Pulse oximeter: can this device detect COVID-19 in time?

Doctors from different countries evaluate having it at home as a preventive measure against the sudden loss of oxygen, one of the symptoms of a person infected with the SARS-CoV-2 virus.

The pulse oximeter is a small device similar to a clothespin that measures the amount of oxygen saturation in the blood. The reason for its importance is because one of the symptoms of a patient with COVID-19 is precisely the rapid decrease in blood saturation (blood oxygen levels). Different doctors indicate that, if one detects this decrease in time, respiratory difficulties could be better controlled.

Following a report in The New York Times at the end of April on the device, its use began to be evaluated in different countries, while in the United States the sale of this tool soared after the article’s publication.

Early detection of coronavirus

According to Dr. Alejandro Macías from Mexico: «the person may not feel anything, but be could be seriously hypoxic. I have seen people who have 75%, who would need a breathing tube, but the patient is happy, calm. Something happens with this disease that the brain is not able to detect this loss of oxygen».

Fernando Mejía, a doctor specialized in infectiology at Hospital Cayetano Heredia, indicates: “When a patient arrives with an oxygen level below 92%, his organs are clearly beginning to be damaged, the lung and the heart are already being damaged and many people do not perceive that. That is why many times people have been seen who are walking and suddenly collapse”.

The oximeter «allows us to predict the future of the disease a bit,» explains Dr. Ricardo Valenzuela, an emergency physician at the Universidad de Los Andes Clinic in Chile.

«We should have it at home, just as we have a device to measure pressure or thermometers. In the future it will be very convenient for families to have an oximeter» says Dr. Alejandro Macías.

How to use it?

It is placed on the middle finger of the dominant hand with the nail pointing up and the results are read.

  • Healthy people will register saturation levels between 95% to 98%.
  • If the oximeter gives results between 92% to 95%, it is recommended to contact a specialist doctor.
  • When the figure is less than 92%, it is ideal to take the person to a hospital.

Some infographics show that it should be worn on the index finger. However, one study indicated that the highest saturation estimate occurs in the middle finger followed by the thumb. So it is recommended to use the middle finger in its use.

Long fingernails can prevent proper oximeter reading. It is better to trim them. As for nail polish, it can alter the reading of the levels as well, especially the black color, as well as false nails.

Intensive care physician Jesús Valverde recommends using the oximeter twice a day, in the morning and at night «because one can wake up with a good oxygen level, but can also end the day with a bad one. You also have to measure the fingers of both hands, always comparing them, because sometimes there are circulation problems in one hand. The highest value should be taken as a reference.» He commented that «the idea is that there is an adequate temperature in the finger, sometimes when it is very cold it should register a little less, then one should warm the hands a little and put the oximeter on at that moment, thus reducing the probability of the device reading error.»


It can be found for sale in Peruvian online retail stores such as Linio, Lumingo, Hiraoka, Mercado Libre, or Farmacia Universal. Its price ranges from 45 soles to 300 soles depending on the quality.

The infectiologist Fernando Mejía stressed: “I recommend that you try to buy new devices and not very cheap, cheap is always expensive and the important thing is that if you cannot have your own, you can agree with neighbors, relatives, but the important thing is have it so that the person who starts with symptoms can be monitored”.

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