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Lower max pressure affecting pressure increases
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Rcgop Offline

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Machine: Resmed AirSense 10 autoset
Mask Type: Nasal pillows
Mask Make & Model: AirFit P10
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CPAP Pressure: 6.0 - 10.0 / EPR 2
CPAP Software: SleepyHead

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Sex: Male
Location: Orlando Fl

Post: #1
Lower max pressure affecting pressure increases
Last nightI lowered my max pressure from 16 to 14. My max pressure has never risen above 10 or 11.

The question is: Does the degree of change in pressure depend on the available max limit.

My pressure would not raise above 10 or 11 with the 90 % being in the 9 range. Last night my pressure MAX was 8.88 with a 90% pressure of 8.16.
AHI of 1.1, zero OAs, and split between CAs and HAs.

I am not sure if I am explaining this right but does the pressure change algorithm look the available change allowed.

I am thinking that my pressure change was not as severe as before which is allowed me to sleep better.

HuhDont-knowI 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
07-16-2016 02:29 PM
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DeepBreathing Offline
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Machine: Resmed S9 VPAP Adapt
Mask Type: Full face mask
Mask Make & Model: F&P Simplus
Humidifier: Resmed H5i
CPAP Pressure: EPAP: 9 - 15 PS: 3 - 10
CPAP Software: ResScan SleepyHead

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Sex: Male
Location: Perth, Western Australia

Post: #2
RE: Lower max pressure affecting pressure increases
I don't think changing the maximum setting will cause the machine to operate in a lower pressure band generally. It will go as high as it needs to and you can sometimes see the pressure graph bumping along the maximum. This indicates that it wants to go higher.

On the other hand, there has been some discussion that Resmed machines respond aggressively and can overshoot or "run away" when raising pressure in response to events.

As always with apnea, one night does not constitute a trend. It would be interesting to look at a week's worth of SleepyHead graphs before and after the change to see what's happening over a longer period, and in a bit more detail.

DeepBreathing
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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. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
07-16-2016 07:16 PM
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Rcgop Offline

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Posts: 219
Joined: May 2016

Machine: Resmed AirSense 10 autoset
Mask Type: Nasal pillows
Mask Make & Model: AirFit P10
Humidifier: installed
CPAP Pressure: 6.0 - 10.0 / EPR 2
CPAP Software: SleepyHead

Other Comments:

Sex: Male
Location: Orlando Fl

Post: #3
RE: Lower max pressure affecting pressure increases
If that were the case, there would be no reason to lower the max pressure. Unless the purpose would be solely to stop runaway pressure increases.

HuhDont-knowI 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
07-16-2016 07:21 PM
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DeepBreathing Offline
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Posts: 2,296
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Machine: Resmed S9 VPAP Adapt
Mask Type: Full face mask
Mask Make & Model: F&P Simplus
Humidifier: Resmed H5i
CPAP Pressure: EPAP: 9 - 15 PS: 3 - 10
CPAP Software: ResScan SleepyHead

Other Comments:

Sex: Male
Location: Perth, Western Australia

Post: #4
RE: Lower max pressure affecting pressure increases
(07-16-2016 07:21 PM)Rcgop Wrote:  If that were the case, there would be no reason to lower the max pressure. Unless the purpose would be solely to stop runaway pressure increases.

That's one reason. An Autoset machine should not go higher than the clinical demand but we know anecdotally that sometimes they do. Reasons to set a maximum are: 1) prevent pressure runaway; 2) prevent the pressure going higher than you can tolerate (even if there might be a clinical demand for a higher pressure).

DeepBreathing
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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. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
07-16-2016 07:27 PM
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Rcgop Offline

Advisory Members

Posts: 219
Joined: May 2016

Machine: Resmed AirSense 10 autoset
Mask Type: Nasal pillows
Mask Make & Model: AirFit P10
Humidifier: installed
CPAP Pressure: 6.0 - 10.0 / EPR 2
CPAP Software: SleepyHead

Other Comments:

Sex: Male
Location: Orlando Fl

Post: #5
RE: Lower max pressure affecting pressure increases
That makes sense to me.

Thanks

HuhDont-knowI 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
07-16-2016 07:45 PM
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green wings Online

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Machine: Respironics System One RemStar Pro (460)
Mask Type: Nasal pillows
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CPAP Pressure: 13.0 cm
CPAP Software: SleepyHead

Other Comments: using CPAP since Jan. 2016

Sex: Undisclosed
Location: US

Post: #6
RE: Lower max pressure affecting pressure increases
It's hard to find information on exactly what the pressure response algorithm does in detail. This table from an article on auto CPAP algorithms has some information about it. Based on what it says, the pressure algorithm does not take the maximum pressure setting into account in calculating its response. (aside from not increasing the pressure above the maximum, of course) With ResMed machines, pressure increases are smaller at higher pressures, though. (The same apnea might cause a 2 cm pressure increase at 7 cm but only a 0.5 cm increase at 18 cm.)

I agree with Deep Breathing's suggestion to look at more than one day's data. I have had the same impression as you from looking at my daily graph after changing the max pressure limit.

(07-16-2016 07:21 PM)Rcgop Wrote:  If that were the case, there would be no reason to lower the max pressure. Unless the purpose would be solely to stop runaway pressure increases.

As far as I know, the only reasons to set a maximum pressure value are to keep the pressure from going higher because a) it's not comfortable, b) it has historically caused mask leaks or mouth leaks or c) it's in our nature to want to put on upper limit on something that's happening while we're asleep.
07-17-2016 12:09 PM
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vsheline Online

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Other Comments: Marfan Syndrome, chronic bradycardia, occasional Cheyne-Stokes Respiration

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Post: #7
RE: Lower max pressure affecting pressure increases
Some people have a high pressure threshold, above which they suddenly get severe central sleep apnea. Lowering the Max Pressure below this threshold avoids the central problem, at the cost of possibly getting higher number of obstructive events.

At least a few patients have seen increased intraoccular presssure from CPAP therapy and have limited their Max Pressure for that reason.

In addition, high CPAP treatment pressures have been known to cause dizziness or hearing problems, especially if patients had taken in recent months one of the very many ototoxic (poisonous to the inner ear) prescription or non-prescription meds.
Medicines which are Ototoxic are thoroughly covered in Neil Bauman's third edition of his book Ototoxic Drugs Exposed. An old article on the subject:
http://www.hearnet.com/features/articles/Ototoxic_Drugs_Exposed.pdf

Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.
(This post was last modified: 07-17-2016 02:04 PM by vsheline.)
07-17-2016 01:00 PM
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0rangebear Offline

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Machine: ResMed AirSence 10
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Post: #8
RE: Lower max pressure affecting pressure increases
(07-16-2016 07:21 PM)Rcgop Wrote:  If that were the case, there would be no reason to lower the max pressure. Unless the purpose would be solely to stop runaway pressure increases.

I have the same machine, and have had the similar results. The 90% tracks upward when I raise the upper limit. The lower also seems too have the same effect on the average pressure.

14 day averages
Average Pressure 13.61 13.52 13.37 12.88 12.65 11.26
Min Pressure 13.00 12.80 12.00 11.00 10.00 5.00
Max Pressure 15.40 15.60 15.80 15.60 16.00 15.00
90% Pressure 14.32 14.54 14.88 14.68 15.02 13.92

I have found I have less events when if I keep the 90% bellow 14.60 and the average above 13.50
07-17-2016 04:02 PM
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eseedhouse Online

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Other Comments: Also on supplemental O2 at 3L/min. while sleeping.

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Location: Victoria, British Columbia

Post: #9
RE: Lower max pressure affecting pressure increases
(07-17-2016 12:09 PM)green wings Wrote:  I agree with Deep Breathing's suggestion to look at more than one day's data. I have had the same impression as you from looking at my daily graph after changing the max pressure limit.

I do think it's valuable to look at each day's data, but not to draw conclusions based on a small sample. After awhile you begin to see the patterns and understand how they affect you.

Ed Seedhouse
VA7SDH

I am neither a Doctor, nor any other kind of medical professional.

Actually you know, it is what it isn't.
07-17-2016 06:18 PM
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green wings Online

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Machine: Respironics System One RemStar Pro (460)
Mask Type: Nasal pillows
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CPAP Software: SleepyHead

Other Comments: using CPAP since Jan. 2016

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Location: US

Post: #10
RE: Lower max pressure affecting pressure increases
Okay, some more good reasons to use the max pressure setting. I did not know about any of those except for the central apnea problem.

(07-17-2016 01:00 PM)vsheline Wrote:  Some people have a high pressure threshold, above which they suddenly get severe central sleep apnea. Lowering the Max Pressure below this threshold avoids the central problem, at the cost of possibly getting higher number of obstructive events.

At least a few patients have seen increased intraoccular presssure from CPAP therapy and have limited their Max Pressure for that reason.

In addition, high CPAP treatment pressures have been known to cause dizziness or hearing problems, especially if patients had taken in recent months one of the very many ototoxic (poisonous to the inner ear) prescription or non-prescription meds.
Medicines which are Ototoxic are thoroughly covered in Neil Bauman's third edition of his book Ototoxic Drugs Exposed. An old article on the subject:
http://www.hearnet.com/features/articles/Ototoxic_Drugs_Exposed.pdf
07-17-2016 07:03 PM
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