I was thinking the same and apparently it has to be tuned (though I don’t know how real that claim is from the ENT). One thing to check quickly is to use an App

I was thinking the same and apparently it has to be tuned (though I don’t know how real that claim is from the ENT). One thing to check quickly is to use an Apple Watch or similar device with continuous monitoring and see if you have any low blood ox levels. Pulse ox devices are pretty simple but the ones they give you for testing are the only ones that have passed the FDA regs.