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+--- Thread: Why does EPR help with flow limitations? (/Thread-Why-does-EPR-help-with-flow-limitations)
RE: Why does EPR help with flow limitations? - EddyDee - 10-29-2023
(08-25-2023, 10:13 AM)chemmkl Wrote: If you have a ResMed machine, I think this video explains it pretty well: https://www.youtube.com/watch?v=GaXA0ZIWj1Y
...
I never trusted Uncle Nicko, but this video nailed it for me. I'm no expert but even I can tell from this that he just doesn't have a clue. The graphs he presents are actually nice and revealing, but he misinterprets them in an almost laughable way.
It's really quite simple: ResMed's EPR reduces EPAP from the value of "Pressure".
If you are on "Pressure = 10" and "EPR = 0" then EPAP = IPAP = 10.
If you now set "EPR = 1", and leave "Pressure = 10", ResMed reduces EPAP to 9, and IPAP remains at 10.
Furthermore, ResMed leaves the actual mask pressure at the EPAP level for the entire respiratory cycle except during active inhalation (unlike other manufacturers). You can see this very clearly in OSCAR on the Mask Pressure graph.
So if you need a minimum EPAP of 10 to overcome obstructive events, then setting EPR to 1 while leaving "Pressure" unchanged will reduce your EPAP below that threshold. In order to maintain EPAP at 10, you need to raise "Pressure" by the same amount as the EPR setting. That's all there is to it.
But Uncle Nicko jumps up and down and says "look, when you enable EPR on a ResMed you have to raise your Pressure, but you don't have to do that on other machines! So ResMed EPR is evil".
And then he actually goes on to present a great example of when enabling EPR achieves the expected result of reducing FLs! Go figure...
Honestly, just stay away from this nonsense.
RE: Why does EPR help with flow limitations? - EddyDee - 10-29-2023
(05-21-2022, 03:07 PM)breathestopbreathe Wrote: Let’s say I have no flow limitations with settings IPAP = 8 and EPR = 3. I then turn EPR off. Why may I have inspiratory flow limitations now even though my IPAP is the same, providing the same amount of mechanical assistance to increase tidal volume, shorten inspiration duration, and prevent the airway from collapsing during inspiration (as only the EPAP has changed)?
I don't know where this comes from. Are you saying that this is what happens in actual fact?
This sounds like a claim that if you have no FLs when EPAP =5 and IPAP =8, then you will have FLs when EPAP = IPAP = 8.
I simply don't think this is the case.
RE: Why does EPR help with flow limitations? - Lucky7 - 10-29-2023
(08-25-2023, 10:13 AM)chemmkl Wrote: If you have a ResMed machine, I think this video explains it pretty well: https://www.youtube.com/watch?v=GaXA0ZIWj1Y
It's based on this scientific paper: Zhu, Kaixian, et al. "Pressure-relief features of fixed and autotitrating continuous positive airway pressure may impair their efficacy: evaluation with a respiratory bench model." Journal of Clinical Sleep Medicine 12.3 (2016): 385-392.
So essentially on ResMed machines when you enable EPR in AutoSet they increase the inspiratory pressure significantly more than when EPR is off in order to keep the apnea under control due to the algorithms they have for Auto CPAP (this does not happen with similar EPR systems from other manufacturers). So if your maximum pressure to keep your airway open is around 12cmH2O without EPR, with EPR is going to be around 14cmH2O. This explains why just enabling EPR helps with inspiratory flow limitations: is using higher pressure. At the same time, because now you respiratory support is higher (14 inspiratory, 11 expiratory if you have EPR set to 3cmH2O) the pressure differential increases the flow of air out of you lungs keeping your airway open for the regular obstructive apneas as well.
This is a great paper everyone should read it.
Noteworthy that ResMed makes no therapeutic claims for EPR. Because, if they COULD, they sure would. "Our therapy is superior" would translate to more revenue.
RE: Why does EPR help with flow limitations? - Frankiboy - 10-30-2023
If 12 cmH2O is set, but the result with EPR is about 14 cmH2O, what pressure is applied during the mask test?
You could measure this with a suitable measuring tool and know that it is correct.
RE: Why does EPR help with flow limitations? - Sleepy Quixote - 10-30-2023
Interesting paper, based on a bench test rather than human being. For me personally I can show conclusively through this last six months data the EPR improved efficacy of my treatment, both in improved sleep quality due to fewer auto adjustments and lower pressure increases to control flow limitations. I'm a very light sleeper and any pressure change disturbs my sleep, minor leaks wake me up, pressures above 9.6 consistently wake me up and I have to reset the machine to be able to go back to sleep, with EPR helping to minimize flow limitations I get fewer pressure changes and smaller increases when flow limitations do occur. I have run the machine in CPAP mode titrating up from 7.4 up to 7.8 (about as high as I can tolerate and still fall asleep and sleep comfortably. Had the highest flow limitations in the last six months during during that study. Meaning I would have had to continue titrating upward to control flow limitations to a point where sleep quality would significantly degrade due to discomfort caused by the pressure and the inevitable leaks that come with it. I have titrated up from (min 5.6 max 9.6) up to (min 7 max 9.6) in APAP mode EPR off over a two month period, had the the second highest average flow limitations during that study. Looking at the overview chart it is very clear the day I turned on EPR, the average flow limitations reduced clearly from that point forward regardless of the titration schedule I was experimenting with. Some better some worse but none with higher averages than straight APAP or EPR off. I currently run Min 7.8 max 9.6 EPR 3, consistently have 99.5% flow limits below 0.07 and a steady stream of 0.00 in the 95% flow limits category (barring the occasional stuffy head or run of positional issues). My pressure graph no longer looks like a sawtooth, some nights its darn near a straight line, blip here and there, the flow rate graph is smoother too, EPR works for some people, I am one of those. Now that the PLMD is under control I actually feel like a normie when I wake up in the morning.
I would wager that if people actually took EPR seriously and did very careful step by step titration studies changing one parameter at a time over time, keeping in mind the plethora of other confounding factors to getting lower flow limits, especially the many varied positional issues and various causes of nasal congestion, more people would find a higher level of efficacy in their treatment.
Attached a screen shot of my last six months of experimenting with the Airsense 11 'features' be sure to scroll the image to the right to see the end.
Keep at it! That's how we het good at it!
RE: Why does EPR help with flow limitations? - EddyDee - 10-30-2023
(10-30-2023, 02:00 AM)Frankiboy Wrote: If 12 cmH2O is set, but the result with EPR is about 14 cmH2O, what pressure is applied during the mask test?
You could measure this with a suitable measuring tool and know that it is correct.
You can see this very clearly in OSCAR in the mask pressure chart.
RE: Why does EPR help with flow limitations? - EddyDee - 10-30-2023
(10-29-2023, 10:32 PM)Lucky7 Wrote: This is a great paper everyone should read it.
Noteworthy that ResMed makes no therapeutic claims for EPR. Because, if they COULD, they sure would. "Our therapy is superior" would translate to more revenue.
I think it's for a different reason: the Aircurve is tested clinically as a Bi-level machine, while the Autoset and other basic models are not. They have no reason to test the cheaper machines as Bi-levels.
RE: Why does EPR help with flow limitations? - Lucky7 - 10-30-2023
(10-30-2023, 08:38 AM)EddyDee Wrote: I think it's for a different reason: the Aircurve is tested clinically as a Bi-level machine, while the Autoset and other basic models are not. They have no reason to test the cheaper machines as Bi-levels.
I sort of see your point. Sort of.
Imagine the ad copy thou "our APAP machines are clinically superior to X manufacturers".
On the other hand, at this point they essentially dominate the market. So yeah, fair point.
RE: Why does EPR help with flow limitations? - Lucky7 - 10-30-2023
(10-30-2023, 04:59 AM)Sleepy Quixote Wrote: Interesting paper, based on a bench test rather than human being. For me personally I can show conclusively through this last six months data the EPR improved efficacy of my treatment, both in improved sleep quality due to fewer auto adjustments and lower pressure increases to control flow limitations. I'm a very light sleeper and any pressure change disturbs my sleep, minor leaks wake me up, pressures above 9.6 consistently wake me up and I have to reset the machine to be able to go back to sleep, with EPR helping to minimize flow limitations I get fewer pressure changes and smaller increases when flow limitations do occur. I have run the machine in CPAP mode titrating up from 7.4 up to 7.8 (about as high as I can tolerate and still fall asleep and sleep comfortably. Had the highest flow limitations in the last six months during during that study. Meaning I would have had to continue titrating upward to control flow limitations to a point where sleep quality would significantly degrade due to discomfort caused by the pressure and the inevitable leaks that come with it. I have titrated up from (min 5.6 max 9.6) up to (min 7 max 9.6) in APAP mode EPR off over a two month period, had the the second highest average flow limitations during that study. Looking at the overview chart it is very clear the day I turned on EPR, the average flow limitations reduced clearly from that point forward regardless of the titration schedule I was experimenting with. Some better some worse but none with higher averages than straight APAP or EPR off. I currently run Min 7.8 max 9.6 EPR 3, consistently have 99.5% flow limits below 0.07 and a steady stream of 0.00 in the 95% flow limits category (barring the occasional stuffy head or run of positional issues). My pressure graph no longer looks like a sawtooth, some nights its darn near a straight line, blip here and there, the flow rate graph is smoother too, EPR works for some people, I am one of those. Now that the PLMD is under control I actually feel like a normie when I wake up in the morning.
I would wager that if people actually took EPR seriously and did very careful step by step titration studies changing one parameter at a time over time, keeping in mind the plethora of other confounding factors to getting lower flow limits, especially the many varied positional issues and various causes of nasal congestion, more people would find a higher level of efficacy in their treatment.
Attached a screen shot of my last six months of experimenting with the Airsense 11 'features' be sure to scroll the image to the right to see the end.
Keep at it! That's how we het good at it!
VERY cool. Could you describe your titration protocol if you wouldn't mind?
RE: Why does EPR help with flow limitations? - Sleepy Quixote - 10-30-2023
@Lucky7
I use the word titration in the loosest sense. I have no way to change settings while sleeping so I look at each night as a phase of the titration.
First decide what to test, reduce variables to the minimum. Change no more than one setting in each study for the duration. I usually run a test over a week or two depending on what causes termination, if improvements continue, the study continues until they don't, then step back a couple settings to best result from test and confirm repeated result. Take extensive notes in the OSCAR notes side bar regarding analysis of each event.
Like most everyone else who gets sent home the thing was set up generically, my particular set of 'optimal' (snark) settings was - APAP Min 5.00 cmH2O Max 15.00 cmH2O,
Climate Control Auto, EPR 3 Full Time, Ramp on, Humidifier On, level 3, basic patient view, standard response, climate line enabled smart start on.
Lost my first weeks data because the DME didn't bother with setting the time zone, figured that out when I installed OSCAR and the time was very wrong. Spent a couple of weeks before getting the machine watching every YouTube video the two main pappers (will not mention names) had in their libraries... so immediately entered the clinicians menu and cranked up the humidity because good, shut off the ramp, because bad. Turned off EPR because bad... according to the CPAP interwebs wizards. Spent about a month trying everything and anything suggested in batches. Was miserable, no improvement in sleep quality, actually it was worse because of the ill managed machine.
Finally came back here and started reading the pearls of wisdom from many contributors, low and behold with a few tweaks things started getting better, slightly. Took the advice of someone here who said only change one thing at a time and analyze the results. Went with that for a while and things improved a little more, still not the miracle the sleep folks promised. Still tired, exhausted. Decided to get serious. Do an APAP titration to find my most effective and tolerable minimum pressure. Capped my max at 9.6 because I already knew from a plethora awakenings that 9.6 was the maximum I could tolerate and still sleep. Set humidity in the middle and left it there for the duration. Left ramp off, left EPR off, the only nightly change was minimum pressure in the small increments until I reached 7, just tolerable, besides it was a magic number around here. Titrated all the way back down to 5.6 compared charts and stats, 7 had the best results, though still not nearly what I call efficacious. Discovered EPR here from Sleeprider, adjusted EPR up to 3 over a week, numbers improved. Stepped up to 7.2 and found it quite comfortable and improved sleep just a bit more. Did a short study on static CPAP because, well, its really the only way to go according to one particular pap guru. No need to test it more than a week, sleep quality tanked, flow rate graph went south and flow limitations went north. End of study. Went back to min 7.2 max 9.6 - EPR3, began a new study to find the highest minimum pressure tolerable with EPR 3 engaged. Over a two week period gradually increased minimum until I hit 8.6 as highest sort of comfortable pressure, compared all the previous stats and arrived at the minimum of 7.6 as having the best overall numbers over time. Ran that number for several months, then started experimenting with things like Flonase, during that study, Flonase was the only change made, first one night, then two in a row then three in a row, changing nothing else, watching primarily flow limitations. Discovered it is quite helpful, though I only use it now if flow limitations start to climb, rather than upping pressure I use Flonase for a few nights, the effect usually lasts a week or so. Bumped up to 7.8 to extend the lower flow limit periods between using it. (Several other experiments, no need to go on and on) [already have]
For me personally, I also have severe, barely treated PLMD so I have to squeeze every bit of efficacious APAP treatment I can get to even feel human, the only way I have found to get there is listen to the good folks here, try one thing at a time over an extended period and treat it like an extended titration study. Take notes, analyze the graphs, and above all use flow limitations as the primary driver in making decisions about settings.
Keep at it! That's how we get good at it!