not understand EPR setting

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AffectionateSpringGreenCheetah8414 +0 points · 12 months ago

Hi, I am using RESMED airsense 10, regarding the EPR setting, 1 to 3, which one is the best? just want to understand the what is the difference of different pressure relief mean. thank you

http://www.resmed.com/assets/documents/technology/epr/fact_sheet/1011940_epr_fact-sheet_row_eng.pdf

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sleeptech +1 point · 12 months ago Sleep Commentator

I'm glad you asked. This is one of my favourite topics to bend people's ears about. EPR stands for Expiratory Pressure Relief. It is a function that ResMed introduced in their S8 and later models and it is the the same as C-Flex on Respironics machines, which they have had since the M series (although I'm sure both companies would swear blind they're totally different). The idea is to drop the pressure slightly on expiration in order to make the pressure more tolerable. Sounds reasonable but it is, in fact, a huge problem and should be avoided in almost every instance. "Why?", I hear you ask. I'll try not to get into too much detail explaining this.

The first problem is that EPR (and C-FLEX) lower your effective CPAP pressure. For example, if you need a CPAP 12 to breathe properly, but have EPR set on 3, you will only be getting an effective CPAP pressure of somewhere between 9 and 10, and because this is lower than is required you will obstruct. What will often happen next is that the patient will complain of persistent symptoms (because their OSA is not being adequately treated) and their download will show a higher than desirable AHI, so the pressure will be turned up making it less tolerable, increasing leak problems and leading to overall lower compliance with therapy. I have had to deal with this on more than one occasion.

The second problem is that by raising and lowering the pressure as you breathe, EPR actually increases the amount of air that you are breathing. With standard CPAP the pressure is constant, and the movement of air in and out of you lungs is done purely by your own respiratory muscles, so the amount of air you breathe is the normal amount that you should be breathing. All CPAP does is hold your airway open so that you can breathe normally. EPR works like low level BiPAP. As you breathe in the pressure increases and as you breathe out it decreases, which means that more air is moving in and out of your lungs than normal - the EPR is slightly augmenting your respiratory effort. This may sound all well and good, but there is a reason that you breathe the amount you do. Too little is a problem, we all know that, but too much can be a problem too. The extra breathing work done by EPR can be enough to hyperventilate you, sending your CO2 level too low which, in turn, causes central events. Again, I have recorded evidence of this happening.

Where I work, we only ever allow our patients to use EPR or C-Flex if they have had a sleep study with it and we can verify that it is not causing any harm. Otherwise we do not use it at all. I can think of fewer than 5 people who have actually had some benefit from using EPR/C-Flex in all my years of being a sleep tech. The people who sell the machines and the reps for the companies who make them will extol the virtues of EPR/C-Flex and tell you that it is perfectly safe. IT IS NOT. One of the engineers who designed the system admitted as much to another tech I work with.

So, to sum up, do not use EPR/C-Flex unless you have had a sleep study with it to make sure it's OK. It's not worth the risk. On ResMed machines EPR can be set to ramp only which is much less risky. Otherwise, if you think you really need it, get a study done while using it. As always, consult with your doctor, but you will probably find that they know nothing about this, as most of them don't in my experience.

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AffectionateSpringGreenCheetah8414 +0 points · 12 months ago

thanks you.

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AffectionateSpringGreenCheetah8414 +0 points · 12 months ago

is there a way patient can tell the difference between on or off

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sleeptech +0 points · 4 months ago Sleep Commentator

It says in the menu

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AffectionateSpringGreenCheetah8414 +0 points · 12 months ago

so could you use plain English easy to allow me understand: Setting 1 reduces pressure on exhalation by 1 cm H2O. meaning? pressure and exhalation relationship. thanks again.

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sleeptech +0 points · 12 months ago Sleep Commentator

Yes, an EPR of one should drop the pressure by approximately 1 cmH2O. EPR of 2 drops the pressure by 2 cmH2O and so on. Sorry that explanation was confusing.

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EasygoingAquamarineMagpie7538 +0 points · 12 months ago

Well, now you can think of 6, because it has been of great benefit to me. ;-) Made the treatment much more tolerable as I could not tolerate the constant pressure of 17 and would have probably quit (or just been miserable). Are the Central Apneas as detected by the ResMed not accurate? I rarely get one. I had one during my sleep study. My AHI is always 2 or lower.

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sleeptech +0 points · 12 months ago Sleep Commentator

Your ResMed machine should be able to detect the central apnoeas if they develop, so you're probably fine. I'm glad it's helpful for you. For most people EPR is probably harmless, it's just that there are risks, and the number of people for whom it is a problem, albeit the minority, is still pretty significant. Even a small proportion of sufferers from a condition as common as OSA can be tens of thousands of people (possibly even hundreds). This is exacerbated by the fact that the manufacturers tell everyone that it's completely harmless and everyone should use it, so most CPAP machines have it turned on by default. As usual, proper education is the key here, along with healthcare professionals who are prepared to put in all of the work required to do the job properly.

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Goofy3 +0 points · 4 months ago
  1. If pressure is set on 12 with an EPR of 3 doesn't the machine on inhalation go up to 12 and then on exhalation go down to 9? It is not an average.
  2. How can EPR increase the amount of air you breathe? With a setting of 12 air is going in at 12 and on exhale EPR reduces to 9 as lungs exhale but no more air is going in.
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sleeptech +0 points · 4 months ago Sleep Commentator
  1. Not quite sure what you mean here...

  2. That is how it increases the amount of air you breathe. Because the pressure increases every time you inhale, it is pushing more air in. It is functioning just like BiPAP. I'm struggling to think of a better way to explain it. Sorry.

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kenzo +0 points · 19 days ago

So it sounds like this would be useful for a person like myself that uses a BiPap. I've been searching for a smaller travel BiPap and I haven't found anything that looks like it would work. However the Resmed AirMiniā„¢ AutoSetā„¢ Travel CPAP Machine has EPR which leads me to believe I could use it as a BiPap replacement. My bipap settings are 14 inhale 11 exhale so it looks like this may be an option for me.

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Sierra +0 points · 19 days ago Sleep Commentator

Yes, I believe you are correct. It sounds like your BiPAP is set to an EPAP of 11 cm, with 3 cm of Pressure Support. That is essentially the same as a ResMed APAP set to 14 cm of pressure with 3 cm of EPR.

I would think through the pros and cons of a travel CPAP though. We have a Z-1 that goes unused. The new AirSense full APAP 10 has a nice travel bag that is fairly compact, and it has two velcro straps on it that will secure it to a roller travel suitcase that has a two pipe extension handle. And, a CPAP is a medical device, so it does not count as an additional item or weight to your standard travel allowance.

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Feynman +0 points · 2 months ago

Thanks tons for this knowledgeable post!

Suddenly the last week or two my CPAP therapy went to hell. AHI was 5x higher than normal. Getting terrible diaphragm muscle pains in the morning. Feeling tired. What the he!! happened? So I checked machine settings and saw EPR was on and set to 3. What the heck is EPR? So I Googled it and found this post.

Turned EPR off and slept like a baby last night. AHI is way way down Thank you.

Not sure how it got turned on, but glad its off now

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Cyberslayer +0 points · 28 days ago

Had my sleep doc turn it down first as it was very annoying. Still hated it it so I had him turn it off completely. No patient option to adjust or turn off on my machine. Very comfortable now. I could tell that when my cpap thought I was asleep it would turn it off automatically. Sometimes I would try to fool machine into thinking I was asleep so it would shut it off. My doc thought that was very interesting and laughed about it. Now to find the perfect mask. Smalls are too narrow on my mouth but mediums are too tall on my nose. And I wish headgear straps were much WIDER. I wear mine probably tighter than most and find straps bind after being on all night. But I do it for minimal leakage.

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snuzyQ +0 points · 26 days ago

Had you thought of switching to nasal pillows? These masks can and should be worn much more loosely. Ours are quite comfortable. We started out with the full face masks but found them impossible for numerous reasons and made the switch after the first 5 months on CPAP. We've never looked back. I was worried about the nasal pillows because I had been a lifelong mouth breather. From the first night of using my new mask, I found the feel of having pressure escape when I opened my mouth was very uncomfortable and I closed my mouth to avoid that uncomfortable feeling. My brain was very quickly trained to close my mouth while I sleep. I get through the night with minimal to no leakage at all. Also, I found posts to the forum during that time (6 years ago) that offered other very helpful techniques for keeping the mouth closed at night and all without using physical means such as chin straps, etc.. I'm truly amazed at how pliable and powerful our minds are. Happy 'pappin' to you.

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wiredgeorge +0 points · 25 days ago Sleep Enthusiast

Nasal or nasal pillow masks are not really suitable for high pressure therapy settings. Mask type is sometimes limited for high pressure prescriptions. If Cyberslayer is having a hard time with mask SIZE due the mouth and nose variation, he could look at a mask like the Amara View. It has a size but that size pertains mostly to the mouth area as it fits up under the nose and is considered a full face mask without covering the nose.

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Sierra +0 points · 23 days ago Sleep Commentator

EPR is a ResMed term for Expiratory Pressure Relief. It is simply a reduction in the mask pressure when you exhale compared to when you inhale. In theory the setting refers to the number of cm of water pressure difference. To the CPAP user it usually feels subjectively good. The higher pressure on inhalation helps you get air in, while the lower pressure on exhalation makes it easier to get air out. It sounds like a good thing, so why wouldn't you always use it? This is where it starts to get complicated, but my resolution of it is that for most, but potentially not all people, obstructive apnea occurs on the exhale side of the cycle, not the inhale. So, if you have your machine set at 12 cm for example, and the EPR at 3 cm, you are only getting 9 cm pressure on the exhale cycle and that is your effective treatment pressure preventing obstructive apnea on exhale. And, at the same time your mask has to seal against the 12 cm pressure. Now if your machine is in APAP or AutoSet mode it will increase pressure to compensate for the EPR providing your maximum is high enough. If it is not, then treatment is going to be limited, and your AHI is likely to go up.

I use the AirSense 10 Autoset machine, and this is how I use EPR. I have found that I can run about 1.5 cm lower pressure and get the same effectiveness with the EPR off compared to having EPR set at 3. But, I still use EPR set at 3 during the Ramp cycle of use. I find the EPR of 3 makes the CPAP more comfortable when I am awake and trying to go to sleep. I set the Ramp start pressure fairly high (8.4 cm currently for myself), so it cycles between 8.4 cm on inhale to 5.4 cm on exhale during the ramp period. I use the A10 Auto Ramp feature, which holds the pressure at that level until it senses you are asleep, instead of the gradual ramp up for a set period of time. And, there is a setting to make EPR effective on Ramp Only in the Clinical Menu.

This said, is turning EPR off effective for everyone? Well for my wife not so much. She seems to get less benefit than I do from turning it off. Must have something to do with when/how she gets apnea. She seems to gain less than 1 cm by turning it off.

What about A-FLEX or C-Flex used by Dreamstation. Well, it seems they don't really reduce the pressure on expiry although they use the same 1, 2, 3 setting scheme. They just shape the pressure response a bit on expiry, but the average pressure is not really reduced any significant amount. So, while I have not used those machines, I kind of think the setting may be a bit of a comfort perception thing. If you try it and like it, then use it. But, it probably does not change the treatment effectiveness like it does on the ResMed machines. Those are just my conclusions. Here is a link to an article on the differences between the machines in this feature.

Comparing expiratory relief in different CPAP machines

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sleeptech +0 points · 22 days ago Sleep Commentator

C-Flex and A-flex do reduce the pressure on expiration, but not always by the same amount as is the case with EPR. I cannot remember the details of exactly how C-Flex differs from EPR (one of the reps explained it to me recently) but it is effectively the same thing and I can testify from first hand experience that it can cause the same problems as EPR. Use with caution and consultation.

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Sierra +0 points · 22 days ago Sleep Commentator

There is a link below to a good article/study on the different techniques. I think the short story is that EPR is a fixed pressure drop equal to the setting, but does not allow pressure to drop below 4 cm, so it gets limited with low mask pressures. The Flex pressure drops are modified to be flow dependent and more drop is allowed at higher treatment pressures. The net result seems to be that Flex has a drop, but it is less than EPR, except for the P-Flex, and it has less of an effect on AHI.

Pressure-Relief Features of Fixed and Autotitrating Continuous Positive Airway Pressure May Impair Their Efficacy

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Sierra +0 points · 13 days ago Sleep Commentator

Here are a couple of real life examples of using EPR compared to not using it.

On my AirSense 10 AutoSet I adjusted pressure over time to do the best I could with an EPR of 3. To get a technically acceptable but poor AHI of about 4 I needed a maximum pressure setting of 15 cm. Now over time with EPR set at 3, but acting only during the ramp (set on auto) period of time, I have managed to get my maximum pressure setting down to 12 cm. While my AHI is still not super great because I have central apnea issue, I still have gotten it down to the 2.4 range, with the lower pressure of 12 cm. If you look at obstructive apnea events only, I do much better, with my last night actual scoring at zero for OAs! After I go to sleep I don't find it hard to exhale against 12 cm of pressure.

My wife uses a ResMed S9, and has been using it over 3 years now. I tried some time ago to convince her to stop the EPR, but she said she did not like it. So up until a couple of weeks ago she was using a maximum pressure setting of 15 cm and an EPR of 2 (that was our compromise a while ago), and getting an AHI of 1.6. While she started with a diagnosed AHI in the 70's and more than double my diagnosis, she gets much better AHI's as she has almost no centrals. Two weeks ago I convinced her to try the no EPR route again. I set her machine at EPR 3 but ramp only, with a maximum pressure of 14. Her average AHI to date with this setting is 1.1, and she even got a zero AHI in the past week. So far, my wife has not complained this time about exhaling against 14 cm of pressure. Now if she stops getting nights with zero AHI the discussion may be back on again!!

So, I gained the full 3 cm of pressure reduction with the elimination of EPR during the sleep period. My wife gained 1 cm reduction with a 2 cm change in EPR. So, it seems the hit from EPR can be a bit of an individual thing.

On the issue of getting more oxygen due to the high pressure during inhale compared to exhale, I am not so convinced. For sure it is real, but I have to question the magnitude of it. Why? The amount of oxygen in air is determined by the absolute pressure of the air, not the relative or gauge pressure that we use in CPAP. At sea level using CPAP units of pressure the absolute pressure is 1033 cm of water. So if we make an EPR 3 cm change in pressure that changes the oxygen content in the same volume of air by 3/1033 or 0.3%. Not a big number. And to put it in context our weather is changing our actual atmospheric pressure in the order of 35 cm of water from a high pressure event to a low pressure event. That means oxygen content is changing just due to weather as much as 35/1033 or 3.3%. That is a much higher impact than using EPR.

That said, I encourage using EPR, but only during the ramp period where it does not compromise the treatment of apena when you are sleeping.

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AliceMeier +0 points · 13 days ago

Hi, I am using RESMED airsense 10. Please excuse my English. In German fores it is said to raise the EPR in order to avoid the air to be going into the stomach. Does that really help?

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Sierra +0 points · 12 days ago Sleep Commentator

I understand excessive air in the stomach is called aerophagia, and does occur in some CPAP users. I have not had any issues with it while using EPR and when not using it, so no personal experience. I will give you a link to read about it. There seem to be many potential causes and many potential ways to address it. Pressure can be too low, causing you to gulp air. Pressure can be too high, forcing excess air into your stomach. With respect to using EPR, it is suggested that raising it, or setting it at 3, not zero can reduce pressure during exhale and may reduce the swallowing of air. While that might be true on a fixed pressure CPAP, an Auto CPAP like the AirSense 10 AutoSet, may respond to the reduced air on exhale if it produces any apnea events or flow limitations. It increases pressure to compensate, and effectively defeating the EPR.

In short, complex. The easiest thing to do is try using EPR at 3 and compare it to EPR turned off. Watch what happens to your AHI scores. Do they get worse? If this is not an obvious solution you probably should go back to your provider to see where you stand with pressures and what could be changed to reduce the aerophagia. Suitability of your mask should also be reviewed.

Aerophagia Causes and Resolutions

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Turquoiseturtle +0 points · 12 days ago

Thanks for all the info on EPR. I had. No idea. . . Have been on CPAP for just over 2 years (air sense 10, nasal pillows). At diagnosis, my AHI, ranged from 5-8. Wth treatment it was about .5, until this past month. Now it is jumping all over the place. Several in the 4-6 range. AHI is now 1.6 for the last 30 days. I had a similar spike last year, only lasting a couple weeks, and my provider was not concerned, as AHI was still just below 1.0. Early on the central AI was about 50% of the total AHI. Now it is closer to 90%, if I am understanding the numbers correctly. Today's reading for last 30 days AHI 1.6, central AI 1.4. I turned off EPR, and will see how that goes.

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Sierra +0 points · 12 days ago Sleep Commentator

Central apena do not respond well to APAP treatment, but turning off the EPR is certainly worth a try. Your machine simply ignores CA events and does not respond to them.

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Turquoiseturtle +0 points · 6 days ago

Tried EPR off a couple nights. Did not like the feeling. Also no change, event wise. So it is back on and I see sleep Doc soon.

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Sierra +0 points · 6 days ago Sleep Commentator

I have similar issues with central apnea. I seem to go in stretches when my AHI and CA's are low. Then I go on a stretch where I get an AHI over 5. Last night I actually hit 7.5. I don't think they are going to get very concerned about it until you start to average over 5 for AHI.

On trying EPR off, I would focus on the obstructive events. Compare the number of OAs you get with and without EPR. My thoughts are that if I can get OA down then I can live with higher CA.

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coimeten2099 +0 points · 7 days ago

EPR is fixed 1 2 or 3 cm H2O on entite exhalation. A-Flex\C-Flex 1 2 or 3 depends on the amount of inhalation. Big breath it the relief is bygger, small inhalation small relief. But nerver more than its value 1/2/3 cm. And c-flex a-flex differs because it doesnt relief more than half of the exhalation cycle. After half exhalation it goes back to initial pressure that was at the start of the inhalation. This prevents apneas that can occour if u use pressure relief on entire exhalation

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Sierra +0 points · 6 days ago Sleep Commentator

I believe the other difference in the two methods is that the Flex methods use a timed predictive technique in the switching between the two pressure levels. The EPR method is based on flow. It tries to follow what you want to do. There are pros and cons to each method.

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coimeten2099 +0 points · 6 days ago

The EPR is static on 1 2 or 3 cm not flowbased like Flex

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Sierra +0 points · 6 days ago Sleep Commentator

Yes, I understand that Flex uses the flow rate, and set pressure to determine how much and when to cut back or increase EPAP during the exhale portion of the cycle. What I am talking about is the "decision" by the machine to make the switch from EPAP to IPAP or back. I believe Flex tries to predict using timing when you are going to breath out or in, while ResMed uses flow rate. I didn't see flow change for 1 sec so it is time to switch kind of logic.

I used a Fisher and Paykel machine in my trial period, and while they are not very forthcoming on how they do the switch from IPAP to EPAP, I strongly suspect it is a timing based logic similar to Flex. I often found the machine trying to force me to start a new breath when I really didn't want to. It wasn't a major effect, but it was noticeable. I complained about it, and I think all they did was turn down the EPR. I find the ResMed AirSense to be totally unobtrusive in making the switch when EPR is on and even set at 3.

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coimeten2099 +0 points · 5 days ago

Are we talking Bipap/Bipap-Auto and BiFlex? Or do you relate inspiratory flow as IPAP and EPAP as expiratory because u set Flex. In a APAP u dont talk about EPAP and IPAP. Auto -pressure with pressure relief but i understand what u mean. Resmeds algoritm is more aggressive and Philips algoritm is like u say waiting for the patients breath.

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