Some notes on COVID-19 and using oximeters
It is comforting to know that whereas the survival rate from COVID infection globally is 97%, more than 99% of COVID victims in Nepal survive. Maybe all those nasty PM 2.5s in the air protect us.
There have been discussions in various offices about the necessity of buying a pulse oximeter so I thought I’d post some notes since although these can be reassuring, they can also fuel anxieties if there is no-one around to interpret readings. Whatever readings you get though, remember that although COVID-19 is an unpleasant disease survival statistics are good unless you are already frail.
The World Health Organisation doesn’t recommend home use of oximeters except in vulnerable people meaning people over the age of 65 and/or people with severe respiratory conditions, diabetes, severe obesity (body mass index over 40), etc.
I understand that some people are reassured by scientific measurement but others can become more anxious and I would suggest not measuring oxygen more than a couple of times a day, plus whenever there is significant breathlessness.
The normal range
for pulse oximetry is 94 – 100%
, although some people with chronic obstructive airways disease (usually caused by smoking cigarettes) function well long-term with a blood oxygen of 86%. The normal range is indeed a range
. If a measurement changes, say from 99% to 95% i.e. within the normal range there is NO cause for concern.
Normal pulse rates are also highly variable.
Some local oximeters have the digital display upside-down compared to the permanent OXIMETER lettering so when first trying it out, 98 looks like 86, which is a rather low reading, and this may worry people.
Oximeter readings are lower in people who are lying down flat.
Blood oxygen naturally falls by up to 3% during sleep and this occurs as much as five times a night even when people are perfectly well. This means that if someone wakes in the night and takes an oximeter reading their oxygen saturation may seem worryingly low. In this case sit up or get up and take another couple of readings. Walking around will probably make you feel better anyway.
Blood oxygen falls when people take exercise but a drop of more than 3% suggests that the lungs are struggling. Repeat the measurement after a few minutes.
People wearing nail varnish / polish will also get low readings, so polish must be removed before taking an oximeter reading.
I believe different oximeters are needed if the blood oxygen of children is to be measured.
Remember to continue being good citizens, wear a proper medical or three-layer cloth mask
, keep socially distant and with the correct precautions we will get through this.
I have compiled these notes from clinical experience and by referring to material in the excellent and peer-reviewed British Medical Journal.
Dr Jane Wilson-Howarth, BSc, MSc, BM, DCH, DCCH, DFSRHC RCO&G, FRCP&S, FBGTHA