How to know when you need a hospital for Covid-19

Explained: What a pulse oximeter is and how it works

15 July 2020 - 09:50 By Tanya Farber
Don't wait: if your chest is sore and you're breathless, seek help.
Don't wait: if your chest is sore and you're breathless, seek help.
Image: Jozef Polc/123rf.com

One of SA's top Covid-19 experts has advised South Africans to “seek help immediately” if they have chest pains and shortness of breath.

“The main symptoms of low oxygen are chest pain and difficulty with breathing,” explains Professor Shabir Madhi, who is on the Covid-19 advisory council to the department of health and is head of the vaccine trials in the country.

He adds that “dizziness” follows as one fails to get enough oxygen to the brain.

He said people should “seek assistance immediately” if they are experiencing “chest pains, shortness of breath, lightheadedness or confusion”, as these are all “telltale signs that your oxygen levels are not adequate”.

Rapid breathing is also a sign.

“If you are taking more than 20 breaths per minute, then you need to receive oxygen,” he told TimesLIVE.

He said it is “difficult to quantify” if many South Africans are failing to seek help when they should, but suspected that “some are delaying seeking care because they’re too afraid of what might happen”.

Across the globe, between 12% to 14% of those who are hospitalised lose their lives and, says Prof Madhi, “South Africa is in the same ballpark figures of what has been observed in other countries”.

Apart from monitoring these symptoms, another way to check oxygen levels is with a pulse oximeter, but these are not readily available to the public in South Africa.

“A pulse oximeter is good to have but they aren't readily available,” said Madhi. “It’s a medical device so very few pharmacists will have it. But, the symptoms on their own will tell you if you need oxygen.”

It’s a small device that clips onto your finger and measures your oxygen saturation levels, and outside of hospitals, one is most likely to see them in an ambulance or a nursing home.

You need to “make sure your hands are warm” while using one, says Madhi.

Nail polish can also interfere with the readings, so the device should be used without any.

“Your saturation should be above 95,” says Prof Madhi, “if it is under 93 you need to get oxygen.”

While the public may also attempt to measure their own oxygen with smartphone apps or fitness trackers, a British general practitioner, Ann Robinson told The Guardian, “There is no evidence to say that smartphone apps or fitness trackers are accurate enough for this purpose.”

In a small percentage of Covid-19 cases, a person can suffer from what’s known as silent hypoxia — where there is no way of knowing that oxygen levels have dropped to very dangerous levels.

Wits University's Professor Shabir Madhi.
Wits University's Professor Shabir Madhi.
Image: Supplied/Wits

This was first reported in Chinese studies but there was no indication of how commonly this occurs.

Cases then showed up in Europe and the UK.

A letter to the British Journal of Anaesthesia suggests that silent hypoxaemia could result from one’s oxygen and carbon dioxide being low, because if only your oxygen is low, it is high blood carbon dioxide that usually causes breathlessness.

The WHO advises that if you have minor symptoms, such as only a slight cough or a mild fever, “there is generally no need to seek medical care”. It advises such people to stay at home, monitor their symptoms, and follow national guidance on self-isolation.

The WHO advises that people get medical attention immediately if they have any breathing difficulties or pain or pressure in the chest.


X