11 July 2024

COVID-19 has affected millions of people over the past year and a half. One thing that is quite clear is that the virus attacks the lungs of the infected, causing many to exhibit symptoms of severe pneumonia and, in turn, low blood-oxygen levels.

Besides professional medical equipment, seen in hospitals, used to measure oxygen saturation, in recent months, pulse oximeters and smartwatches with SpO2 tracking functions have become a way for many people to monitor their own health.

Dr. Surasit Issarachai, Haematology (Blood) and Oncology (Cancer) specialist, Bumrungrad International Hospital said that, “The pulse oximeter is not the best way to indicate COVID-19 status. It’s only good at detecting if someone has low oxygen levels in the blood, as it shows hypo oxygenation, or low oxygen concentration.”

“If someone is infected with COVID-19, but the disease is not yet affecting the lungs, the patient may not have low oxygen saturation and could be in the normal range. Once the lungs struggle against more and more damage, however, the oxygen concentration will start to drop. That means, if anybody has low oxygenation, the disease is already quite advanced.”, he added.

Although there are some similarities between a pulse oximeter and a smartwatch with an SpO2 tracker, you cannot rely on its measurement, as there are many factors involved.

Dr. Surasit said that, “A medical grade pulse oximeter is designed to check, at the tip of the finger, with high accuracy. The wristwatch type SpO2 tracking may not have been tested in many circumstances. In some circumstances it cannot be used to replace the standard pulse oximeter. If the patient has poor circulation, partial obstruction of the blood vessels or low blood pressure, pulse oximeter results can be inaccurate”.

Normally, oxygen levels should be above 96% and can vary related to the oxygen source, lung condition and circulation. Someone could have 99% or 100% saturation. Doctor Surasit said that people with chronic diseases, such as obstructive pneumonia, obstructive pulmonary disease, chronic obstructive pulmonary disease (COPD), or other chronic lung diseases, could have a baseline lower than usual, around 93% to 95%

So, the best way to check if you are infected with COVID-19 is still an RT-PCR swab test but, if your home SpO2 reading is lower than 95%, call your healthcare provider.

by Kitipat Chuensukjit