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Auto CPAP - why narrow the range?
#1
Does an Auto CPAP deliver the pressure you need, when you need it?

If so, why narrow down the pressure range?
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#2
If the settings are closer to what you actually use, the machine doesn't have to make a large change when an adjustment is needed.

Ex. Suppose the lowest level you sleep well at is 7 cm of pressure. If the machine starts at 5, it needs to increase by 2 cm of pressure. If the machine starts at 6, it only has to increase 1 cm of pressure. Which do you think would be faster?

On the top end, some machines may respond to leaks by increasing the pressure higher than is needed (mine seemed to do so). Setting a maximum pressure will keep it from overshooting erroneously should the mask leak.
                                                                                                                                                                                  
Please organize your SleeyHead screenshots like this.
I'm an epidemiologist, not a medical provider. 
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#3
Low pressure is no use to me, anything below 9 would feel uncomfortable and not getting enough air to breathe, plus wouldn't be getting any effective treatment
More like driving a car, if you drive too slow, this upset other drivers and can cause traffic accidents 
Drive too fast, you might hit the car in the front which driving to the road speed limits
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#4
Some people wake up when large changes of pressure are happening in a short time.

Therefore, narrowing the range is preventing those issues.

Ultimately, the point of CPAP therapy is for people to stay asleep.
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#5
Just for the record, when we talk about "start" pressure, we are referring to ramp start.
When we are talking pressure range, we use "minimum and maximum" term.

It took me almost a year to narrow my pressure to a range that did not wake or disturb my sleep.  Keeping a wide pressure range makes the machine work harder than it has to, especially with minimum pressure.  If it is too far away from your 90% reading, and your airway starts to collapse, the Apap will take longer to reach the optimal pressure needed and may miss events......which equals higher AHI.

Some say the maximum pressure doesn't matter, but it sort of does.  An Apap responds to other events like snores and flow limitation, and will sometimes raise the pressure higher than need be. This can be disruptive to sleep.

As far as "large" leaks go, an Apap may respond by raising the flow to try and maintain pressure. 
If you are experiencing alot of "large" leaks during the night, this may be disruptive to sleep.

If your are looking at SleepyHead, try to set your pressure range at 2cm below and 2cm above your
90% number.  

Some are not bothered by a wide pressure range, but I was.  I could actually set my Apap to 11 min and 11 max and get very good results.  This would be much better than switching to straight Cpap because if I stay in Apap mode even at 11-11, the machine will show me flow limitations and rera's.

Strangely, and it's probably physiological, I like to see the pressure range on the SH graph and not just a straight line, so with a 90% reading of 11, you can see from my profile that I keep a narrow range.

One word on Ramp......if you use it, keep it closer to you minimum pressure.

Hope this makes sense.
OpalRose
Apnea Board Moderator
www.ApneaBoard.com

How to Organize and Post ScreenShots

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#6
Hydrangea, when I looked at Patrol's data yesterday, I made the comment recommending an increase in minimum pressure. The Philips Respironics machines are just too slow to increase pressure, and tend to return too quickly to the minimum pressure to avoid events. My comment was based on what I have seen work well for other users of that machine with similar event rates and types.
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#7
I believe a good minimum pressure setting is key to getting good AHIs as one gets closer to the 90% number. Was wondering why not set it at the 90% number, but that would seem to mean setting the pressure higher than necessary and not take advantage of the APAP. With a CPAP there is no choice and there is only 1 setting that must work. I find that as the minimum pressure gets set higher, the APAP pressure during the night doesn't rise much higher than if I had set the minimum pressure lower. That means the maximum pressure is also less likely to be hit.  

My worry is that as time goes by, the minimum pressure will rise correspondingly - I'm not sure. Say a patient is 40 yrs old and starts out with a minimum setting of 8. What will be the minimum setting when that patient is 80yrs old? Hopefully new medical technology and solutions would have evolved in those 40 yrs to change the way sleep apnea is treated.

edit: Meantime I would want to keep my minimum pressure where it gives me good treatment - low enough AHIs below 1.0 and also low pressure fluctuations that don't go anywhere near my maximum pressure setting (but with sufficient buffer at the top end if for some unusual reason for a particular night I need the upper range).
lots-o-coffee
The doctor says coffee does not affect my tinnitus and it's got lots of antioxidants.... 
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#8
I'll add that in some users higher pressures actually cause more events, particular those susceptible to pressure induced clear airway events.

I am one of those individuals that fortunately can easily tolerate higher pressures, So I set my min at 12 and my max at 25, BUT my pressure stays in a very narrow range (typically around 1cmH2O) and am running a 30 day average of .87 AHI.  The ONLY reason I leave my max high, is that I do not need to limit it.  Most user do.
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#9
Agree with all the comments made so far, especially those indicating that every individual is different. I was originally prescribed a set pressure but felt I could do better. Here is a clip from Sleepyhead showing the progress I've made zeroing in on the best settings for me. You can see as I narrowed the pressure range my AHI went down. For me this worked great but again everyone is different and this may not work at all for others.

[Image: zCpXzpjl.jpg]
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#10
(03-05-2017, 07:46 AM)OpalRose Wrote: Just for the record, when we talk about "start" pressure, we are referring to ramp start.
When we are talking pressure range, we use "minimum and maximum" term.

It took me almost a year to narrow my pressure to a range that did not wake or disturb my sleep.  Keeping a wide pressure range makes the machine work harder than it has to, especially with minimum pressure.  If it is too far away from your 90% reading, and your airway starts to collapse, the Apap will take longer to reach the optimal pressure needed and may miss events......which equals higher AHI.

Some say the maximum pressure doesn't matter, but it sort of does.  An Apap responds to other events like snores and flow limitation, and will sometimes raise the pressure higher than need be. This can be disruptive to sleep.

As far as "large" leaks go, an Apap may respond by raising the flow to try and maintain pressure. 
If you are experiencing alot of "large" leaks during the night, this may be disruptive to sleep.

If your are looking at SleepyHead, try to set your pressure range at 2cm below and 2cm above your
90% number.  

Some are not bothered by a wide pressure range, but I was.  I could actually set my Apap to 11 min and 11 max and get very good results.  This would be much better than switching to straight Cpap because if I stay in Apap mode even at 11-11, the machine will show me flow limitations and rera's.

Strangely, and it's probably physiological, I like to see the pressure range on the SH graph and not just a straight line, so with a 90% reading of 11, you can see from my profile that I keep a narrow range.

One word on Ramp......if you use it, keep it closer to you minimum pressure.  

Hope this makes sense.

I too have taken a year to get things close and worked around my 90% pressure. Then out of desperation I took some advice to set my min and max to 2cm BELOW my 90%. 

Guess what? It seems to be working. Last night .5 AHI over 7.5 hours. That's 3 CAs and 1 hypopnea and 0 OAs. Best sleep too. 

Changing pressure does interrupt my sleep.
Dont-know  I am an accountant so any advice given here is not medical. If I give any financial advice, you can take it to the bank. However, you will have a hard time cashing it in. Okay
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