Pulse oximeters: Do they actually detect if you have Covid-19 and should you get one?
Finger on the pulse
The most-feared “silent killers” when it comes to diseases used to be those that could stop one’s heart with little prior warning. These days, they’re the Covid-19 variants which have infiltrated into many parts of the world: the South African variant (B.1.351), the UK variant (B.117) and the Indian variant (B.1.617.1).
Malaysia’s health director-general, Tan Sri Dr Noor Hisham Abdullah, says most of those infected with these variants did not display the typical Covid-19 symptoms such as cough or fever. Some do experience joint pain, tiredness and loss of appetite—but many were asymptomatic and did not even lose their sense of smell or taste (two indicators which have been used to detect Covid-19 among those who otherwise felt healthy).
Most worryingly, he confirmed that Covid-19 screening tests for patients with the new variants often came back negative. However, these variants spread quickly to the lungs. Hence, it’s becoming more common to use a pulse oximeter at home to self-monitor oxygen levels.
What is a pulse oximeter and how does it work?
A pulse oximeter is a small, clip-like device that’s most often placed on a fingertip. It uses light beams to estimate the amount of oxygen in the blood without needing to draw a blood sample.
This reading of oxygen saturation level, usually abbreviated to SpO2, is presented as a percentage. In healthy individuals, oxygen saturation levels range between 95 to 100 per cent. However, those with certain health conditions may have lower oxygen saturation levels; your doctor will be able to advise on what’s considered normal for you.
Values under 90 per cent are considered low. Generally, you should seek medical attention if your oxygen saturation level is lower than 95 per cent.
Is it accurate in detecting Covid-19?
Some Covid-19 patients have been known to have significantly reduced pulse oximetry readings, yet no signs of respiratory issues such as shortness of breath. This is known as “silent” or “apathetic” hypoxia. In this case, pulse oximeters can be helpful in detecting a change in your oxygen saturation level that would otherwise go unnoticed. Those who test positive for Covid-19, but have mild symptoms that do not require hospitalisation, may also be asked to self-monitor their oxygen saturation levels to ensure their health condition is stable.
But, the device is not without limitations. It is not a replacement for Covid tests: you should still monitor yourself for other Covid-19 symptoms even if your pulse oximetry reading is normal. You should also ask your GP or a trusted pharmacist to recommend a reliable pulse oximeter. This is because commercial models bought directly from stores or online are most likely not clinically tested to confirm their accuracy, so find out which brands are more reliable. Pulse oximeters are also proven to be less accurate in people with darker skin tones.
The Verdict: There’s no harm in adding a pulse oximeter to your Covid-19 toolkit should you have the budget for it. For now though, it's mostly considered to be an extra precaution, rather than a must-have device.
Tips for getting a more accurate pulse oximetry reading:
- Make sure your hand is warm, relaxed, and held below the level of the heart
- Remove any fingernail polish on the finger that you’re attaching to the pulse oximeter
- Stay still without moving the hand where you’re taking your pulse oximetry reading
With Malaysia recording over 6,000 new Covid-19 cases daily as of late, do be vigilant about personal hygiene and social distancing at all times. We can’t control how others choose to behave, but we can choose to limit our exposure to risks.