On which parameter to play, when, why, with which result ?

I am a 2 month old Newbie and I am confronted with my first Oscar graphs.
Not easy ...
My hand is shaking ....

To improve the therapy, there aren't a million parameters to operate.
Unless I am mistaken, there are essentially 3 important ones: ERP, Min pressure and Max pressure.

To progress, I would be interested in having your input/experience, if it makes sense and has not already been done, regarding the following questions. Even if the answers are general and not mathematical:

for each one of these 3 parameters:

EPR
MIN Pressure
Max Pressure

Usually:
when, should I consider playing with this parameter?
To address what concern?
And, if I bring it up or down, what impact can I expect, on which OSCAR graph(s)/variable?

A great thank you in advance

I would first post an Oscar screenshot of your night so people have a baseline to go off of. You’re not wrong that those are important settings, but there are so many factors at play that they might not even need changed. Like leak rate, for example. Post an Oscar screenshot and we will be able to help a little more. Not me specifically, but there are a few here that are amazing reading charts.

Albatros wrote: ↑

Fri Dec 09, 2022 4:18 am

I am a 2 month old Newbie and I am confronted with my first Oscar graphs.
Not easy ...
My hand is shaking ....

To improve the therapy, there aren't a million parameters to operate.
Unless I am mistaken, there are essentially 3 important ones: ERP, Min pressure and Max pressure.

This is "true" only if the data is indicating that your AHI is still too high or you are still snoring or you are still having a lot of flow limitations.

If the problem is comfort, there's a lot more to play with and dial-winging the pressure settings and EPR might do nothing to address the comfort problem you are trying to fix.

And leak data is always important: If leaking is going on, that has to be taken into account if/when deciding to dial-wing the big three of Min Pressure, Max Pressure, and EPR.

To progress, I would be interested in having your input/experience, if it makes sense and has not already been done, regarding the following questions. Even if the answers are general and not mathematical:

for each one of these 3 parameters:

EPR
MIN Pressure
Max Pressure

Usually:
when, should I consider playing with this parameter?
To address what concern?
And, if I bring it up or down, what impact can I expect, on which OSCAR graph(s)/variable?

Of all your questions, the one I think has to be addressed first is: To address what concern?

In other words, effective dial-winging starts with describing the problem(s) you are trying to fix in language that is less vague than "I want to feel better" or "I want to optimize therapy".

You start with one or more specific problems you are trying to fix, and then make a decision of what setting(s) to play with. It does help, however, to only play with one setting at a time and to use each new change for several days before making further adjustments.

That said, the most general guidelines for dial-winging in my opinion are:

You usually play with min pressure and/or max pressure when the AHI is too high OR when you're still snoring OR if you still have a lot of flow limitations OR if you have a lot of clustering of events going on. Or if you are dealing with problems like severe aerophagia. Or (occasionally) if leaks are problematic. For most (but not all) of these problems, min pressure is usually the first thing to play with---provided that the max pressure is not set way too low. But there are a few cases where playing with max pressure first makes sense.

As for EPR: It's mostly a comfort thing: If you are having trouble exhaling against the pressure, you might as well turn it on and start with EPR = 3. You really only need to worry about EPR being set too high if you see a huge number of CAs in your data on multiple nights---one or two CAs now and then is not enough to warrant giving up the comfort of EPR. You also play with the EPR setting if you feel like the machine is "rushing" you to breathe, although whether turning EPR up or down or off in this case really depends on the sensation the person is experiencing and what the current EPR setting is.

I'll end by saying: Dial-winging without a specific problem in mind is not likely to be an effective way of optimizing therapy. You have to have a goal in mind before you start playing with the settings.

This sounds very similar to what I’m going into at the moment. I never messed with EPR very much, I did change it to 2 once, but felt very hard to breathe. The general consensus is that EPR is safe and fine to use and shouldn’t affect too much, other than clear airways. Never really had those so I just leave it at 3.

The issues I’m having is sleep continuity and aerophagia. I think I know my aerophagia pressure, so I’m trying to stay below that. I do have leaks in the night, which I think are the main reason I wake up. I think the cold air hits my lower lip or comes out of my mouth onto the pillow and it wakes me up. I also switch from side to back several times which usually results in a wake-up.

So, RobySue and Dog Slobber have been a huge help in getting me the right pressure settings. They both are very good at OSCAR deciphering, and can help you get started with that. But we would also need to know what mask/machine setup you’re using as well.

Go check out my recent thread titled “APAP vs cpap settings”. RobySue goes into vast detail about what each thing does and it helped me understand so much more about pressure. I had to read it twice to really grasp it.

Edit: RobySue, when you say mess with pressure settings when AHI levels are too high, is that just based on Oscar/ and the machines findings, or would it also include those you count by hand. In terms of Oscar and my pressure raises, my ahi rarely gets over 2, but if I went back and counted every cluster that I stopped inhaling for 10 seconds, it would probably be well over 4-5 per hour. I see a ton that are not marked but are clearly straight flat lines.

jlsmithseven wrote: ↑

Fri Dec 09, 2022 9:24 am

The issues I’m having is sleep continuity and aerophagia. I think I know my aerophagia pressure, so I’m trying to stay below that. I do have leaks in the night, which I think are the main reason I wake up. I think the cold air hits my lower lip or comes out of my mouth onto the pillow and it wakes me up. I also switch from side to back several times which usually results in a wake-up.

Do you have a heated hose? If so, then turning the temperature up on the hose might help the problem of cold air hitting your lips and waking you up.

Way back when in 2010, cold air coming through the exhaust vents of my Swift FX and hitting my chest and upper arms was a huge problem. I had no heated hose and didn't want to purchase one---it would have been 100% OOP at the time. Since our bedroom was cold, I took to sleeping in my husband's fleece robe. Now? I still sleep in his (old) fleece robe and he now sleeps in his newer fleece robe that Santa brought him many years ago to make up for the fact that I had stolen his robe in order to get some sleep.

Edit: RobySue, when you say mess with pressure settings when AHI levels are too high, is that just based on Oscar/ and the machines findings, or would it also include those you count by hand. In terms of Oscar and my pressure raises, my ahi rarely gets over 2, but if I went back and counted every cluster that I stopped inhaling for 10 seconds, it would probably be well over 4-5 per hour. I see a ton that are not marked but are clearly straight flat lines.

It would be useful to see some examples of what you are talking about posted in your own thread. Not every pause in breathing is a hypopnea or apnea. For example, it's not uncommon to hold ones breath when turning over in bed and that can show up as a flat line in the flow data that is sometimes not scored. But sometimes the algorithms for scoring events do seem to "miss" events that should be scored. But usually if there's a lot of that stuff happening, the AHI is a bit higher than desired (but not necessarily above 5) or there's still a lot of activity in the flow limitation graph. And then there's also the whole question of whether those missed events are obstructive or central or just part of SWJ----particularly if you are dealing with severely fragmented sleep in the first place.

But how much time to spend on trying to "correct" the machine's AHI computation is really in the eyes of the beholder. I no longer attempt to go through my flow data every day to try to "catch" the things that the machine didn't flag (for some reason) and I no longer attempt to try to figure out whether every single event that is flagged is "real" or not. I may do it when I'm trying to help newbies, but when that happens, I'm pretty much looking for something in my own data to post in order to teach others something.

And you can have Oscar do some of that work for you by using the Custom User flags under the Oscar preferences:

Thank you! Yeah, don’t want to sidetrack the OPs questions but I think their situation is similar. I do have a heated hose, the issue with that is, if I go to a higher temp, I need to change the humidity as well. Seeing as my room gets colder as the night progresses (baseboard heat tries to keep up), it never really works. I’ve tested multiple humidity and heat settings and it seems the auto works just good enough to keep it from pooling with water (already woke up to being waterboarded, so not really trying to have that again).

jlsmithseven wrote: ↑

Fri Dec 09, 2022 11:04 am

Thank you! Yeah, don’t want to sidetrack the OPs questions but I think their situation is similar. I do have a heated hose, the issue with that is, if I go to a higher temp, I need to change the humidity as well. Seeing as my room gets colder as the night progresses (baseboard heat tries to keep up), it never really works. I’ve tested multiple humidity and heat settings and it seems the auto works just good enough to keep it from pooling with water (already woke up to being waterboarded, so not really trying to have that again).

I have cold bedroom--temp is roughly 60 to 62 in the winter. And I keep my humidifier maxed out at 8 on the AirCurve with the heated hose set at 65F. And for years I used a PR DreamStation without a heated hose and the humidifier set to "Classic 5"---the max setting. And while I do get some gurgling, lifting the hose to let the water run back towards the machine fixes it.

I do, however, have the hose in a hose cozy and I run the hose under the blankets next to my body and I naturally sleep with my head (and hence the mask) under the covers. That's the only explanation I can come up with for why I have so few problems with rainout issues.

Albatros wrote: ↑

Fri Dec 09, 2022 4:18 am

for each one of these 3 parameters:

EPR
MIN Pressure
Max Pressure

Usually:
when, should I consider playing with this parameter?
To address what concern?
And, if I bring it up or down, what impact can I expect, on which OSCAR graph(s)/variable?

You want formulas to optimize your therapy. It's best to learn by doing. If you post an OSCAR (or sleepHQ) chart and get comments, you will start to learn how to optimize by practical experience.

If you post a chart, do it in a new thread because this one has been hijacked.

Albatros wrote: ↑

Fri Dec 09, 2022 4:18 am

If you post a chart, do it in a new thread because this one has been hijacked.

Did not mean that sorry, just wanted to give a little insight since I am also doing similar things. Just thought it might be nice for OP to read other thread, then come back here.

Agreed!

Albatros wrote: ↑

Fri Dec 09, 2022 4:18 am

for each one of these 3 parameters:

EPR
MIN Pressure
Max Pressure

For most people Max pressure should be left at 20 and ignored... only in very specific cases (aerophagia, and *possibly* severe treatment emergent CSA should the max be lowered, all you're doing by dicking around with max pressure is possibly preventing the machine from doing it's job.

Albatros wrote: ↑

Fri Dec 09, 2022 4:18 am

Robysue:
thank you for your remarks.
Could you please elabore about your 4 lines guidelines above ?
Why start with the min pressure, in the cases you are mentionning and how ?

I'm not going to answer for RobySue, but I think min pressure is very important because if you have APAP, the pressure will raise, then work down toward your min pressure all night. If the min pressure is too high, the extra air might get into your stomach (aerophagia), or it could create un-necessary leaking. Basically want to have that min pressure just enough that it keeps your airways open, but in the event they close, the machine will go to work.

An easier way to think of that maybe is take a thin balloon. If you blow it up to a certain level (min), then continue raising it it gets bigger and eventually can't hold air anymore. But if you start out that balloon at a lower level, you can raise it much more without it popping (aerophagia, nowhere else for the air to go). Just thought this out in my head first thing in the morning. Correct me if I'm wrong please!

Albatros wrote: ↑

Sun Dec 11, 2022 5:12 am

robysue1 wrote: ↑

Fri Dec 09, 2022 7:29 am

You usually play with min pressure and/or max pressure when the AHI is too high OR when you're still snoring OR if you still have a lot of flow limitations OR if you have a lot of clustering of events going on. Or if you are dealing with problems like severe aerophagia. Or (occasionally) if leaks are problematic. For most (but not all) of these problems, min pressure is usually the first thing to play with---provided that the max pressure is not set way too low. But there are a few cases where playing with max pressure first makes sense.[/b]

Robysue:
thank you for your remarks.
Could you please elabore about your 4 lines guidelines above ?
Why start with the min pressure, in the cases you are mentionning and how ?

If the AHI is too high or you are snoring or you have a lot of clustering of events, you start with min pressure because the min pressure should be high enough to prevent most of your apnea from happening during most of the night. When the min pressure is set high enough to prevent most of your apneas/hypopneas/etc from occurring, the machine does not need to increase the pressure as far when something does happen that triggers the need for more pressure.

In other words, setting min pressure high enough means the pressure swings (which can be troublesome to some people) are not as wide and the time needed to raise your pressure to an effective level when you do flip on your back or start a REM cycle (or both) is minimized. And because the machine can more quickly get up to the pressure you need when your apnea is at its worst, there's a much better chance that the machine will be able to "break up" a long cluster of events after the first few events occur.

Snoring indicates a compromised airway that is in danger of collapsing. It also can wake your bed partner. And it can wake up the snorer as well. Hence, in a formal titration study, the tech will usually increase pressure in the presence of snoring even if no OAs or Hs are taking place. Again, the idea is to have the minimum pressure sufficiently high to prevent most of your snoring so there is less need for the machine to respond with a really steep sudden increase in pressure when it detects snoring and the snoring is not responding to more modest increases in pressure.

Flow limitations are more complicated. To give you a basic understanding of what I'm going to say, I want to review the Philips Respironics BiPAP Auto algorithm before starting since it does a slightly better job of what mimicking what goes on during a bi-level titration, at least as my understanding of bi-level titration. (The Resmed VAuto algorithm is much less complicated.) On a PR BiPAP Auto, the pressure support---i.e. the difference between IPAP (inhalation pressure) and EPAP (exhalation pressure) is not fixed. And this allows the PR BiPAP Autos to increase only the IPAP or only the EPAP or increase both at the same time. Loosely speaking, a PR BiPAP auto increases EPAP (but not necessarily IPAP) when the machine detects snoring and OAs. And a PR BiPAP increases IPAP (but not necessarily EPAP) when the machine detects flow limitations, RERAs, and hypopneas. When IPAP is increased and EPAP is left alone, that effectively increases the PS setting. (Min PS and max PS control how much the PS can vary. When PS is at the min PS setting, that will force the machine to raise both EPAP and IPAP when EPAP needs to be increased; when PS is at the max PS setting, that will force the machine to raise both the EPAP and IPAP when IPAP needs to be increased.

So if there are still a lot of flow limitations in your data, there are two things that can be tried: If EPR is not at its max setting of 3, turning it up to 3 sometimes is enough to smooth out the flow limitation curve. Sometimes, however, a modest increase in min pressure will smooth out the flow limitations. (Some sleep labs will continue to try modest increases in pressure on a CPAP titration when flow limitations remain in the flow.)

But, at the same time, some people's upper airways don't get the memos about how flow limitations are supposed to work. There are people who wind up getting more flow limitations if the pressure is too high. There can also be some structural problems in the nose and upper airway that trigger flow limitations to be detected regardless of what pressure is used simply because those flow limitations are not being caused by an airway that is in danger of collapsing. So there's a lot of learning about your own data over time when you are looking at activity in a Resmed flow limitation graph.

As for leaks: The smaller the range of pressures that your machine uses over the course of the night, the less likely it is that a pressure increase will cause the mask to spring a leak. In other words, if you fit a mask at relatively low pressure (somewhere between 4 and 8 cm) and your machine regularly has pressure peaks up near 14-16cm, then it's not uncommon to find yourself dealing with leaks when at high pressure. Increasing the min pressure can make it easier for the mask to stay sealed once the higher pressures are reached.

In terms of numbers: If you decide to increase min pressure, the new min pressure should be set about 2 or 3 cm below what your 95% pressure level where that 95% pressure level is computed over at least a week's worth of data. It's important to understand that once you increase your min pressure, it's not uncommon to see the 95% pressure level go up a bit. That does not automatically mean another bump in min pressure is needed: If your current min pressure is working---i.e. your AHI is low, you're not snoring, your flow limitations are "decent enough" and you are waking up feeling rested, there is no need to increase the min pressure just because it's more than 3cm below what your 95% pressure level is.

Now on to talking about max pressure.

As palerider indicated, for many people it's perfectly fine to just leave max pressure = 20. That allows the machine full freedom to increase the pressure as high as it thinks it needs to go in order to prevent all the components of obstructive sleep apnea from happening.

But again, not everybody's body got that memo.

When is it reasonable to cap max pressure? The easiest way of answering that is: When you have problems at higher pressures. There are two main problems people can encounter with higher pressures: Aerophagia and pressure-induced centrals.

Aerophagia
If you have problems with painful aerophagia, capping max pressure is usually needed to prevent the aerophagia. In other words, for folks with aerophagia problems, there's a delicate dance involved in finding a max pressure that is high enough to do a decent (but not perfect) job of preventing most of the obstructive stuff from happening, but at the same time is low enough that you are not waking up feeling like you swallowed a basket ball. For folks with aerophagia, sometimes you just have to tolerate having the machine bump up against max pressure for extended periods of time even though this can mean a few more OAs or Hs or snoring. It's important to remember that the real goal of xPAP is not a super-low AHI; the goal of xPAP is to wake up feeling rested and refreshed each morning. And that's really hard to do if you wake up in pain from aerophagia multiple times a night.

It's also worth remembering that some people who start out with aerophagia problems are lucky and their bodies eventually figure out ways to tolerate more pressure with time. In other words, sometimes when aerophagia raises its ugly head you do need to temporarily settle for a max pressure that leaves you with too many OAs and Hs getting through the xPAP defenses. And then after getting the aerophagia under control, you can start increasing the max pressure bit by bit until the machine can go up to where it needs to go to prevent the worst of apnea when you need the additional pressure.

And it's also worth remembering that a few really unlucky people (like myself), run into aerophagia problems when the min pressure is set where it really ought to be set. When that happens, you basically have to start with a really low minimum pressure setting, even though it will probably allow too many events to happen. And once the aerophagia is under control, you start slowly increasing the minimum pressure until you've got most of the apnea under control.


Pressure induced centrals
Pressure induced centrals are a rarer problem, but at the same time, a more difficult problem to solve than aerophagia. The problem is that when some people start xPAP, if the pressure is too high, their ventilation with the xPAP can blow off too much CO2 with the exhalations. This in turn reduces the respiratory drive---the trigger for inhalation is the concentration of CO2 in the bloodstream. When the respiratory drive becomes too low, your brain stops sending the signal to inhale and a central apnea results. The CO2 builds up, you start breathing again, but the extra ventilation caused by the xPAP pressure causes too much CO2 to be blown off and the respiratory drive again is suppressed. And at its worst, you wind up with a whole string of CAs.

From what I've read, problems with pressure induced centrals are more likely to emerge at higher pressures---i.e. they are usually not a problem until the pressure is on the high side of 10cm. (The old pre-2010 Resmed S8 machines would not automatically increase pressure for OAs and Hs if the pressure was already above 10cm.)

Sometimes pressure induced problems (that are central in nature) don't have a nadir that goes all the way down to a CA. In other words, sometimes you might see a whole string of Hs or things that look like they ought to be scored as Hs, but aren't scored because there is no flow limitation. If there are flow limitations being scored and hence a string of Hs being scored, the pressure increases caused by the Hs & flow limitations make things get worse instead of better (if max pressure is set to 20 and the machine can just keep increasing the pressure.) When max pressure has been set and the machine is running at max pressure with a bunch of Hs being scored, it can be quite difficult to tease out whether the problem is that the max pressure really does need to be increased to address an obstructive problem or whether the problem might be more central in nature. That's when folks like Rubicon can provide really critical insight into what's going on.

And it's important to note: When we're talking about pressure induced centrals, we're not talking about a few events over the course of the whole night. And we're not talking about clusters of CAs scored just as you are falling asleep at the beginning of the night or just before you wake up in the morning. We're talking about a whole lot of events (i.e. the CAI is usually above 5 all by itself) and the events often occur in strings or clusters during times when you are actually asleep.

Minor problems with pressure induced centrals are often addressed with patience: For many people with pressure induced centrals the problem resolves itself in a few weeks as the body learns to adjust to the added ventilation from breathing with the xPAP pressure.


A final note
Because there are a few potential problems with leaving max pressure set to 20cm, some people are more comfortable setting max pressure about 2-3 cm above their 95% pressure level. That usually provides the machine with plenty of room to increase the pressure to address the apnea when it's at its worst, but at the same time, it will prevent the machine from continuing to increase pressure just because the flow limitation curve is not smoothing out or the breathing becomes a bit unstable due to blowing off too much CO2, but the machine misinterprets what's happening as obstructive rather than central in nature.