Do You Need A Pulse Oximeter for COVID? (Lung Doctor Explains)

If someone has a reliable pulse oximeter at home and knows how to adequately use it, it can benefit some people at this COVID Pandemic. Having normal oxygen levels can be reassuring, although there is no guarantee that someone won’t have a fast decline in their breathing status. It's quite possible that someone has normal oxygen levels and can quickly progress to deficient oxygen levels, sometimes life-threatening. And there are so many factors that come into play. One is the quality of the pulse oximeter itself. Two, how well the person is using it. Three, various factors that artificially raise or lower the reading of the pulse oximeter, and Most Importantly, the different factors that have to do with the person, such as what underlying medical conditions do they have, do they have a sudden worsening of their illness, do they have a new infection that is changing things.

Another factor to consider is what their oxygen level at baseline is? I have plenty of patients at home who have an oxygen saturation of 90%, which is their baseline; that is the best they get. Some of them have lower oxygen levels than that, and they require supplemental home oxygen. So if someone normally has a baseline, O2 sat of 100%, and they are now reading at 93%, that’s much more concerning than someone who has a baseline of 93%. So that’s another factor to consider. But generally speaking, when I’m on the phone with one of my pulmonary patients, and I’m trying to figure out if I should send them to an ER or urgent care center, I want to know some more things because even if the oxygen level is accurate, it's not the only thing to consider.

When someone with COVID has symptoms, the most common symptom besides fever and cough is shortness of breath. Most but not all people with COVID pneumonia have shortness of breath. Likewise, most but not all people who have low oxygen levels have shortness of breath. But some people with COVID don’t necessarily feel short of breath, despite having COVID pneumonia and having low oxygen levels.

Does that mean you should run out and buy a pulse oximeter?
Maybe, Before you decide on whether or not you are likely to possibly benefit from a pulse oximeter. First, let's understand some more things about them. A pulse oximeter is a device that measures the saturation of oxygen in a person's red blood cells. The oxygen saturation is 100%; that’s the highest number you can get. Most devices will clip onto your finger. They work by measuring the amount of light transmitted or reflected through the skin at two different wavelengths. Then they use mathematical algorithms to estimate the level of oxygen saturation in the blood.

The oxygen readings obtained through an app on a smartphone are not accurate enough to depend upon clinical use. There’s actually been a study done on this that showed that they are unreliable. Even though pulse oximeters are not perfect, they are still much more accurate than smartphone apps. Pulse oximeters are always used in hospitals and sometimes used at home for people with underlying health conditions, especially lung conditions, such as COPD/emphysema. Would it be a good early indicator if somebody has Coronavirus infection?' It's unlikely because low oxygen levels are a relatively late indicator that a person has COVID.

So unless someone is feeling ill or feeling short of breath, the pulse oximeter is unlikely to help that situation. In other words, for most people, if they feel fine, the chances of them having low oxygen levels are highly unlikely. So when it comes to the covid pandemic, the purpose of the pulse oximeter, for most people, is best served when someone is feeling ill and they are deciding on whether or not they should go to the hospital. Keep in mind that they're conditions that can cause falsely low readings, such as dark nail polish, artificial nails, nails that are too long that affect the pulse oximeter placement, cold hands, poor circulation, having high lipids in the blood, room lighting, etc.

If you do buy one, also know that some are better than others. There are tons of companies that make them, and they all have their own algorithms to calculate the number, and some give more accurate reading than others.

Doctor Mike Hansen, MD
Internal Medicine | Pulmonary Disease | Critical Care Medicine
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