Red blood cells

We seem to have developed a range of new vocabulary since the onset of the Covid-19 global pandemic. Suddenly words such as self-isolate, health modelling and social distancing have become the norm. Some of the medical terminology that’s now filling our social media feeds can be unknown and confusing. A question I’ve seen a few times is, ‘What are oxygen sats?’ so I thought I’d answer it in my #quickquestion series.

Red blood cells carry oxygen around our body. They pick up oxygen molecules when they travel through the lungs and then transport it around the body attached to haemoglobin, which is a protein in the red cell. Our body’s organs and tissues need a steady supply of oxygen for them to function.

Oxygen sats is the short form of oxygen saturation and is a measure of how close blood is to being completely saturated with oxygen. Sats are measured in per cent and the goal is 100 per cent. You might also see oxygen abbreviated to its chemical symbol O2.

Healthy people will have O2 sats close to or at 100 per cent. Once levels drop below 95 per cent, then it can become significant. A one off reading, like most things in medicine, rarely gives the whole picture. Some older people and those with long term lung diseases will function quite normally with sats of 94 per cent but in these cases it has usually fallen gradually over time. A sudden drop to 94 per cent in a person who is usually at 99 per cent, is more concerning.

Doctors assessing patients with Covid-19 have guidelines for the level of oxygen saturation that determines the severity of illness and whether a patient needs admitting to hospital for oxygen therapy and observation. They will take the whole patient into account, including symptoms and past medical history and not just the sats number in order to make a decision about what the next steps should be.

Oxygen levels can be measured accurately with blood taken from the artery of a patient, usually from the wrist, and quickly analysed by a blood gas machine. However, good estimates of oxygen saturation are obtained using pulse oximeters, small devices which use infrared sensors to detect red cells in capillaries. These can quickly be popped on fingers, toes or earlobes and only take a few painless seconds to give a reading. They are available for the general public to buy although they are now in short supply. There are oxygen sats apps too, but with all these things, accuracy can’t be guaranteed and you should always use a device that has been appropriately validated. Inaccurate readings could potentially be harmful, if not life threatening, if they give false reassurance.

You can use the NHS 111 online coronavirus symptom checker for advice on what you should do if you are unwell.

Featured Image: by Arek Socha from Pixabay

There are more answers to questions like these and lots of health information to help you lead a happy and active life in my book Sorted: The Active Woman’s Guide to Health.Published by Bloomsbury and awarded First Place in the Popular Medicine category at the British Medical Association Medical Book Awards 2018.

Disclaimer: I can’t give personal medical advice and as always with health advice, reading something online doesn’t replace seeing your doctor who knows your medical history and can assess you in person.  So, if you are unsure then always seek the opinion of a health care professional. 

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