With WA seeing a rise in COVID-19 cases, many of us are concerned about the potential for COVID-19 to cause serious illness in ourselves or loved ones. Having some way to monitor the severity of COVID-19 infection at home may be very helpful. In recent months, there have been discussions around people purchasing pulse oximeters for home monitoring of COVID-19 infection.

In this article Dr Alice Crawford and Dr John Blakey discuss the role of pulse oximetry for people with asthma during the COVID pandemic.

1. What is a pulse oximeter?

A pulse oximeter is a device that measures how much oxygen your blood is carrying, giving you your ‘oxygen saturation’.  Oxygen saturation or “sats” are usually written as SpO2 and they are given as a percentage, to indicate how much oxygen your blood is carrying compared to the maximum it can carry. For example, SpO2 94% would mean that your blood is at 94% of its oxygen carrying capacity. 

Pulse oximeters are usually a small, clip-like device that attaches to a body part, usually around your fingertip.

2. How do they work?

Pulse oximeters (“sats probes”) work by shining beams of red and near-infrared light through the skin, usually through a fingernail. The amounts of these wavelengths of light that are absorbed within your red blood cells is different depending on whether they are carrying oxygen. By measuring the amount of light that is absorbed, a pulse oximeter can get a good estimate of the oxygen saturation.

3. Are they accurate?

The oxygen saturation from a pulse oximeter is reasonably accurate, but due to the way that they work they are susceptible to giving false readings if something affects the light being measured.

Not all pulse oximeters are the same and may have varying degrees of accuracy: not all meet relevant manufacturing standards (e.g. ISO 80601-2-61:2017(en)). For example,  newer smart watches can estimate oxygen saturations, but the accuracy from these devices is limited and should currently not be relied upon for medical monitoring.

Other health conditions can also impact on the readings and need to be considered when assessing your result. For example, someone with a severe lung condition, such as Chronic Obstructive Pulmonary Disease (COPD) may have normally lower levels of oxygen saturation. These people would be directed by their healthcare provider on the oxygen saturation level they need to look out for, to know when to seek further medical help.

This means it is important to take into consideration more information than just the number on the oximeter and to highlight why oximeters should be used under the guidance of your health care provider.

Potential Reasons for Misleading Readings

  • Nail polish or artificial nails
  • Poor circulation
  • Darker skin tones
  • Skin temperature is cool e.g. cold hands
  • Finger probe not sited correctly
  • Excessive movement
  • Insufficient time for accurate reading
  • Irregular heart beat
  • Severe infections
  • Adult device used for children

4. Should I buy one to monitor my asthma?

In short, no. The way that asthma affects the lungs, causes an increase in the work of breathing (wheeziness)first, before causing low oxygen saturation. Low saturations are a very serious sign in people who are profoundly unwell. There is no study evidence to show people who have home oximeters are safer, and there is clear potential to be falsely reassured by normal oxygen levels even when an asthma attack is severe. For more information on symptoms of an asthma emergency visit: https://asthmawa.org.au/emergency/

5. How about for monitoring COVID?

COVID-19 can sometimes lead to low oxygen saturation with relatively minor symptoms. Low oxygen saturations have been shown in large studies to be a good way of recognising people who might deteriorate further from their COVID-19 infection. So, if someone has low oxygen saturations but feels otherwise reasonably well, it would be recommended to go to the emergency department for further assessment.

Some treatments for COVID-19 are only given to people that have low oxygen saturations and need supplemental oxygen. Therefore, knowing that oxygen levels are low can mean someone receives additional medicines that improve outcomes.

These points have led to some people recommending pulse oximeters for home monitoring of COVID-19 infections. It is important that any decision to use home monitoring must be part of a more general plan developed with a health care provider. Monitoring oxygen saturations can give results which can be falsely worrying or falsely reassuring, and it’s important to emphasise that COVID-19 can cause significant illness before oxygen levels drop.

Perhaps most importantly, no study has yet shown that having pulse oximeter monitoring at home improves outcomes, and there is currently no evidence that home oximeter use reduces the number of people who go to intensive care or who die.

Having a pulse oximeter at home therefore could potentially be helpful, but it could also cause anxiety or false reassurance without any clear benefit. Please remember that unlike other viruses like ‘flu’, people with asthma are not more likely to get very sick with COVID-19.

Asthma WA Recommends

  1. Don’t buy a pulse oximeter to monitor your asthma
  2. For some people, such as those living a long way from a hospital or who have additional serious health issues, home pulse oximeter use might possibly be considered for monitoring COVID-19 infection
  3. Any use of home pulse oximeters for COVID-19 should be part of a more general home monitoring process and action plan developed with a doctor
  4. The best ways to protect yourself is to get vaccinated, maintain social distancing and hand hygiene, and ensure your asthma is well controlled.

Please note:
As with all COVID-19 related matters, situations change as new study evidence emerges. We will issue an update if any future robust trial information alters our position.

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