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Bipap question
#11
(05-17-2014, 01:44 PM)retired_guy Wrote: You might want to discuss this with your sleep docs, but I'm thinking you might want to slowly, very slowly begin adjusting the max pressures downward. To begin with maybe something like a min of 11 and a max of 18.
...

(05-17-2014, 01:29 PM)readyforsleep Wrote: Thanks for your ideas. Not sure I understand. Are you saying that
Just because the autopap can go up to 20, it doesn't necessarily mean
I need a pressure of 20? I never even considered that possibility. I do have
a followup visit with the doctor in June. I'll see what she suggests then. She
made a point of telling me not to change anything before my next visit. Wonder
why??
...

(05-17-2014, 12:31 PM)retired_guy Wrote: ... A lower leak rate might mean the machine would not have to work so hard and consequently not run quite as high a pressure which makes the leak rate go up.

Hi retired_guy,

I think it is a common misconception that high unintentional Leak will cause the machine to increase the mask pressure. Even a moderately high unintentional Leak of 20 or 30, for example, does not cause the machine to raise the mask pressure. In the presence of Leak the machine's algorithms increase the airflow the machine is producing but only enough to compensate for the unintentional mask leaking, so as to maintain the machine's target mask pressure.

It is important, though, for the hose type to be set correctly to inform the machine what diameter and length of hose is being used. As long as it knows the hose type, it's algorithm for calculating the pressure loss through the hose will be accurate and therefore it will will be able to accurately maintaim the mask pressure at its target pressure, especially if the leaking is steady and doesn't fluctuate quickly. (However, the more quickly the leaking is varying, the less accurate the machine's treatment will be.)

That the pressure is maxing out is not, in itself, any reason to consider lowering the Max Pressure setting.

Reasons to consider lowering the Max Pressure setting would include excessive centrals if seen in the machine's reported data to begin mostly at high pressures (some people see excessive centrals at high pressures but most do not), inner ear problems caused by high pressures (hearing loss, ringing or dizziness), air and mucus from nasal cavity leaking from tear ducts after being pushed into eye cavity (full face mask may help prevent this), excessive swallowing of air causing uncomfortable bloating, or the pressure being too high for a new PAPer, making it impossible to sleep or start treatment. Or recent nasal surgery (normally CPAP treatment would be stopped, per surgeon's orders, for weeks or longer after surgery). Or a previous medical history of spontaneous pneumothorax (collapsed lung, just from coughing or other normal activity).

Hi readyforsleep,

As retired_guy recommended, it is important to keep Leak low. Many members have reported that when Leaks have been reduced their treatment has become much more effective.

Your doctor wants to see several weeks of data with the machine on wide settings, so he/she can form an informed opinion on how to proceed.

The machine is raising the mask pressure in order to minimize snore, Flow Limitation (upper airway partial collapse/resistance), hypopneas and obstructive apneas. In other words, obstructive events are causing the machine to raise its pressure to 20, which is very high, especially since you have turned off EPR (for good reason, in your case).

One reason to consider getting a bi-level machine is those generally allow a higher setting for Max Pressure, usually a max of 25 instead of 20. But in your case, because you may be susceptible to centrals, you may find that above a certain pressure your centrals will increase, so do keep a lookout for that and keep your doctor informed.

Regarding centrals, one small study reported that about 15% of CPAP patients experienced high rates of CPAP-induced central apneas. In about half of this 15%, after several months or longer of therapy the frequency of centrals gradually decreased to an acceptably small amount. I think the other half of the 15%, the cases which did not go away on their own, probably could have been treated well using Adaptive Servo Ventilation (ASV) therapy using an ASV machine, which is a more expensive machine than a standard bi-level machine.

The most common reason to change to a bi-level machine is to make high pressures more comfortable by increasing the pressure difference between inhale and exhale (especially when the pressures get up to 15 or higher), but this might not apply in your case because this may cause excessive amount of central apneas to occur.

In your case, perhaps best would be to try to lower the amount of pressure your machine needs to use. Rather than lowering the Max Pressure setting (that is, unless you need to because of one of the reasons listed above for retired_guy), I suggest you take precautions to stay off your back while sleeping.

Obstructive Sleep Apnea is usually highly positional, with the worst position usually being flat on your back.

Some put on a small knapsack when they are ready to sleep. I wear a snug teeshirt with a tennis ball in a pocket sewn right between my shoulder blades, so that when I roll onto my back while asleep I wake up just enough to roll over some more, to my other side.

Take care,
--- Vaughn
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.
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#12
Thank you Vsheline. What you explained makes alot of
sense. As far as I know I have never slept on my back. I will
continue to work my leaks -and will leave my pressure alone. I
look forward to the day when
I have a process to consistently have my leaks under control.
2010 sleep study 63 AHI, 2014 3.0
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#13
Can you give us the breakdown of the AHI? How many OA, Hypopneas, & CA's?
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#14
Bama Rambler, The majority of my AHI is OA each night.

Vshline - you are right. I caught myself on my
back last night. Tennis ball tonight.
2010 sleep study 63 AHI, 2014 3.0
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#15
Since the majority of your apneas are obstructive, you might want to raise the min pressure up a bit and see if that helps. Keep an eye on the CA's to make sure they don't take a jump.

It could be that your min pressure is a bit too low and once the apneas start the pressure has to raise more that might be required if the min pressure were a little higher. I'd probably raise it 1cmH2O and see what that does for a few days.
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#16
Thanks
2010 sleep study 63 AHI, 2014 3.0
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#17
My sleep doctor just called (I had called 2 weeks ago) and she
okayed upping my pressure. I'll start at 13 for a couple days see
what changes and go up from there. Too many events going
on here...
2010 sleep study 63 AHI, 2014 3.0
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#18
Keep us informed about what happens, especially the breakdown of the AHI.
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#19
Too early to give any data on my 95% pressure number. As my
low pressure number increases I am experiencing gas issues so
I have had to backtrack a bit from 14 to 13.4. Think I'll
stay at 13 for awhile.

had another idea-tell me if this is just a coincidence.

when my eap was set at 3, my 95% pressure was 16.
Now with my eap at 0, my 95% pressure is 19.48.
my CA average went from 5.24 (eap on) to 2.63 (eap off).

I think I have to turn EAP back on?

Thanks for your ideas, Robin
2010 sleep study 63 AHI, 2014 3.0
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#20
(05-25-2014, 02:00 PM)readyforsleep Wrote: Too early to give any data on my 95% pressure number. As my
low pressure number increases I am experiencing gas issues so
I have had to backtrack a bit from 14 to 13.4. Think I'll
stay at 13 for awhile.

Hi readyforsleep,

Likely was just coincidence. The Max pressure the machine actually raised itself to (in order to prevent obstructive events) is much higher than 14 and is probably when most of the aerophagia was occurring.


(05-25-2014, 02:00 PM)readyforsleep Wrote: had another idea-tell me if this is just a coincidence.

when my eap was set at 3, my 95% pressure was 16.
Now with my eap at 0, my 95% pressure is 19.48.
my CA average went from 5.24 (eap on) to 2.63 (eap off).

I think I have to turn EAP back on?

Are you referring to EPR, exhalation pressure relief?

Turning off EPR is known to reduce the Central Apnea Index (CAI, the average number of CA per hr) for some patients (a significant minority), so turning off EPR could have been the cause for the reduced number of CA events.

As to whether turning off EPR could increase the pressure needed to treat your obstructive events and could therefore be the cause for your machine adjusting itself to a higher 95% pressure than on previous nights, I think this is unlikely.

On your standard APAP machine, I have not heard of any reason that lowering EPR (which would be raising EPAP, the pressure during exhalation, so that EPAP will be same as IPAP, the pressure during inhalation) could increase your pressure needs.

However, if instead of your AutoSet, if you were using a bi-level machine like the ResMed VPAP Auto, lowering Pressure Support (PS) may increase the number of obstructive hypopneas and Respiratory Effort Related Arousals. RERA events are arousals which were caused by respiratory effort but the reduction in airflow was too small to be scored as hypopnea. RERA events are not counted in the AHI.

I think it is more likely that normal variation in your pressure needs from one night to the next is the explanation for why your 95% pressure increased from 16 to over 19.

This is why it is often best to make adjustments after leaving the settings alone for a week or longer, so we have a better measure of the effect of a change.

Or perhaps you were in Rapid Eye Movement (REM, the phase of sleep when dreaming) while also on your back, which would be a double whammy for Obstructive Sleep Apnea, resulting in the need for higher pressure than on previous nights.

Of course if we take an over-the-counter sleep aid to help us sleep, the drug may increase our pressure needs, but also diet can have an influence.

Take care,
--- Vaughn

.
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.
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