Hey, Rach. Did you check your oxygen saturation while you were walking?

O2 saturation doesn't tell the whole story. It's a good indicator but arterial blood gas, along with a clinical exam and O2 sats is the best way to tell.

How is your pulse? Is it high while you are at 99%? That would indicate that the heart is working harder to get you that 99%.

I very much doubt it is a placebo effect!

Just use it when you need it!!!

Annie