If you have COVID-19 or other lung conditions, such as asthma or chronic obstructive pulmonary disease (COPD), your doctor may recommend that you monitor your oxygen levels at home with a pulse oximeter. A pulse oximeter measures the amount of oxygen in your blood and alerts you when the level drops below what is considered normal. However, pulse oximeters are not always accurate. According to the FDA, several factors can affect accuracy, including poor circulation, skin thickness, smoking, and nail polish. Also, recent reports suggest that the readings may not be accurate if you have darker skin.

What is a pulse oximeter?

A pulse oximeter is a small device that attaches to your finger or earlobe and measures the oxygen saturation of your red blood cells (called SpO2). This handy tool became popular last year to help identify the warning signs of COVID-19. Because the lack of oxygen is a serious symptom of the disease and means that you need to see a doctor.

Many people have ordered a tool online or bought it from a pharmacy to test their oxygen levels at home. However, not all pulse oximeters are created equal. There is a big difference between prescription and over-the-counter (OTC) devices.

Prescription Pulse Oximeter: FDA tested and approved to ensure accuracy. It is often used in healthcare settings, such as a healthcare provider's office or hospital. However, your provider may prescribe a home version.

OTC pulse oximeter: Available online or at pharmacies. It has not been reviewed by the FDA and should not be used for medical purposes.

What factors affect the accuracy of a pulse oximeter reading?

There are several ways to help you get the most accurate readings. To get started, take a look at the factors below that may affect your measurements and adjust accordingly. However, in some cases, these factors may be unavoidable and should be considered in the wider planning of readings and symptoms.

Wearing varnish or artificial nails

A general guideline is that certain nail polish colors and artificial acrylic nails can interfere with reading. A recent study suggests that this may not be the case, but it is recommended that you remove your nail polish or artificial nails to be safe. You can also attach the clip to your earlobe or the polished nail of one of your little fingers.

Transparent light

Bright light, such as direct sunlight, can interfere with the pulse oximeter's light measurement. It is far from the lighting of the river.

Bad rotation or cold hands

If your hands are cold or blood circulation is weak, your fingers can be low. Before restarting the device, massage your hands for 1 to 2 minutes to increase blood flow.

Smoking

If you smoke, the value may be artificially high. This is because smokers have high levels of carbon monoxide in their blood. Carbon monoxide can look like oxygen on a pulse oximeter, so you can overestimate the oxygen content of your results.

Dark skin

A report published in the New England Journal of Medicine found that dangerous false pulse oximeter readings were much more common among blacks than whites.

How to Interpret Pulse Oximeter Readings?

When the measurement is complete, the device displays two numbers: oxygen saturation and heart rate. The number below or next to the SpO2 is the oxygen level, and the number of heart symbols below or next to the heart rate (HR) is the heart rate. According to the American Thoracic Society, most people need oxygen levels above 89% to keep their cells healthy. In other words, if the initial oxygen concentration is 98%, you should see a doctor without waiting for the oxygen concentration to drop below 89%. Fixed oximeters are usually accurate to within 4% of the reading. In other words, if the oxygen level is 92%, it could be as high as 88% or 96%. These numbers are estimates, and looking at the learning process over time will give you a better idea.

It is also important to note that pulse oximeters are most accurate at readings greater than 90%. It is less accurate from 80% to 90% and more stable below 80%.

What are the risks of incorrect pulse oximeter readings?

Improper reading can prevent you from seeking medical help. You may think you're fine because your readings are normal, but in reality, your oxygen levels are dangerously low. Anyone monitoring oxygen levels, especially people of color, should understand that a pulse oximeter is an imperfect device and should not be the sole determining factor in seeking help.

Don't just trust the device, trust your judgment if it feels good or bad. The FDA recommends looking for other symptoms that may indicate low blood oxygen, such as:

• bluish color on the lips, nails, or face
• shortness of breath or shortness of breath
• chest pain or pressure
• increased cough
• anxiety or discomfort

racing or fast pulse

When should I call my healthcare provider?

Remember, some people have no symptoms of hypoxia. Only a medical specialist will know. Contact your healthcare provider if you are unsure of your pulse oximeter readings or if your symptoms worsen. Get tested if you think you have COVID-19 or have been around an infected person. Finally, trust your instincts. They are generally more reliable than battery-powered devices.