Be assured, if your 5 pro can easily see your vains and no interferences, under the best circumstances it can give you accurate results. Attached is Blood O2 reading
Above was taken, as I had to attend my local hospital for a minor matter. Hat off to UKs NHS, fabulous service.
In general, watch tends to measure lower values. But it is only an indicative value, importants are trends. If you see 95% or 97%, who cares? But if you normally measure 95% and suddenly see a drop to 80%, you should visit a doctor rather.
I have an apnoa and I see the diference if I use CPAP machine and when I don't use it.
