Using low pressure to test for sleep apnea

General Discussion on any topic relating to CPAP and/or Sleep Apnea.
Doopz
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Using low pressure to test for sleep apnea

Post by Doopz » Sat Nov 20, 2021 6:15 pm

Hello, I have lost weight recently and was wondering if that cured my sleep apnea. I heard using a low pressure of 4 and checking if it goes above that or getting more events would be a way to test it without going to get a sleep lab test.
I know that a low pressure of 4 can still be enough to cure sleep apnea, but I thought I would give it a shot.

Here are the results:
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ChicagoGranny
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Re: Using low pressure to test for sleep apnea

Post by ChicagoGranny » Sat Nov 20, 2021 6:33 pm

Welcome to the forum!
Doopz wrote:
Sat Nov 20, 2021 6:15 pm
Here are the results:
Worthless for the intended purpose.

You left the machine on APAP. The machine is running the pressure up to 8 and 10 for significant periods of time. This is a clear indication that you still have significant sleep apnea that needs to be treated with CPAP. The machine would not have raised the pressure had you been breathing without assistance.

So, yeah, your test revealed something important - you still need CPAP.

Be glad you left the machine on APAP. Otherwise, you would probably have had a rough night.

Congratulations on the weight loss.

Doopz
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Re: Using low pressure to test for sleep apnea

Post by Doopz » Sat Nov 20, 2021 7:20 pm

Oh wow, thank you for the response. My min pressure is usually set to 8, is that fine in this instance?

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Julie
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Re: Using low pressure to test for sleep apnea

Post by Julie » Sat Nov 20, 2021 7:58 pm

Seems to be, though one night is not enough to be sure of anything.

BTW, apnea is so rarely ever 'cured', and if it ever is. it's usually because of an unusual circumstance (not just losing 'some' weight), but in general it's considered to be a condition, like diabetes, that you need to treat every day regardless of how well you test on some days or otherwise. Don't look to be cured as much as just how well you do most of the time, use Oscar and follow up on anything unwanted that does repeat more than once or twice.

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ChicagoGranny
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Re: Using low pressure to test for sleep apnea

Post by ChicagoGranny » Sat Nov 20, 2021 9:23 pm

Doopz wrote:
Sat Nov 20, 2021 7:20 pm
Oh wow, thank you for the response. My min pressure is usually set to 8, is that fine in this instance?
If you feel comfortable with 8.0, stick with it.

Technically, it could be lower and still keep your airway open. But some of us feel air starved at anything below 7.0 or 6.0.

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Miss Emerita
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Re: Using low pressure to test for sleep apnea

Post by Miss Emerita » Sun Nov 21, 2021 1:26 pm

Your pressure seems to change in response primarily to flow limitations. But you are right that an EPAP as low as 4 could be successfully treating apnea. I'm a case in point. I was diagnosed with moderate apnea -- lots of obstructive events and some hypopneas -- and my EPAP is 5. I almost never have OAs or Hs.

If you think you may no longer need PAP treatment, you'll want to have another sleep study.
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chunkyfrog
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Re: Using low pressure to test for sleep apnea

Post by chunkyfrog » Sun Nov 21, 2021 8:35 pm

It is possible that weight loss could have changed your pressure requirement.
Some find it goes down--others see it go up.
In either case, losing excess weight is a very good thing.
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dataq1
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Re: Using low pressure to test for sleep apnea

Post by dataq1 » Sun Nov 21, 2021 9:54 pm

I would respectfully disagree, attempting as you have, to get an impression if you should seek a new sleep study in consideration of your weight loss is justified.
Having said that, a couple of questions/suggestions are in order:

1) Is noon time your normal sleep start schedule?
2) Is your machine settings matched to the mask you are using? Resmed machines that are properly paired should show almost zero leak if you have a good seal. A poor seal, that is reflected in leakage really impairs the usefulness and accuracy of measurements.
3) Set your machine to ramp for the maximum ramp time permitted at the lowest pressure possible.(what your trying to do is use mimimal pressure support during your test.)
4) After your experiment click on the "events" tab on the left of the Daily Screen, then click on the ">" to get a listing of the events and when they occurred. Having identified the time when events occurred, expand the Flowrate graph so you can see the flowrate changes that signaled the event. (keeping in mind that if that event is occurring during a period of significant or rapidly changing leakage the assessment of the "event" is inconclusive.

Keep in mind that the differential pressure (difference between current barometric pressure and the maximum pressure generated by your pap equipment) is less than .3 psi. The pressure required to inflate a toy latex balloon is about 1-2 psi, so your pap equipment would not even inflate a toy balloon. OTOH , IF a differential pressure less than .3 psi is capable of remediating obstructions or stimulate "deeper" breathing, then the PAP therapy is accomplishing the desired result..... and that's what your seeking!

If you do decide to seek a new sleep study, of course you should talk with your medical profession for a prescription. If he feels that a new study is warranted, that's what you should. If possible you should try to get a full PSG, one in which your brain activity (EEG) and cardiac activity (EKG) and chest expansion straps is used (not a test where these parameters are implied from other measurements)

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Pugsy
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Re: Using low pressure to test for sleep apnea

Post by Pugsy » Sun Nov 21, 2021 10:10 pm

Advice to use the ramp feature isn't going to help.

OP is using a ResMed machine....when ramp is engaged nothing gets recorded other than pressure.
It won't report any events if they happen. It is just the way ResMed and ramp works.
We wouldn't know if anything happened or not.

Ramp pressure starts at 4 cm...and that is what the minimum setting started at anyway.

A better experiment if just looking for events themselves would maybe be fixed cpap mode and pressure set to 4 cm....forget ramp totally since nothing gets flagged when ramp is engaged.

Ultimately though the ONLY way to know for sure if the loss of weight makes someone get to also lose the cpap is another sleep study.
While I know 4 cm isn't considered to be much pressure at all....it's still enough to hold the airway open for a lot of people and prevent a truckload of apnea events from happening.
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dataq1
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Re: Using low pressure to test for sleep apnea

Post by dataq1 » Sun Nov 21, 2021 11:54 pm

Pugsy wrote:
Sun Nov 21, 2021 10:10 pm
Advice to use the ramp feature isn't going to help.
Yes, I should have more fully explained myself. What I intended to say was that after a period of low pressure (hopefully settled into nice sleep), then examine the pressure and events. Even if Flow limitations are noted, but the criteria for jacking up the pressure has not been achieved (after ramp), the pressure curve should be gradually increasing in a nice straight line. If on the other hand flow limitations (or other actionable events) occur then the curve would not be in a straight line (that is the "programmed increase") but jagged stair-step line caused by increases that are being commended in response to events.

I failed to go into that detail, and expected that the OP would return with another "experimental" OSCAR screenshot with an expansion of the area where the pressure was increasing.

I agree setting to CPAP at the lowest level is an alternative, I did not want to take the responsibility of telling the OP to completely avoid therapy during his experimental run.

We agree that the "for sure way" is to get another (hopefully full blown PSG), however I have the sense that the OP wanted to be able to have something to show his Dr. besides just a feeling that maybe he needs another sleep study. (afterall, if insurance is going to cover some part of the PSG cost, the Dr. will have to write a script of "medical necessity")

Hopefully our convo will be helpful to the OP. Thanks for spotlighting this

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Pugsy
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Re: Using low pressure to test for sleep apnea

Post by Pugsy » Mon Nov 22, 2021 12:23 am

Given the pressure fluctuations when trying the 4 cm minimum and the increases shown....something is going on that the machine wants to respond to. Now it might just be the flow limitations and it might not. It wouldn't be impossible for the increase to 6 or 7 or whatever to prevent full grown OAs or hyponeas.
Hence the thought that if someone wants to see if any OAs or hyponeas happen that 4 cm fixed is really the only option though not an ideal option. It's the best we can do with what we have at hand.

It wouldn't be impossible for the weight loss to have reduced the pressure needs as well.
This happened to me...I lost 25 pounds and I found that I went from needing 7 or 8 minimum to getting by with 4 or 5 minimum for the bulk of the night. The only time I saw really significant pressure increases was during REM which has always been the case for me since I have documented REM worse OSA....a lot worse in REM.
So while I was able to reduce the minimum significantly and it worked well in non REM.....in probable REM I still see/saw my usual rather high pressures well into the mid teens.

So while the reduction in weight did reduce some of my overall pressure needs it didn't totally eliminate the need for higher pressures.

I have a suspicion that is what happened in this situation. Something is still causing the machine to want to increase the pressure because if nothing happened then the pressure shouldn't have varied off of 4 cm all night long....so either REM or supine sleeping created something the machine didn't like.
Was it just the FLs? Dunno, might have been but also might have been something else.

If that report was my report I would assume that there's still enough of something going on in the airway that I need the machine.
If I just had to have proof I would try fixed 4 cm and see what happened... might give a clear cut answer and might not.
If a truckload of OAs and hyponeas happen...that's a fairly clear answer.
If not much happened except for the FLs....than that's when I would get another sleep study because I would love to not use cpap if I didn't just have to use it. Home study would work but only if a type 2 home study.

I guess what to do depends on how badly we want a for sure answer about something.
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Doopz
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Re: Using low pressure to test for sleep apnea

Post by Doopz » Mon Nov 22, 2021 12:54 am

dataq1 wrote:
Sun Nov 21, 2021 9:54 pm
I would respectfully disagree, attempting as you have, to get an impression if you should seek a new sleep study in consideration of your weight loss is justified.
1. No, I go to sleep around 8-9 am due to work schedule and wake up around 4ish. The data should have been longer but I need to adjust my machine's time which I just recently learned, since it resets at noon.
2. I use a Fisher & Paykel Brevida mask and have it set to pillows on the machine so it should be fine.
4. I'm pretty new to using Oscar so I'm not 100% sure if you wanted me to click on the individual times for a more detailed view. (These are from the same night as the original)
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I notice that some nights I wake up to readjust my mask, I sleep on my stomach so it must be pushing into the bed and coming off slightly. I'm not 100% sure how to fix this but maybe that is messing up some of the data.

I will try and use the fixed option tonight with a pressure of 4 and get back to you guys tomorrow if I can. Thanks for the responses so far.

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ChicagoGranny
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Re: Using low pressure to test for sleep apnea

Post by ChicagoGranny » Mon Nov 22, 2021 7:49 am

Doopz wrote:
Mon Nov 22, 2021 12:54 am
I will try and use the fixed option tonight with a pressure of 4 and get back to you guys tomorrow if I can. Thanks for the responses so far.
It's unclear which night you mean, but if you haven't done this yet, I recommend you do it on a night when you don't have much on your schedule for the next day. And if you wake up during the night under stress, you can change your pressure settings to a level that controls your apnea.
Doopz wrote:
Mon Nov 22, 2021 12:54 am
I notice that some nights I wake up to readjust my mask, I sleep on my stomach so it must be pushing into the bed and coming off slightly. I'm not 100% sure how to fix this but maybe that is messing up some of the data.
At least for the night dated 11/20, the leak is under good control.
Doopz wrote:
Mon Nov 22, 2021 12:54 am
I notice that some nights I wake up to readjust my mask, I sleep on my stomach so it must be pushing into the bed and coming off slightly. I'm not 100% sure how to fix this but maybe that is messing up some of the data.
In this blog post, Dr. Falcon explains the ideal position for stomach-sleeping with a CPAP mask - http://www.uarsrelief.com/sleeppositions.html

Doopz
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Re: Using low pressure to test for sleep apnea

Post by Doopz » Mon Nov 22, 2021 5:04 pm

Here are the results, my ahi looks fine but I felt like I was awake the whole night.
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Julie
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Re: Using low pressure to test for sleep apnea

Post by Julie » Mon Nov 22, 2021 5:36 pm

Any chance you're taking some medication that keeps you from deep sleep? Lots of OTC ones will do that.