Wanting to understand pressure range

[AMK]

I started cpap on 2/10/15. I started out with a pressure of 8 and asked if my doctor's office would switch that to apap. They chose a range of 5-9. I have seen hints on this board about it being bad if the low pressure is set too low but I can't find any explanation for that. Can anyone direct me to that information, or explain it? Thank you.

[Huh?]

Many people, myself included, feel like they are suffocating if the pressure is below 6 or 7.

asked if my doctor's office would switch that to apap

You left out some important information: Why did you ask for the change?

(And why aren't you making the changes yourself?)

[OkyDoky]

One point of discussion is that for some people the lower pressures especially with ramp can feel suffocating. Not that you would, it just makes you feel that your not getting enough air.
Second point, the lower number is most important in APAP it is the constant pressure with the upper number covering apneas that for some reason need more pressure to control. I'm a little puzzled that you were on a straight CPAP of 8 and now a range starting at 5. It might be what you need but without looking at your data, I would wonder.
Do you have Sleepyhead and are you looking at your data?

[AMK]

The reason I asked for a range instead of just 8 is that during my sleep study, I had 40 events per hour but just during REM sleep. So the pressure of 8 seemed to just be necessary during REM. I was waking up during the night feeling blasted by air and I wanted to experiment. I admit that on 5-9 now I wake up more exhausted than before I had cpap, but I think that's due to having a mask that leaks (note it leaks tiny amounts, just enough to hit my eyes, not enough to show up as leaks in my "myAir Dashboard"). I'm still trying to sort all this out with very little help from the doctor or DME. I'm only having about 1 event per hour right now...supposedly my treatment is excellent.

I use SleepyHead. It looks like after ramping, my pressure never drops below 7 the entire night, so I'm not sure the 5 setting is hurting because I'm never there.

[Julie]

It can hurt because if you do have an event at a higher pressure, the machine has to take time to reach that pressure and may well not do so in time. So you'd be better off with a range of e.g. 7 to e.g. 12 or 15.

[Sleeprider]

One objective in setting minimum pressure to to set it at a level that prevent most flow limitations, snores and other precursors to apnea. This often prevents hypopnea and OA itself, and when the machine detects a condition requiring higher pressure, it can respond a bit faster, and with less disruptive fluctuation. In many cases AHI can be reduced by increasing the minimum pressure a bit. It really takes a good look at the detail data to see if that opportunity exists. Most of the time where snores and flow limitations and hypopneas are occurring, and increase in pressure will reduce those events, and even reduce the OA events that slip through.

One way to think of it is, a machine set wide open (4-20) will usually allow a lot of events to occur as it continually seeks to find the lowest possible pressure before the next FL or Snore occurs. A machine setup with the minimum pressure near the mean or median pressure requirement, stops much of that, while the pressure increases can effectively treat apnea from REM or sleeping position. A machine setup at the 90-95 percentile will run basically like a CPAP.

[yaconsult]

I don't get it! Why would they provide the latest and greatest of machines that is capable of sensing and adjusting to your needs dynamically throughout the night, and then set it to operate in fixed pressure mode or in a very restrictive range?!

[Julie]

Because while MDs know about apnea, they don't necessarily understand the machines well and take the conservative (if not lazy... leave that to the DME's?) route when it comes to settings... ignoring what the study recommended. It's life, lousy as it is, so that's why the forum's a great place to hang out.

[Jay Aitchsee]

I don't get it! Why would they provide the latest and greatest of machines that is capable of sensing and adjusting to your needs dynamically throughout the night, and then set it to operate in fixed pressure mode or in a very restrictive range?!

Although APAP machines are capable of operating over a wide range of pressures, sometimes pressure swings can be disturbing to the patient. See Wulfman's posts (an example below) for multiple discussions on the subjuect. Some people believe better APAP therapy results when the machine is set to a narrower range.

I have similar issues with using an APAP in a range of pressures. When I have used it and even when I don't, I have very few apneas.....sometimes none to maybe 10 or 15 in a month, I have very few/occasional flow limitations, a few hypopneas and a few snores. Virtually NONE of the "predictors" (snores or flow limitations) occur before what few apneas I do have. So, for me, the pressures chasing a few snores, a few flow limitations and the periodic pressure "bumps" are not worth having my sleep disrupted.
When I was about to begin my therapy, I had read about the Autos chasing snores......and since I was a horrendous snorer at that time, I decided to just go with a straight pressure data-capable machine to start with and then somewhere down the road look into getting an Auto for a secondary/backup machine.......which is what I did.

[AMK]

How do you know your sleep is disrupted by the pressure changes? By being awakened by them?

[Jay Aitchsee]

How do you know your sleep is disrupted by the pressure changes? By being awakened by them?

Well, yes, but sometimes you might not know you are being disturbed, though close examination of the flow rate wave could indicate disturbances. Generally, the best indicator of how well the therapy is working after AHI is reasonably controlled is by how you feel.

[Sleeprider]

If you have a treated AHI that is very good (less than 2.0) and continue to wake up tired and low energy, it's possible you experienced arousals that disrupted your sleep. Because an arousal may only pull you to a different stage of sleep, you may not have a recollection of the event. In those cases, therapy looks fine, but the person is still not having good sleep, so you might see us recommend a fixed pressure trial. Happens fairly often. There may be other reasons that sleep is disrupted, or a person feels tired, but at least a trial of fixed pressure can determine if they need to look elsewhere.

[AMK]

It looks to me like my flow limitations got worse once I was switched to 5-9. I see a lot more spiking in that graph than when the pressure was a steady 8.

[palerider]

I don't get it! Why would they provide the latest and greatest of machines that is capable of sensing and adjusting to your needs dynamically throughout the night, and then set it to operate in fixed pressure mode or in a very restrictive range?!

ignorance, stupidity, subconscious desire for patient to fail, take your pick.

[palerider]

It looks to me like my flow limitations got worse once I was switched to 5-9. I see a lot more spiking in that graph than when the pressure was a steady 8.

if you're going to have flow limitations, then typically, lower pressure = more flow limitations. the usual remedy to flow limitations is more pressure.

change your min pressure to 7... going to 5 was stupid of them.