Great AHI But Difficulty Breathing Question

[Stewart194]

I've had my ResMed Air Curve 10 BiPap machine for almost a year. My AHI is always less than 1.0 these days, I have a mask I really love with no leaks, I wake up feeling pretty great, etc, etc.

But I feel like I'm trying too hard when I breathe in. Like I should be assisted more by the machine when I inhale. Once I'm asleep I don't notice it or feel that way...mainly just when I put the mask on and begin trying to go to sleep. It feels like I'm restricted when breathing in.

The settings are set to Auto which I found were much better than the Max and Min settings recommended by my sleep study people. (My AHI improved instantly when I set it to auto)

Is it possible that I need to reevaluate these settings even though my AHI is fine? Could I possibly not be getting enough oxygen with these settings and still have a great AHI?

Thanks in advance for any advice you can give me!

[Stewart194]

Forgot to mention...

My original Settings were Mode = VAUTO, Max IPAP = 14, Min EPAP = 10, PS = 2.0 which did not work well for me. I was getting consistent AHI readings of 4, 9, 11 & 22.

The new Settings that have been working well for me are Mode = VAUTO, Max IPAP = 25, Min EPAP = 12, PS = 2.0. I instantly started getting AHI readings of 2.0 and below...and once I found the correct mask and eliminated the leaks they've been under 1.0 every night. (According to Sleepyhead Software and the built in ResMed software)

[john5757]

Sounds like your starting pressure is low.

[Pugsy]

Are you using the ramp feature?

[Stewart194]

I'm not using the ramp feature. It is turned off.

One thought I just had, I have not replaced my air filter for a while. Could that be it? I wouldn't think so though.

[Stewart194]

Should I bump up my minimum setting up to 14 or 16 possibly and give that a try?

[Pugsy]

With your current settings the starting pressures are 12 EPAP and 14 IPAP.
PS is the difference between EPAP and IPAP.
So the discomfort is initially and not during the night where with IPAP max set to go to wherever it needs to go...always with EPAP 2 CM behind it.

I doubt the filter is the problem but wouldn't hurt to change it if it looks dirty or has been quite a while.

Since ramp is turned off then ramp's lower pressures can't be the problem but you might watch the machine and make sure that you are doing 12/14 with each inhale and exhale. Lower pressures can sometimes cause people to have difficulty breathing...they feel like their breathing is stifled. We are talking pressures in the 4 to 6 EPAP/IPAP range and not the 12 you are starting with.

I would suggest trying to vary PS a bit to see if that helps. Leave EPAP at 12 and maybe try 3 or 4 PS (don't go higher than 5 PS though).
Do this while awake and under no pressure to be going to sleep. Just test it out to see if it makes breathing easier and more "natural" feeling. While PS of 2 offers some comfort...3 or 4 might offer a lot more comfort. I have used your type of machine and my EPAP started at 10...I have tried PS of 2, 3 and 4...and I found that 4 was a lot more comfortable than 2.

[palerider]

my first thought, based on the way the problem was described, was to increase PS.

[Pugsy]

my first thought, based on the way the problem was described, was to increase PS.

I agree.

I don't think increasing minimum EPAP will do anything except probably make things more difficult and if the AHI is nice and low there's no need to increase min EPAP.

There's a reason that bilevel titrations typically start with 4 cm PS. It's the most commonly used PS setting with the "regular" bilevel machines.

[Stewart194]

Thanks everyone. I went to set the PS to 4.0 today and discovered that the current settings were set to Max IPAP = 25, Min EPAP = 12, and PS = 2.0. Does that change anything? (I did raise the PS to 4.0) Also, my machine is set to VAUTO...but I'm not sure what that means exactly.

Also, I'm starting to think that maybe my sinuses are the problem and not the machine. I was talking about it with my mom over Thanksgiving and she gave me some nose spray to try. I had never used that before but it totally opened up my nasal passages and I did not notice the restricted breathing at all.

[Pugsy]

my machine is set to VAUTO...but I'm not sure what that means exactly.

Max IPAP = 25, Min EPAP = 12, and PS = 2.0. Does that change anything?

VAuto is just the mode where the pressure will auto adjust as it senses the need within whatever parameters that have been set.
Minimum EPAP...that's the minimum Exhale pressure.
PS is the difference between inhale and exhale
Maximum IPAP ...that's the most that IPAP can go to.
When you are using the current settings above...the starting pressures when you first turn the machine on will be
12 exhale plus the 2 PS to make 14 inhale...then as the night goes on and you go to sleep the machine will auto adjust the pressures as it senses the need...if it thinks it needs more EPAP then it will increase EPAP which will push IPAP up.
If it thinks it needs more IPAP it will increase IPAP and pull EPAP up with it. All the time maintaining the 2 cm difference.
So if it thinks you need 17 EPAP then IPAP will be 19. If it thinks you need 21 IPAP then EPAP will be 19 cm.

Since once we get to sleep we don't notice the changes and most will sleep through whatever the machine wants to do what we want to do is make it comfortable while awake when you first start the machine so that you don't feel like you are fighting the machine to exhale. It's a bit of a workout to exhale against that 12 cm pressure. That's where PS comes in handy. The difference between inhale and exhale (that drop) is what makes things easier in terms of comfort. For a lot of people using 14 inhale and 12 exhale is a whole lot easier than simply doing straight 12 cm (like fixed cpap).
It's the difference between inhale and exhale that makes for more comfort and we need to be comfortable if we ever hope to go to sleep.

Since you aren't so comfortable with 2 cm difference...that's why we suggest a little greater difference because for some people it can make a huge difference in terms of comfort.
I can do 12 cm straight cpap...it's a bit of work but I can do it and many people do a whole lot more without any drop in exhale to help them out.
I can do 12 cm exhale and 14 cm inhale easier than I can do straight 12 cm. I know it sounds weird but it's true. That 2 cm difference makes things a whole lot easier.
I can do 12 cm exhale and 16 cm inhale even easier. Again I know it sounds weird but the bigger the difference the easier it is in terms of comfort.
It's not usually recommended that people exceed 5 cm PS unless advised directly by a doctor for some reason because if the PS is too high then it can lead to too much CO2 washout which can lead to centrals. Now there are some situations where higher PS is advised (maybe some lung disease or something going on) but for normal healthy people...keep it below 6 cm unless a doctor is involved. Besides...too much PS causes loss of comfort anyway.

In time you might get to where you don't need as much PS in terms of comfort. We do get used to the pressures no matter what they are but some people just have a little more trouble getting used to them than others.
You gotta get the sleep first though...so do whatever it takes to make things more comfortable for you so that you can fall asleep easily...then the machine goes about doing its job and you sleep right through it.

[Stewart194]

Thanks Pugsy! You've helped me out a lot over the last few years and I greatly appreciate it!