Low levels of oxygen in the blood could be a sign that your Covid infection is getting worse — here’s how a pulse oximeter could help monitor your symptoms before they spiral.
Worried your COVID-19 symptoms are getting worse? Low levels of oxygen in the blood are often an early warning sign that a Covid infection could be getting worse.
But as some people don’t always experience obvious Covid symptoms, testing the oxygen levels of the blood can be an effective way to monitor any worsening signs of the virus.
How do you test your oxygen levels?
A pulse oximeter is a small portable device that’s placed on the finger to measure how much oxygen there is in the bloodstream. It's a fast, simple way to detect this information without using a needle to take a blood sample.
The idea is that by monitoring your oxygen levels at home, you’ll know that your lungs are oxygenating your blood. If the oxygen levels are too low, this could also indicate that you need urgent medical attention.
An early sign of worsening Covid is a fall in the levels of oxygen in the blood. Oxygen levels fall when the lungs become inflamed, which means they aren’t able to absorb enough oxygen, which can also make it much harder to breathe.
Usually low blood oxygen levels cause symptoms like fatigue or shortness of breath, but with COVID-19, you may not experience these symptoms from a low oxygen level. That’s why it’s important to monitor your levels before the infection gets worse, and to help you understand when and if you require medical assistance.
How does a pulse oximeter work?
A pulse oximeter measures blood oxygen saturation and pulse rate. It has a light that shines through the skin and a sensor that measures the colour of the blood — when there’s more oxygen in the blood it’s a brighter red. De-oxygenated blood is a bluer colour.
The colour of the blood determines how much oxygen there is in the blood. The oximeter is able to interpret the colour of the blood (via the amount of light the device absorbs) to generate a number. This is the percentage of oxygen in the blood — or “oxygen saturation” level — compared to the maximum amount that can be carried. A normal saturation level is between 95% to 100% for a healthy person breathing at rest. Anything below that could be a cause for concern.
According to Australian guidelines, anyone with Covid and a saturation level between 92% and 94% at rest is a sign of moderate disease. Anything less than 93% is a concern and requires medical attention.
Other warning signs that someone might need to go to hospital include rapid breathing, older age, or other existing medical problems. Unvaccinated people are also more at risk of developing more serious complications.
How do you use a pulse oximeter?
Make sure your your nail is facing up and that you have warm, clean, dry hands. You must also remove any nail polish or false nails as these can interfere with the device.
Sit in an upright position, then give your finger a wiggle to get the blood flowing.
Place the pulse oximeter clip on your fingertip with your palm facing down — it clips on like a large peg — and turn it on. The screen should be facing up so you can read the results.
Breathe normally and steadily, taking care to keep your finger still, then wait for the results.
It will generate both oxygen levels and pulse rate results after a minute or so. If results aren’t showing, take a few breaths and try the device on a different finger instead.
You may need to take readings twice a day, during exercise, or anytime your symptoms get worse. It’s a good idea to take notes so you have a record of your results to show your doctor.
If your reading is under 95% then you’ll need more frequent check ups with your GP, or it could even mean that you might need hospital care.
It’s also worth bearing in mind that certain preexisting health conditions, like COPD, may mean that your oxygen levels are always lower than 95%. Check with your doctor which oxygen number you should expect when using your pulse oximeter, and when you need to call for help.
It’s also important to watch for any changes in your symptoms, and contact your doctor if your symptoms worsen or if you do not feel any better.
Should I buy a pulse oximeter?
People at risk, such as those who are over 65, pregnant, immunocompromised or Indigenous, or people with pre-existing heart or respiratory conditions, will most likely be advised by their doctor to have a pulse oximeter to monitor for symptoms, as they fall into the high risk category of developing serious symptoms from Covid.
But even if you’re otherwise fit and healthy, it’s a good idea to have one at home, just like you would a thermometer, so you can check any signs of worsening symptoms yourself. That way you can spot any changes early and act on symptoms fast, before any further complications develop.
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