The major downside to CPAP therapy is that it can take some trial and error: your doctor may need to change the prescribed pressure a few times so that you use the most effective and comfortable setting but after that they are done with us. I have had a cpap for 20 years and have found the interaction with sleep medicine doctors to be lacking. Thanks to the new advancements in computer chip usage you can take more control over treatment plan. Over time, we have health changes, changes in medications, new pains or operations and over all changes in life all affect sleep. I was having huge problems with worse pain and increasing pain medication after I got the sleep program OSCAR and started downloading the sim card from the cpap and learned just what it is showing me. I then had to buy a O2 monitor that had an alarm to wake me up if my O2 dropped below a set point. When we go to a doctor and try to explain we are feeling worse after that medication change they tend to say keep taking it will go away. Walk in with the charts of before the change and after reading the hard data they start talking. In my case the stopping the new pills that had my O2 dropping to 74% was back to 90% drops in two days and I started to feeling much better. Have not taken those pain medications since and am now working with a ENT to fix issues with my nose and TMJ that would have never been addressed. But if you are having to battle the cpap and your doctor and sleep doctor are not helping find a different sleep doctor. Good for you wanting to know what those numbers mean.Source: https://www.talkaboutsleep.com/sleep-apnea/