Sorry, think our posts crossed. Yes, an oximeter (measures pulse ox, pulse) to have in your purse/in your drawer at home is a good thing though it is not strictly accurate w/ edema, cold and such. 93% is nothing to worry about in and of itself and likely reflects a transient response to an irritant...dust. Have you tried a disposable mask, sold in drug stores?
To put the 93% into perspective, when Larry has a mucus plug, his pulse ox goes into the 80's and occ in the 70's. That is when we focus on moving mucus around and he does not lie down until it is 90-ish. And, BTW, those are also occasions where I have to CHANGE the BiPAP settings (he is on BiPAP most of the time) or he would not be able to get the mucus out (he is not a candidate for the Cough Assist or vest but uses IPAP to sort of breath stack in a nasal mask). And that is one of the many reasons you need access to your settings! Sorry to shout but this drives me crazy. Anyone reading this, if you are on BiPAP, learn how to adjust your settings. It is not illegal, immoral or difficult.
I don't see why you need an MRI based on what you have said, but no, it will not show FTD and they would be doing a chest MRI anyway (but that sounds crazy to me at the moment). A chest x-ray would be recommended if you had signs of acute infection, but I'm not reading any...
You and not the RT should control your settings. Larry uses 3 machines in different settings and I tweak them at least once a week depending on circumstances/events, often increasing something and then dialing it back when he feels better. This is a progressive, unstable disease and the tech is not with you every moment. Having a tech change settings based on the past is like driving using the rear view mirror.