As we continue to deal with the evolving COVID-19 situation, medical recommendations are constantly changing. This leads to common medical products and devices becoming scarce seemingly overnight. Just a month ago it was nearly impossible to find thermometers at any store. The past week has put pulse oximeters on the public radar, leading to scarcity and, unfortunately, many pulse oximeter ‘scams.’
What is a Pulse Oximeter?
What is a pulse oximeter? Pulse oximeters are devices that measure the oxygen saturation of the blood. It is usually seen clamped on a finger, as they help determine how well oxygen is being carried to parts of your body (especially parts that are further from your heart). A pulse oximeter works by using light to detect how much oxygen is in your blood.
There are many reasons pulse oximeters are used in hospital settings including monitoring your oxygen levels after surgery, checking if a patient is capable of breathing on their own, and monitoring patients who may have other diseases where it is important to watch oxygen levels. Normal oxygen saturation levels are generally considered about 95 to 100. A pulse oximeter reading lower than 95 starts to raise concern.
Why Doctors are Mentioning Pulse Oximeters
Doctors were initially saying that it was not necessary to buy a pulse oximeter for home use unless there was a pre-existing respiratory condition. As time went on, however, we have learned more and more about COVID-19 and what it is capable of. Most patients who get infected with SARS-CoV-2 (the virus that causes COVID-19) have mild – if any – symptoms, usually recovering without any complications.
Doctors in hospital emergency rooms, however, have started reporting that they have patients coming in with COVID pneumonia who have extremely low oxygen saturation levels. According to the doctors, pneumonia in these patients had been present for a while. They should have had trouble breathing long before they came to the hospital. Most of the patients only came to the hospital because they finally felt short of breath for days after developing a fever or cough (or other symptoms). Generally, when oxygen saturation levels drop below 90%, people feel like they are struggling to breathe. COVID pneumonia, however, does not seem to severely affect our ability to exhale carbon dioxide (CO2), so these patients would not have felt short of breath without a buildup of carbon dioxide.
How to Test with a Pulse Oximeter
This new information is scary, of course. It means that people are getting sick and can be critically ill without even knowing it. Doctors still are not sure why some people get so much sicker than others. Some doctors have said that it might be a good idea to keep a pulse oximeter on hand in case you start developing any symptoms. Other doctors are still not recommending buying one.
A pulse oximeter can help detect if your blood oxygen levels are low, even if you do not feel short of breath. Monitoring your oxygen saturation levels could help provide early detection for respiratory problems related to COVID-19, especially COVID pneumonia. If you have tested positive for the virus, it is recommended that you monitor your oxygen saturation levels for at least two weeks. Two weeks after testing positive for the virus is when pneumonia would be most likely to develop.
The tests used to detect COVID-19 have also shown to give false negatives, meaning that some people are testing negative when they actually have the disease. It can be helpful to monitor your oxygen levels if you test negative but have other symptoms like coughing and/or fever. If you have a pulse oximeter and get a low reading, call your doctor first to avoid overwhelming emergency rooms. There may be other reasons why your reading is low that are not related to COVID-19.
If you have no symptoms of the virus, (coughing, fever) using pulse oximetry readings may not be of much use.
Finding the Right Pulse Oximeter
We sell portable pulse oximeters at our pharmacy, and you may be able to find them online. I have been keeping an eye out for alternatives (and looking for scams!) to see what else is available to the public.
One ‘alternative’ I found is an app that claims to be able to read your oxygen level saturation and heart rate by using the camera and flash on your phone. To see if this app was accurate, I compared its results with a real pulse oximeter. Using the real pulse oximeter, I got consistent readings of 97-98% oxygen saturation and a heart rate of 85-86. I used the app to measure my levels and heart rate 4 times and got one oxygen saturation (SpO2) of 93%, then three consecutive ratings of 99%. My heart rate ranged from 82-83 beats per minute (bpm).
After testing myself, I asked a coworker who had been walking around (read: should have a higher heart rate) to test out the app as well. His results from the app were the same as my most recent readings: SpO2 of 99% and heart rate of 83 bpm. Hmm. His real heart rate had been 102 bpm at the time and his oxygen level was 97% on the real pulse oximeter.
I then found a study that had examined the Pulse Oximeter app in the past. I wanted to see if there was any information about the app online. I found a study published in 2019 that showed the app I was looking at (simply called “Pulse Oximeter”) had been found to be inaccurate. 68 patients in the study were known to have hypoxemia (low blood oxygen levels), and the app was not able to identify a single patient as hypoxic.
More Info on Pulse Oximeters
If you look up pulse oximeters online, you will find a large listing for them all over the internet. If you decide to buy a pulse oximeter, it is important to buy one from a trusted retailer or one that you know is FDA-approved. Phone applications that claim to be able to read your oxygen saturation are likely inaccurate and should be avoided. Make sure you are buying a pulse oximeter that works. If you are not sure, call your doctor and ask for recommendations.
Pulse oximeters can be very useful tools when they are used correctly. This means an FDA-approved device being used according to instructions from the manufacturer or a medical professional. Using a bad pulse oximeter can lead to faulty readings and misinterpreted results.
If you have any questions about pulse oximeters or about this article in general, send me an email. I’m happy to answer any questions or hear anything you have discovered about pulse oximeters during the COVID-19 situation.
And don’t forget that we are currently delivering 7 days a week to Naperville residents. If you’re looking at pulse oximeters or need anything else, give us a call today!
Sources and further reading
https://www.ajemjournal.com/article/S0735-6757(19)30467-X/fulltext
https://www.nytimes.com/2020/04/20/opinion/coronavirus-testing-pneumonia.html
https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/pulse-oximetry
