problem with automatic pressure compensation

I FINALLY solved the problem that was plaguing me with my CPAP. I use the ResMed AirSense 10 AutoSet. I was started off with the 4 to 20 setting. The pressure could get so strong my ears would pop. I started with the Nasal CPAP mask. I went to my first follow-up visit and asked them to turn down the pressure. Because I wasn't having leakage errors I moved to the "Nasal Pillows" mask. They turned down the top pressure to 15.

The problem I was struggling with was the difficulty of breathing out. It was causing me to panic.

I'm technical (computers and electronic design) so I was trying to understand the automation software of the CPAP unit. Something just didn't make sense. I had gotten to where I could do a 2 hour session if I was very careful. My wife works the late shift and I usually wake up to welcome her home (and pee). But then the attempt to launch another session was a disaster. I had cranked up the "ramp" to 45 minutes. I couldn't escape the feeling that I'd only get one ramp. That the 2nd session would pick up where the first session let off. (This was not the case but let me explain the confusion.)

The first problem was the pressure indicator on the screen. I never saw it go higher than 4. The backlight shuts off so quickly I didn't ever even see it step to 4.1. And yet, the pressure was VERY high! That didn't make sense. I stopped trusting the display.

(Sorry I'm so verbose.)

I was coming very close to failing. Half of my friends have failed and given up. I was DETERMINED not to. With the struggle I wasn't getting good sleep and that was effecting my mood and health, frankly. I went back for another follow-up visit. I was going to demand they turn down the pressure again. They had more detailed data than the information you get from the ResMed myAir website. They showed me from the data that the pressure never went past 9. Huh? If that was the case, turning down to 10 wasn't going to help.

Let me "cut to the chase" Here's what can happen. There is a "feature" that tries to compensate for leakage by turning up the pressure. That increased pressure is NOT indicated on the display and it goes up (seemingly) all the way! I'm guessing the red, frowning face will eventually indicate massive mask leakage. But I was furiously trying to "reset the ramp." (Confused.) I even pulled the power on the unit in an attempt to make it reset.

The biggest problem was I didn't trust the unit anymore. It sure as hell wasn't doing 4.0 pressure. The key word in that last paragraph is "eventually." Even the "hi res" data the doctor and technician can see is averaged. Peak events are not recorded. (Many times I'd stop the intense pressure before the red, frowning face came up.)

I had to go through the process a number of times to show them the "big puff" as I was calling it. That's what I call the "automatic pressure compensation" run-away.

Bottom line. Simply turning the unit off and on DOES reset the ramp. Make sure the mask is right at the beginning and that first 4.0 gets breathed in and gently out.

Fist of all, please fill out your profile in case anybody else with the same machine had the same specific issue. You did mention the machine in the text, but it's best placed in the profile.

Next, it's not 100% clear, but it sounds like your automatic leak detection is detecting bogus leaks thus delivering pressure much higher than is indicated in the stats. I don't know if there's any way to suppress leak compensation besides using a machine so old that it doesn't have this feature.

BTW, if you want to use the ramp at the beginning of the night but not during a potty break, just leave the machine running. You'll probably also have to disable the auto-off feature for this to work correctly.

Unless the ramp is making you more comfortable, there's no reason to leave it engaged. This is strictly a comfort feature. If it's causing discomfort, or even if it's "neutral," there's no reason to use it.

I'm not responding to this to convince schaferob, simply to set the facts straight, because all the conclusions below are wrong.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

I was started off with the 4 to 20 setting....
I had cranked up the "ramp" to 45 minutes...

The ramp has no effect when your starting pressure is 4.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

That the 2nd session would pick up where the first session let off.

Well, yes, if you were still at four, the machine doesn't go any lower than 4, but 4 is where it started, every time, if your pressure was 4-15.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

The first problem was the pressure indicator on the screen. I never saw it go higher than 4. The backlight shuts off so quickly I didn't ever even see it step to 4.1. And yet, the pressure was VERY high!

No, it wasn't. The pressure was 4, and it STAYED at four till there was a breathing event.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

(Sorry I'm so verbose.)

uh, huh.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

t the pressure never went past 9. Huh? If that was the case, turning down to 10 wasn't going to help.

Well, yes, this is correct.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

Let me "cut to the chase"

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

Here's what can happen. There is a "feature" that tries to compensate for leakage by turning up the pressure

This is 100% wrong. There is no such 'feature', machines DO NOT RAISE PRESSURE IN RESPONSE TO LEAKS. Point of fact, the machines will *REDUCE* pressure if the leaks are really bad.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

That increased pressure is NOT indicated on the display and it goes up (seemingly) all the way! I'm guessing the red, frowning face will eventually indicate massive mask leakage. But I was furiously trying to "reset the ramp." (Confused.) I even pulled the power on the unit in an attempt to make it reset.

No, you're 100% wrong. The display indicates the correct pressure. You couldn't "reset the ramp" because there was nothing for it to reset to, your machine was at 4cm pressure, and you didn't have your mask on properly,

Machines generate a flow of air, when that flow is impeded, that creates pressure, when you don't put your mask on properly, then more air leaks than what should be going through the mask vent, the machine has to increase the FLOW to compensate for the increased leakage. the bigger the leak, the more FLOW that has to be created to MAINTAIN the desired PRESSURE (4cm/h2o).

The way to get the FLOW to reduce is to SEAL YOUR MASK. The red frowny face means you were having very bad leaks.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

The biggest problem was I didn't trust the unit anymore. It sure as hell wasn't doing 4.0 pressure.

The biggest problem is that you had no idea what was going on, and you'd concocted a nearly totally wrong theory.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

The key word in that last paragraph is "eventually." Even the "hi res" data the doctor and technician can see is averaged. Peak events are not recorded. (Many times I'd stop the intense pressure before the red, frowning face came up.)

Again, no intense pressure, just your mistakes. The mask pressure trace in the data is updated 25 times PER SECOND.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

I had to go through the process a number of times to show them the "big puff" as I was calling it. That's what I call the "automatic pressure compensation" run-away.

Again, there is no such thing.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

Bottom line. Simply turning the unit off and on DOES reset the ramp. Make sure the mask is right at the beginning and that first 4.0 gets breathed in and gently out.

This is really the only correct thing in your post.

D.H. wrote: ↑

Fri Jun 29, 2018 10:21 am

Next, it's not 100% clear, but it sounds like your automatic leak detection is detecting bogus leaks thus delivering pressure much higher than is indicated in the stats. I don't know if there's any way to suppress leak compensation besides using a machine so old that it doesn't have this feature.

You blitering idiot, there is no such thing. Machines NEVER INCREASE PRESSURE DUE TO LEAKS!

D.H. wrote: ↑

Fri Jun 29, 2018 10:21 am

BTW, if you want to use the ramp at the beginning of the night but not during a potty break, just leave the machine running. You'll probably also have to disable the auto-off feature for this to work correctly.

moron.

You said your difficulty was breathing out...Your machine has an EPR function...Exhale Pressure Relief. This feature will only work at higher pressures. It will not work when the preesure is at 4. It can reduce the pressure when exhaling by 1,2 or 3. You seem to be making assumptions about your machine. Here is the Clinical Manual for you to read. https://sleep.tnet.com/home/files/resme ... -guide.pdf

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

I'm technical (computers and electronic design)

Good. So, quit relying on your doctor and quit using this low tech app

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

ResMed myAir

Even the "hi res" data the doctor and technician can see is averaged. Peak events are not recorded.

and learn to use

https://sleep.tnet.com/resources/sleepyhead
https://sleep.tnet.com/resources/sleepyhead/shorganize

Good luck.

palerider wrote: ↑

Fri Jun 29, 2018 11:35 am

D.H. wrote: ↑

Fri Jun 29, 2018 10:21 am

. . .

You blitering idiot, there is no such thing. Machines NEVER INCREASE PRESSURE DUE TO LEAKS!

. . .

Leak compensation indeed does cause the motor to blow harder (i.e. faster). If it's working correctly, the pressure delivered is the correct pressure after adjusting for the leak. However, if a bogus leak is "detected," then it could have the effect of delivering a higher pressure.

D.H. wrote: ↑

Fri Jun 29, 2018 4:13 pm

if a bogus leak is "detected," then it could have the effect of delivering a higher pressure.

What's a bogus leak? How could that happen?

Pugsy wrote: ↑

Fri Jun 29, 2018 4:26 pm

D.H. wrote: ↑

Fri Jun 29, 2018 4:13 pm

if a bogus leak is "detected," then it could have the effect of delivering a higher pressure.

What's a bogus leak? How could that happen?

How can any machine ever malfunction?

palerider wrote: ↑

Fri Jun 29, 2018 11:33 am

I'm not responding to this to convince schaferob, simply to set the facts straight, because all the conclusions below are wrong

now, of course, some first or second time poster will come in to tell you how mean and unfair you are being!

D.H. wrote: ↑

Fri Jun 29, 2018 4:13 pm

palerider wrote: ↑

Fri Jun 29, 2018 11:35 am

D.H. wrote: ↑

Fri Jun 29, 2018 10:21 am

. . .

You blitering idiot, there is no such thing. Machines NEVER INCREASE PRESSURE DUE TO LEAKS!

. . .

Leak compensation indeed does cause the motor to blow harder (i.e. faster). If it's working correctly, the pressure delivered is the correct pressure after adjusting for the leak. However, if a bogus leak is "detected," then it could have the effect of delivering a higher pressure.

You're full of cow manure. "bogus leak". You're gibbering garbage that will do NOTHING but confuse the issue for the OP.

DO SHUT UP, you ignorant fool.

D.H. wrote: ↑

Fri Jun 29, 2018 4:46 pm

Pugsy wrote: ↑

Fri Jun 29, 2018 4:26 pm

D.H. wrote: ↑

Fri Jun 29, 2018 4:13 pm

if a bogus leak is "detected," then it could have the effect of delivering a higher pressure.

What's a bogus leak? How could that happen?

How can any machine ever malfunction?

The one in DH's head has been broken for a long time.

schaferob wrote: ↑

Fri Jun 29, 2018 9:25 am

The first problem was the pressure indicator on the screen. I never saw it go higher than 4. The backlight shuts off so quickly I didn't ever even see it step to 4.1. And yet, the pressure was VERY high! That didn't make sense. I stopped trusting the display.

If you turn the knob one click, the display will turn on and show the current pressure. Probably pressing home or pushing the knob button will do this as well. As noted above - don't expect it to move from the low pressure setting while you're awake. Look at it whenever you wake up if you like.

I'm also new to this. I've got to admit that I went through the same sort of thing. My suspicion was that the machine was reaching upper pressure limit and never dropping back down. And it felt like very high pressure. What I just learned from palerider is that this was apparently me taking in that extra flow. And I wasn't "trusting the machine" either. I know this is not a good feeling. I called the dr's office and the tech looked at my data. First thing she said was "you've got too much mask leakage, these machines can't do their job with this much leakage" (at the time, I felt this statement came out of left field, and wasn't in any way related to my concern). Well, fixing this turned out to be key for me. Everything got easier. I've gotten in the habit of running the "Mask fit" off the menu every night right before I turn in (and keeping my beard trimmed). FYI- my AHI went up after fixing the leakage. So don't be surprised if that happens. The machine can't sort out what's what under these conditions, and stops recording events.

palerider wrote: ↑

Fri Jun 29, 2018 11:33 am

The biggest problem is that you had no idea what was going on, and you'd concocted a nearly totally wrong theory.

Been there.

djams wrote: ↑

Fri Jun 29, 2018 9:23 pm

I've got to admit that I went through the same sort of thing. My suspicion was that the machine was reaching upper pressure limit and never dropping back down. And it felt like very high pressure. What I just learned from palerider is that this was apparently me taking in that extra flow. And I wasn't "trusting the machine" either. I know this is not a good feeling. I called the dr's office and the tech looked at my data. First thing she said was "you've got too much mask leakage, these machines can't do their job with this much leakage" (at the time, I felt this statement came out of left field, and wasn't in any way related to my concern). Well, fixing this turned out to be key for me. Everything got easier.

The confusion between pressure and flow is a common one. Flow is the movement of a fluid (yes, air is a fluid), just not a very dense one). Pressure is what happens when that flow is resisted.

If you take the mask off, there's very little resistance, so the pressure drops down to near zero.. as a result, the machine ramps up the blower speed to create more flow, in an attempt to raise the pressure, even though that's impossible, due to no resistance... but, it doesn't know, and tries anyway.

The machines can generate a LOT of flow...many times what they normally create when your mask is on your face.

Most masks vent around 20 liters per minute at 4cm pressure. According to the manual, the air10 machine can keep that pressure with up to 180 liters per minute of leak.. So if you've got a truly massive leak, the machine can still maintain that 4cm pressure up through 180 liters per minute of flow... anything larger than that, and the pressure starts to fall off.

The fan in the cpap is constantly adjusting it's speed to maintain the exact pressure it's supposed to, when you've got a good seal, and you're breathing, the fan speeds up when you inhale, and slows down when you exhale. You can hear this if your put your ear up against the machine.... It does this, to maintain the pressure... therefore, the idea of the pressure going up with a leak... is just wrong.

palerider wrote: ↑

Fri Jun 29, 2018 9:38 pm

The confusion between pressure and flow is a common one. Flow is the movement of a fluid (yes, air is a fluid), just not a very dense one). Pressure is what happens when that flow is resisted.

If you take the mask off, there's very little resistance, so the pressure drops down to near zero.. as a result, the machine ramps up the blower speed to create more flow, in an attempt to raise the pressure, even though that's impossible, due to no resistance... but, it doesn't know, and tries anyway.

The machines can generate a LOT of flow...many times what they normally create when your mask is on your face.

Most masks vent around 20 liters per minute at 4cm pressure. According to the manual, the air10 machine can keep that pressure with up to 180 liters per minute of leak.. So if you've got a truly massive leak, the machine can still maintain that 4cm pressure up through 180 liters per minute of flow... anything larger than that, and the pressure starts to fall off.

The fan in the cpap is constantly adjusting it's speed to maintain the exact pressure it's supposed to, when you've got a good seal, and you're breathing, the fan speeds up when you inhale, and slows down when you exhale. You can hear this if your put your ear up against the machine.... It does this, to maintain the pressure... therefore, the idea of the pressure going up with a leak... is just wrong.

Fantastic explanation. Thank you. (Again)