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Lower AHI and FLs with lower pressure
#1
Lower AHI and FLs with lower pressure
Not at all what I expected.
In my 5 months on CPAP I've studied a lot and tried a lot of things, but my results have always been inconsistent. Treated AHIs between 2-10 and varying a lot, seemly with the moon or aliens.

Recently, in order to have tried everything, I went with lower than 'normal' pressure settings.
For 5 nights straight I've had consistently lower AHI and FLs with EPR set to 3 and min = 6.2(ish), max = 7(ish). I'm trying ma at 6.6 max tonight to see what happens.
I'm aware that I'm getting varying PS between 2 and 3cmH2O, but that seems to work great for my FLs. FL max is 0.08 now vs 0.15 with 9 EPR3.

Has anyone experienced this? Is it normal?
I never had a clinic titration, my doc sent me home with a Dreamstation set 4-20, AFlex1. It used to climb up to 16cmH2O+, and my charts were full of OAs and CAs.
My home sleep study showed Hypopneas only (29.1AHI with desats down to 86%), no OAs or CAs.
The Resmed I bought seems a lot smarter and never climbed above 13 when set 8-20cmH20. Results varied between 2 and 7. Since using the Resmed I've not had an apnea and very few hypopneas.
However, now that I've limited it's max, it's performing way better and more consistently, results have been less than 2AHI for 4 nights straight and I've been feeling great. My smart watch is showing deep sleep of nearly an hour, and REM of 2:30ish!

Any explanations? Perhaps a clinic titration would have shown an ideal pressure of 6? Maybe I don't have OSA at all (no apneas with current EPAP of 4cmH20, I can't go lower), could it be UARS that just requires a little PS at low pressure levels?
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#2
RE: Lower AHI and FLs with lower pressure
Hypopneas generally don't require as much pressure to treat as OAs. The higher EPAP could have been making flow limitations worse.
Nothing I post is medical advice and should not be taken as such, always consult a medical professional for guidance.
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#3
RE: Lower AHI and FLs with lower pressure
Whatever works to get you the therapy and rest needed. It could be your unique therapy needs were disrupted with higher pressures. I see no issues with doing what works. See how it trends for a few days to see if it's continuing well.
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEBSITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#4
RE: Lower AHI and FLs with lower pressure
(02-22-2020, 12:15 AM)SarcasticDave94 Wrote: Whatever works to get you the therapy and rest needed. It could be your unique therapy needs were disrupted with higher pressures. I see no issues with doing what works. See how it trends for a few days to see if it's continuing well.

Thanks, maybe I'm just gentle little flower after all!!  Too-funny

Last night was the best yet since trying these lower limited settings!
Min = 6cmH2O
Max = 6.6cmH2O
EPR=3 (so actually 2 - 2.6cmH2O)
This makes 6 nights straight less than 2AHI with this range of settings. I've only got about 8 nights in the previous 5 months less than 2 AHI.
Going through this flow rate chart, two of CAs are only 10 sec and follow sighs with normal breathing recovery, so I'll ignore them. I think the real AHI is actually 0.55.

The one thing I have noticed - minute vent/tidal volume is slightly lower last night (6.38/480). I'm 192cm and 90kg, is this the range you'd expect?

My better nights at higher pressures were 6.88/540 MV/TV. Sleeping RR has always been 12-13ish. The last 6 nights with 7cmH2O or less has been 6.25/500avg. Is that still ok for my height/weight?


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#5
RE: Lower AHI and FLs with lower pressure
Just info for learning: as I have it, the AirSense 10 Auto can go down to 4 cm H2O, some other machines can get down to 3; a low-ish setting of 6 with EPR 3 still only nets a 4.

Regardless of number, if the therapy is working then that's what counts.

Best wishes it continues, and as you're upside down, be careful not to spill your Coffee
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEBSITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#6
RE: Lower AHI and FLs with lower pressure
When you first started therapy, your thread requesting setting changes showed  you were mostly disturbed by CA events and pressure fluctuations. http://www.apneaboard.com/forums/Thread-...ce-request  You reduced EPR at that time, and I don't recall seeing any more updates on your therapy. Reducing CA was effective in reducing CA events, but the reduced pressure had the same result. You are now using a minimum pressure of 6.0 and maximum pressure of 6.6 with EPR 3. Your EPAP never moves form 4.0 cm and your IPAP pressure fluctuates only 0.6 cm.  This has effectively reduced your maximum EPR to 2.5 and with lower, more steady pressure, reduces the CA events.

So if we compare old to new. we can conclude that your treatment emergent CSA responded in a positive way to both reduced EPR and reduced pressure.  This is an expected result, and it's good that you have achieved such good results using CPAP. I'll add that keeping therapy threads together helps us to tie together the cause/effect of setting changes.

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Sleeprider
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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.
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#7
RE: Lower AHI and FLs with lower pressure
Thanks guys, much appreciated
With the freely shared advise on this forum I feel like I'm really starting to understand the interplay of various settings in CPAP with the mechanics of ventilation.

@sleeprider - the thread you're referring to is my early Resmed chart. My Dreamstation charts for months prior to that were a total mess.
Can this thread be merged with the original you're referring too? I should have just gone back to that one.

I'm going to leave the settings where they are and report back in another week.

Lessons I've learned in the last 5 months that I'd tell my younger self in hindsight:
* The sleep study is the key. In my case - no CAs or OAs in sleep study. Therefore I should have known that CAs and OAs after CPAP were/are treatment emergent. That's right, OAs can be treatment emergent too if your doc sends you home with an auto machine set 4-20. Knowing that, coupled with the knowledge shared on this forum would have gotten me to a solution quicker
* Hypopneas (in the absence of OAs) require very little pressure to solve, and they seem to respond even better to a little pressure support. The AirSense is a superior machine to the Dreamstation in this instance. Resmed incorrectly call their PS feature "EPR". It's not expiratory pressure relief, it's inspiratory pressure support and should be named accordingly to avoid confusion
* More pressure is not always more in CPAP world, in fact in some cases less pressure is more. There seems to be consistent dogma on CPAP forums that one should use auto mode and leave maximum at 20cmH2O to "see where the machine goes". You often see people saying that the machine "won't go there unless it needs to", and that's simply not true. Any machine simply responds to what it detects based on it's response algorithm. It may be that this is good advise in the majority of cases, but certainly not all cases, and I don't think it shouldn't be so universally advised. If you experience treatment induced apneas (CAs and OAs) beyond a certain pressure and the machine crosses your "pressure threshold" in auto mode then you're in a world of misery. Maybe my case is in the minority, but minority lives matter too!  Smile
* A slack jaw is the enemy of CPAP treatment. If your mouth is prone to dropping open then cervical collar and mouth taping seem to be the best immediate resolutions. This includes for FFMs, which I also tried for a long time, FFM don't really protect against an open mouth in the sense that accurate event detection and response is still compromised, plus it significantly increases leaks. Tongue suck may work eventually for some people, but I'm buggered if I can master it  Wink
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#8
RE: Lower AHI and FLs with lower pressure
Excellent post! I can merge the threads, but no need to do so. Thanks
Sleeprider
Apnea Board Moderator
www.ApneaBoard.com

____________________________________________
Download OSCAR Software
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Optimizing Therapy
Organize your OSCAR Charts
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Mask Primer
How To Deal With Equipment Supplier


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.
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#9
RE: Lower AHI and FLs with lower pressure
You got it figured out. These machines adjust pressure whenever obstructive apneas, hypopneas, flow limitations or snore are present. They aren't smart enough to know if increasing the pressure actually helps though so the only way to know is to try different settings and see how it effecte you/your data. On some people the increasing pressure helps but on other people it hurts, it all depends on what is causing the obstruction/restriction and whether or not increasing pressure helps open up the airway. I am a strong believer in figuring out if increasing pressure provides any benefit and if it doesnt then using CPAP mode to avoid pressure fluctuations.

Your ventilation numbers presented are within normal ranges. Tidal volume is usually 6-8 ml/kg.

I would change to cpap mode or set min = max in apap mode. To get the best treatment of flow limitations and the best ventilation start with a pressure of 7 and EPR of 3. If having central apneas you can reduce pressure slowly until they improve, this will slowly lower effective EPR(rather than having to drop by a whole cm by dropping EPR to 2).

I dont worry about flow limitation max, that stat is affected by a single breath which can be happen at any time and often isn't indicative of a flow limitation problem (often times occuring when awake etc). 95% value is more useful but is probably 0 or near 0 in your case as flow limitations appear to be minimal.

Just a little bit more information. EPAP is what helps maintain an open airway. EPR/PS increase flow by providing a pressure differential. EPR being called expiratory pressure relief makes sense, if you look close at OSCAR data you will notice that peak pressure(IPAP) isn't reached until near the end of inspiration. The inspiratory support is minimal as pressure differential is small during most of inspiration then the full pressure differential is useful during expiration. I personally believe that if they offered a second waveform with earlier IPAP that it would help users that suffer primarily from inspiratory flow limitations. A lot of these users have to step up to bilevel machines and higher levels of PS to find appropriate treatment because of this.
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#10
RE: Lower AHI and FLs with lower pressure
This is based off the Resmed S9 Autoset.  If you set the S9 to CPAP mode and have the EPR option enabled, an option will appear to change the time to reach the IPAP pressure.   The option name is "EPR Inhale".  It provides the selection between "med" (default) and "fast".  I tried the fast setting and found very annoying.  It felt like getting a jolt of air on each inhale.  If you are using an FFM, it will really make the mask jump.  I'm uncertain if Resmed brought this option over to the AS10.
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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.
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