Adding oxygen

I’m new to the group, I’ve been treated with an APAP for about 10 years. Recently my 10 yr old machine started acting up.
My primary care sent me for a new titration study, which showed the need for an increase in the pressure and low O2 levels. This isn’t really a new thing, but she decided it is time for supplemental O2 with the new PAP. A requirement of the ins was doing a new regular sleep study (kicking myself for not suggesting a split night study) But I could do this one at home. Well I didn’t sleep worth a darn. Got a call this afternoon from the DME setting everything up. Seems the test said I don’t have apnea. She believes what happened was I just never got into a deep enough sleep to measure anything. So, another study. She said all I need to do really is the O2 part. I did say I’d do another full study in the sleep lab if it would get things moving, so I think we are going to do that. Checking on the almighty insurance.
My question is when you get a new machine, do you have to do a sleep study (makes sense to me), how often do you get a new machine? How often on the sleep study? Is it worth it to have a sleep specialist? My primary doc admitted she doesn’t know much about apnea.
I just want to be able to not wake up like I’ve been hit by a mack truck and hopefully not have to take naps during the day. I can’t get anything done for not being able to keep my eyes open.

I’ll try and answer a few of your questions. Most insurers will approve a new machine every 5 years. For some, you have to prove the old one is no longer working. If you had a home test and it was negative, they will probably approve an in lab study. You are correct that it should be a split night test. That way, they can see if your O2 levels are dropping with events and not low due to another issue. Your home care company should be able to download the data from your old machine to see what pressures you need. If it is an Auto PAP, it will give you a good idea of what you may need. If the insurance company will only approve a PSG, they will probably order another AutoPAP machine for you.
As to how often you need a study, if you are doing fine and don’t have any symptoms while on your PAP, there is no rule that you have to have another study. If you are having problems on PAP, I would recommend that you see a sleep MD.