Pressure experiment
Just thought I'd share something I found interesting... A few months ago I experimented with the pressure settings on my CPAP machine. My prescribed setting is 10. I switched my machine to auto mode and set the pressure for 10-13 and was surprised to find that my machine delivered a pressure close to 13 most of the night. But, my AHI never consistently decreased enough for me to feel that having the higher pressure was worth it so I put it back to 10. I was titrated to a pressure of 10 in my sleep study last year.
Fast forward to a few nights ago when I was having trouble sleeping and did not feel like wearing my mask (this is very unusual for me). I decided to turn my machine down from 10 to 9 to see if I could get more comfortable. It turns out I've gotten some of my lowest consistent AHI's on a setting of 9 than I had on 10 or on auto.
As a side-note I do have some problems with CA's when I experience changes in pressure. But, I was surprised to find a pressure of 9 seems to work well for me when the machine went up to 13 in auto mode. Could this be due to the CA's I experience with pressure changes? Sorry, I don't have graphs attached but I thought some people mind find this interesting.
Dagmar
RE: Pressure experiment
It is interesting but as you suspected we need to see some data in the form of graphs. The graphs can be used to see the actual waveforms of your Apnea types and can confirm the efficacy of your settings. They can also be used to confirm your diagnosis. So, I recommend that you install Sleepyhead software and get into the detail of your treatment.
Rich
RE: Pressure experiment
Hi Rich, I have ReScan but have not been bothering (my bad I know) to look at them with my new setting of 9. I did check ResScan when I was on 10-13. I will eventually pull my graphs up but this post is just a general info post because I thought it was interesting.
Dagmar
RE: Pressure experiment
Your original post caught my attention right away. Your case is part of a very interesting subject. Our initial settings don't always correspond to effective treatment. That is why it is important to be an integral part of your own treatment. I wouldn't be surprised if you found out some very interesting things about your condition.
Rich
11-20-2016, 10:35 AM
(This post was last modified: 11-20-2016, 11:00 AM by Crimson Nape.)
RE: Pressure experiment
Like Dagmar, I've had a similar experience but I've been reluctant to publish anything about my experience. I was using a variable pressure of 12-16 with my 95 %tile being 13.2 and an average AHI of 1.6. At those pressures I'm a mouth breather and have to use a chinstrap which is annoying to me. I decided to set my pressure to a constant 8, (just a wild guess) forgo the chinstrap, and see how bad my AHI would climb. To my surprise my AHI dropped to an average of 1.4 for the past 110 days (1.2 for the past 30 days) and my mouth breathing is at a minimum. Ultimately I feel better. I just hope the reporting of my experience doesn't mislead anyone down a false path.
RE: Pressure experiment
Could it be that the lower AHIs at lower pressures are due to a decrease in CA's? Perhaps those of you reporting this phenomenon could indicate what part of your AHI's dropped. Another interesting question is the RDI? At lower pressures did your RERAs also go down? I raised my pressures to decrease RERAs but not too far so as not to increase AHI. Another question for you folks is flow limitation. Is your FL worse at the lower pressures than before?
Happy Pappin'
Never Give In, Never Give Up
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA.
RE: Pressure experiment
sonicboom asks the important question. What is really happening here? Were you reducing CAs and Central Hypopneas? Did your titration result in the correct settings? Did your Doctor interpret your sleep study correctly? I would use the Sleepyhead software to find the answers as it gives a very clear depiction of your waveforms. There are also a number of people on this Forum who have a lot of experience interpreting the waveforms displayed by Sleepyhead.
RE: Pressure experiment
Again, my results are probably atypical. My flow limitations have improved while the ratio of CA's vs OA's vs Hyp seem to stay the same but just fewer of them. My S9 doesn't report RERA's so I have nothing to compare on that parameter. I haven't gotten detailed in analyzing my data. I know I feel better and that's good enough for me. I'm operating on the idiom, "Don't look a gift horse in the mouth".
One side note is my BP is now in the normal range (128/80) which is the first time since the early 1980's.
RE: Pressure experiment
Actually have better results with CPAP, the auto was very close but less variance in pressure suited me. Individual settings for all and the results are in the Sleepyhead software to fine tune your therapy.
1 cmH20 seems like a small drop to achieve my better AHI's but it is a 10% reduction in pressure so I'm pretty happy about it. In my case, I do believe my CA's were throwing off the machine and making it want to increase pressure when I had it in auto mode. 
