Blood--Oxygen Levels

I gather it is measured by an "oximeter" which uses a small clip on a finger as its source of information.

But have been unable to establish,yet,what are the correct levels.

On my most recent visit to Hospital the number 84 was mentioned,I am not sure if that is good or bad.

Any information would be gratefully received.

send to:  bladder_cancer@btinternet.com