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[Pressure] tweaking pressures for Bilevel
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justMongo Offline

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Post: #1
tweaking pressures for Bilevel
I'm on a bilevel machine at 14 IPAP / 9 EPAP. My AHI is a little higher than I'd like >5.

I'm unable to get a detailed report; only summary results from the LCD readout. My AI isn't bad. But, I am unable to tell a CA from and OA.

Does it make sense to increase just the IPAP when seeking a better result; or should both IPAP and EPAP pressures be raised the same amount keeping the same PR?

PR = IPAP - EPAP correct?

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.
01-29-2014 10:15 AM
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zonk Offline

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Post: #2
RE: tweaking pressures for Bilevel
(01-29-2014 10:15 AM)justMongo Wrote:  I'm on a bilevel machine at 14 IPAP / 9 EPAP. My AHI is a little higher than I'd like >5.

I'm unable to get a detailed report; only summary results from the LCD readout. My AI isn't bad. But, I am unable to tell a CA from and OA.

Does it make sense to increase just the IPAP when seeking a better result; or should both IPAP and EPAP pressures be raised the same amount keeping the same PR?

PR = IPAP - EPAP correct?
Yes if PR is pressure support
I would increase EPAP by 1 cmh2o but not IPAP so pressure support is also reduced by 1 cmh2o

To maintain the same level of pressure support, increase both EPAP and IPAP by 1 cmh20
But take it with a pinch of salt, I don,t use bi-level machine
01-29-2014 04:43 PM
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robysue Offline
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Post: #3
RE: tweaking pressures for Bilevel
(01-29-2014 10:15 AM)justMongo Wrote:  I'm on a bilevel machine at 14 IPAP / 9 EPAP. My AHI is a little higher than I'd like >5.

I'm unable to get a detailed report; only summary results from the LCD readout. My AI isn't bad. But, I am unable to tell a CA from and OA.

Does it make sense to increase just the IPAP when seeking a better result; or should both IPAP and EPAP pressures be raised the same amount keeping the same PR?
What's the breakdown of events in terms of Apneas vs. Hypopneas?

If most of the events are Hs, then it makes sense to raise the IPAP and leave the EPAP alone, which effectively increases the PS (pressure support) setting.

If most of the events are Apneas and you're reasonably sure that you are not prone to central apneas, then you probably need to increase both the EPAP and IPAP by the same amount.

On an in-lab bi-level titration, both IPAP and EPAP are increased in response to clusters of OAs, but only the IPAP is increased for clusters of Hs.
01-30-2014 12:33 PM
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Lindy Offline

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Post: #4
RE: tweaking pressures for Bilevel
I am on ipap if 23 and epap of 18. I feel like I don't exhale enough unless I try to really relax.
01-30-2014 03:35 PM
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justMongo Offline

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Post: #5
RE: tweaking pressures for Bilevel
(01-30-2014 03:35 PM)Lindy Wrote:  I am on ipap if 23 and epap of 18. I feel like I don't exhale enough unless I try to really relax.

WOW, those are high pressures.

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.
01-30-2014 04:30 PM
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Sleepster Offline
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Post: #6
RE: tweaking pressures for Bilevel
(01-29-2014 10:15 AM)justMongo Wrote:  I'm on a bilevel machine at 14 IPAP / 9 EPAP. My AHI is a little higher than I'd like >5.

If the lion's share of your AHI is due to CA's, then you could lower the pressure or just wait and see if it goes down by itself as you adapt. Assuming you're new to BiPAP therapy.

If the lion's share of your AHI is due to OA's or H's you can do as RobySue recommended.

Since you can't tell OA's from CA's it's hard to advise. Maybe just wait and see what happens. If the AHI doesn't go down by itself follow RobySue's advice and raise the pressure a bit. In my experience I've found that raising the IPAP lowers both my OA and my H indices.

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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.
01-30-2014 04:42 PM
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justMongo Offline

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Post: #7
RE: tweaking pressures for Bilevel
(01-30-2014 12:33 PM)robysue Wrote:  
(01-29-2014 10:15 AM)justMongo Wrote:  I'm on a bilevel machine at 14 IPAP / 9 EPAP. My AHI is a little higher than I'd like >5.

I'm unable to get a detailed report; only summary results from the LCD readout. My AI isn't bad. But, I am unable to tell a CA from and OA.

Does it make sense to increase just the IPAP when seeking a better result; or should both IPAP and EPAP pressures be raised the same amount keeping the same PR?
What's the breakdown of events in terms of Apneas vs. Hypopneas?

If most of the events are Hs, then it makes sense to raise the IPAP and leave the EPAP alone, which effectively increases the PS (pressure support) setting.

If most of the events are Apneas and you're reasonably sure that you are not prone to central apneas, then you probably need to increase both the EPAP and IPAP by the same amount.

On an in-lab bi-level titration, both IPAP and EPAP are increased in response to clusters of OAs, but only the IPAP is increased for clusters of Hs.

I am only able to read out my AHI and AI. (I have the custom data card and reader for the S8 -- but, cannot get things to play nice.)
My AHI exceeds 5. My AI is about 2.

My recording oximeter appears to validate those results.

So, I conclude that my Hypos are pushing my AHI above 5.

Looking at my 4 year old titration data, I showed occasional CA's at higher pressures. As I look at that data, I don't understand why they settled on 14/9. Other, than I think they were running out of time.

[Image: Titration_08AUG2009.jpg]

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.
(This post was last modified: 01-30-2014 04:58 PM by justMongo.)
01-30-2014 04:51 PM
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PaytonA Offline
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Post: #8
RE: tweaking pressures for Bilevel
Mongo,

Looking over that titration data, I think that I would have selected 17/12 or 18/9 but I am certainly not a sleep medicine specialist. It just makes sense to my brain that one should not pick pressures that gave zero events if subsequent higher pressures resulted in some events especially since after the first 5 time periods the time periods got much shorter. Does not make sense to me but like I said I do not have the background or training to make that call.

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01-30-2014 05:21 PM
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robysue Offline
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Post: #9
RE: tweaking pressures for Bilevel
(01-30-2014 04:51 PM)justMongo Wrote:  I am only able to read out my AHI and AI. (I have the custom data card and reader for the S8 -- but, cannot get things to play nice.)
My AHI exceeds 5. My AI is about 2.
The HI = AHI = AI, so if your AHI > 5 and your AI is around 2, then the HI is at 3 or higher.

Quote:So, I conclude that my Hypos are pushing my AHI above 5.
That's a reasonable conclusion. You might want to up just the IPAP by a cm or two and leave it there for a week or so to see what happens to the AHI and the AI (and hence the HI).

Quote:Looking at my 4 year old titration data, I showed occasional CA's at higher pressures. As I look at that data, I don't understand why they settled on 14/9. Other, than I think they were running out of time.

[Image: Titration_08AUG2009.jpg]
If you look at the data carefully, you will notice that 14/9 appears to be high enough to control the OAs and the Hs (the #OAs = 0 and #Hs = 0), although it looks as though you got mighty little sleep at that pressure setting. Above IPAP = 14 and EPAP = 9, you'll notice that the number of centrals grows with the pressures. That's probably why they didn't go with a higher pressure setting.

In my non-sleep professional, non-doctor view, I think the question to ask is why didn't they just go with a pressure setting of 13/6. Your sleep efficiency was good and there were no obstructive events in the 21 minutes at that pressure. Or perhaps 13/7 when you had 40 minutes of REM sleep with no obstructive events. (But there were 3 CAs in the 57 minutes at 13/7.)

Out of curiosity: Have you ever tried sleeping at 13/7 or 13/6 to see if the AHI goes down instead of up??


And by the way, those ridiculously high AHIs based on 1-3 CAs at pressures of 15/8, 15/10, 15/11, and 17/10 are based on ridiculously small amounts of sleep. For example, let's look at the AHI computation for 15/8. There's one CA scored at 15/8, but the reported AHI = 150. Here's how that number was computed:

According to the data, they had you at 15/8 for a whopping 3.8 minutes. And your sleep efficiency at 15/8 is reported as 10.5%. In other words, you were only asleep for 10.5% of the 3.8 minutes that the pressure was at 15/8. And 10.5% of 3.8 minutes is a grand total of 0.339 minutes, which equals 23.94 seconds. Let's round that to 24 seconds and note that 24 seconds = 0.4 minutes, and 0.4 minutes is 10.52% of 3.8 minutes. So it's likely that at a pressure setting of 15/8, you slept for a whopping 24 seconds. And in those 24 seconds you had one central apnea. Since AHI for 15/8 is equal to (# of events)/(Sleep time at 15/8 measured in [i]hours[/], we first have to convert the 24 seconds of sleep time to hours:

24 seconds = 24/60 minutes = 0.4 minutes = 0.4/60 hours = 0.00667 hours of sleep at 15/8 cm.

So the AHI at 15/8 is scored as:

(1 CA)/(0.00667 hours of sleep at 15/8) = 150.0 when rounded to one decimal place.

And finally, was this a split study? There are only 3 hours of time recorded in the pressure data. Did they have you sleep without the mask for the first part of the night and then wake you up to put the mask on your nose for the rest of the night?
01-31-2014 02:09 AM
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robysue Offline
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Post: #10
RE: tweaking pressures for Bilevel
(01-30-2014 05:21 PM)PaytonA Wrote:  Mongo,

Looking over that titration data, I think that I would have selected 17/12 or 18/9
There was NO sleep recorded at either of these pressures. In fact there was NO sleep recorded at any pressure level at or above 17/12. That's why all those pressures have an AHI = 0.0.

Quote:It just makes sense to my brain that one should not pick pressures that gave zero events if subsequent higher pressures resulted in some events.
You have to get somesleep time for the AHI numbers to be meaningful. And it looks as though there was mighty little sleep scored after the pressures were raised past 15/8.

The titration algorithm does not raise the pressure setting for CAs since additional pressure does nothing to prevent them and additional pressure can trigger more of them. When time is NOT short, the titration algorithm specifies a five minute waiting period after raising the pressure to see if the breathing stabilizes and it's also common place to not raise the pressure for an isolated event.

The curious things about this titration data in my eyes are these: Why was the tech changing the pressure so frequently in the absence of OAs and Hs? Why was the tech changing the pressure in the absence of SLEEP? My guess is that there was some persistent snoring present and the tech was titrating the pressure up in an effort to end the snoring. Or perhaps this is one of the rare labs that attempts to titrate all flow limitations away.

It would be real interesting to see the summary graphs for this sleep study and see when the pressure was raised so high and why it was apparently lowered back down from the IPAP = 18 settings. My guess is that the tech bumped up both the IPAP and EPAP in response to the OA that happened at 15/11 and that pressure increase woke the OP up. And the OP couldn't get back to sleep until the tech lowered the pressure back down after giving the OP about 20-30 minutes to get back to sleep.
01-31-2014 02:24 AM
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