What is a pulse oximeter? Should I buy one to monitor COVID-19 at home?

Having a low level of oxygen in the blood is an early sign that COVID-19 is getting worse.

But not everyone has obvious symptoms. For example, some people can have low oxygen levels without feeling short of breath or otherwise feeling unwell.

So some people are buying their own device – a pulse oximeter – to monitor their oxygen levels at home.

Other people routinely receive pulse oximeters as part of their COVID-19 Home Care Package.

The idea is that by monitoring your own oxygen levels at home, you can be reassured that your lungs are adequately oxygenating your blood.

Alternatively, detecting low oxygen levels may indicate that you are in need of urgent medical attention.

So what is a pulse oximeter? And if you can get one, how do you use one to monitor COVID at home?

What is a pulse oximeter? How it works?

A pulse oximeter has been a routine clinical monitor that has been used inside and outside the hospital for many years.

Most of the types that you can buy for home use are designed as a large clothespin that you hang from your fingertips.

One side of the clip projects light through your finger to a sensor on the other side of the clip.

This gives a measure of the color of your blood. Blood carrying more oxygen (oxygenated blood) is a brighter red than deoxygenated blood bluer.

The oximeter interprets the color of the blood (via the amount of light absorbed) to provide a number – the percentage of oxygen in the blood relative to the maximum amount that can be carried.

This percentage is the “oxygen saturation” level. For healthy people, it is 95 percent to 100 percent.

Since the oximeter measures blood from the pulse on your finger, it will also display your heart rate (heart beats per minute).

How are people using them now?

Most people with COVID-19 do not need to be hospitalized.

Services have therefore been set up so that some are follow-up by home health professionals and only come to the hospital if they start to get very sick.

People who are not eligible for this type of home hospital-type monitoring should always monitor their own symptoms at home and see a doctor if necessary.

One of the most important early signs of deterioration in COVID-19 is a drop in the level of oxygen in the blood.

This happens when the lungs become inflamed and less efficient at absorbing oxygen. This can happen even before the person feels particularly sick.

Australian guidelines state that when oxygen saturation levels drop to 92 percent to 94 percent at rest, hospitalization should be considered.

Whether a person should go to the hospital also depends on whether there are other warning signs, such as rapid breathing, old age, lack of full vaccination, if there are any. other medical problems and whether a person has limited social supports.

For children, the number is equal to or less than 95%.

If possible, you should contact your GP or GP, who will advise you according to your personal situation.

If this is not possible, you can call:

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Are the readings accurate?

Oxygen saturation readings are generally very accurate.

However, poor circulation or cold or moving fingers may prevent the device from finding the pulse or may trick the probe into measuring movement as a pulse.

If you have cold fingers or poor circulation, you may need to try another finger or warm your hands by rubbing them together before resuming a reading.

You will also need to stay still and reduce your hand movements while taking a measurement. It might be a challenge to take readings on small children.

Nail polish, especially dark colors, can cause the oximeter to read incorrectly and that is why people are advised to remove it before undergoing general anesthesia in the hospital.

However, nail polish has less effect compared to acrylic nails. So it is best to remove nail polish or acrylic nails from the fingers that you will be using for testing.

What if I have darker skin tone?

The inaccuracy of some pulse oximeters in people with darker skin is more controversial. Darker skin increases the risk of some pulse oximeters due to software issues overestimating oxygen levels.

It’s a problem Australia’s Therapeutic Goods Administration (TGA) is concerned about.

However, he said, he didn’t have the evidence to recommend particular devices.

But with the type of surveillance we see in the community, we consider any discrepancies to be not clinically significant.

The changes are minimal and would not affect the type of care people need.

Observing the readings over a period of hours, or even days, can also provide a better understanding of the severity of the disease.

So, if you have darker skin tone, you can always use a pulse oximeter at home. In the meantime, the manufacturers of pulse oximeters are tackling the software glitches.

So, should I buy one?

If you can afford it, yes. The concern of many healthcare professionals is that, like rapid antigenic testing, oximeters can become difficult to access as the number of cases in the community accelerates.

Just like most households have a thermometer, a simple, low-cost oximeter will allow all of us to monitor our health and call for help if things change.

Pulse oximeters are currently available online and at pharmacies around $ 23 but can cost over $ 100. Expect these prices to increase as supplies become tight.

You can use the same for multiple people in a household, including adults and children.

However, you must clean the oximeter before using it on the next person. You can do this with an antiseptic wipe.

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Are some types better than others?

It is best to get a pulse oximeter that has a “waveform” display so that it can be timed with your pulse and ensure that the oxygen readings are accurate.

Look for one with a set of horizontal bars on the screen as an indicator of the phone’s battery charge.

Or you can buy one that displays a waveform (wavy line to indicate the pulse) on the advertisement or packaging.

Some watches and smartphones also have an oximeter function.

There are emerging evidence some of these devices are accurate enough for home monitoring use.

However, the the evidence is not strong and they are generally not yet licensed for this use.

So if you can get a pulse oximeter that would be better.

Stuart Marshall is Associate Professor and David A. Story is Professor and Head of the Department of Critical Care at the University of Melbourne. This piece first appeared on The conversation.

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