserves a small volume of oxygen for the next breath. Doing so enriches the initial part of the next breath with oxygen. Reservoir cannulas are still susceptible to mouth-breathing, but the reservoir mitigates some of that air dilution.

Simple masks are plastic face masks that cover your nose and mouth and deliver oxygen from a flow meter. These masks eliminate the mouth-breathing problem and can safely provide a stable amount of therapeutic oxygen. They are, however, still susceptible to the effects of your breathing pattern. The key to using simple masks is to keep your breathing rate slow and also take in deep breaths slowly.

While this next oxygen device is mostly used in acute or emergency situations, the nonrebreather mask is a great option to eliminate the mouth-breathing problem and breathing-pattern variables, particularly when you need a higher concentration of oxygen for a specific medical reason. With these masks, a large reservoir bag fills with oxygen continuously so you can achieve close to pure levels of oxygen. However, you would need an oxygen flow meter that can go as high as 15 liters per minute because this device requires it.

Using pure oxygen can be damaging to your lungs, so you should only use nonrebreather masks, or therapeutic oxygen in general, under the direct supervision of a physician or medical professional.

Final Thoughts

How you breathe, and the oxygen device you choose, affects the oxygen you receive from your oxygen flow meter. Even though you have diligently set your oxygen to 2 liters per minute (or whatever your prescription is), that doesn’t mean you will get precisely 2 liters per minute. As we have seen, there are several variables to watch out for, so you can ensure you are receiving enough oxygen from your device.

Information on this page is for reference and educational purposes only. For more information talk to your doctor or primary care provider.

Page last updated: October 23, 2018


About Ryan Anthony: Ryan Anthony, BS, RRT is a registered respiratory therapist and content writer and medical blogger currently located in Los Angeles, California. As a Respiratory Therapist, he performs a wide range of hospital duties including adult and neonatal intensive care, nitric oxide therapy, high-frequency oscillatory ventilation, conventional mechanical ventilation, noninvasive ventilation, BiPAP, CPAP, intubation assistance, bronchoscopy assistance, cardiopulmonary resuscitation, chest physiotherapy, and nebulizer therapy.

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