More and more of us are buying pulse oximeters, despite the fact that the majority of the sleep clinics in the UK seem to want to keep their patients in blissful ignorance of their actual sleep patterns.
However those of us who want to learn more about their sleep patterns face the problem that we are not trained in how to interpret the results given by these oximeters. My understanding from research data is that the results from pulse oximeters correlate very closely with full polysomnography. If that is right, oximeter users should be able to use their results to indicate accurately whether the pressure they are using is properly controlling their OSA.
To start this discussion I would like to pose the following questions, which are based on my own oximeter (CMS50F). Obviously there may be some other machines which give more, or better, information. If so, details here would greatly assist other users and potential users.
1. What is Basal SpO2(%) and is it significant?
2. My oximeter is pre-set with a "Desaturation Criteria Level" of 88%. What is the significance of this figure, and should I alter it up or down?
3.How low should the "Average low Sp02 %" be, before it is considered abnormal?
4. Is the "Average low Sp02 % < 88%" more, or less, important than the overall average?
5. My oximeter results show %Sp02 levels, and number of events, in bands of 5 i.e. 99-95, 94 - 90 and so on , with the number of events in each band. Should we be aiming not to go below 90 at all, or is the threshold level lower?
6. Is the time in each band significant, and if so what should we look for to show good OSA control?
7. Which overnight pulse levels are considered abnormal?
8. Can the oximeter results be converted into AHIs and if so how?
My apologies for setting out formal questions in this way, but I hope that Rock, and other members, will be able to give expert guidance on these points and others, to assist us all.
We would all benefit if we could understand :
a) the default settings to use
b) which readings indicate good OSA control
c) which readings are considered abnormal / undesirable