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Inhalation/Exhalation Problem
#1
This is my first post.
I have been on Bi-pap for 8 months now. I had an AHI of 34 in my sleep study. I tried 3 different machines now and have finally found the one that works for me. I have the ResMed AirCurve 10 VAUTO which I have used for 3 months now. My apneas have come down to a normal level averaging 2.4 for the last 3 months and 1.9 for the last 1 month. I am quite happy with that. Most of my apneas are Centrals, however I had no Centrals in my sleep study at the Sleep Lab. I'm assuming the machine is causing the centrals but since my AHI is normal I am not too concerned. My sleep doctor said it was hyperventilation.

My problem is that on many nights, usually after 4:00am I feel that I am being forced to breathe faster. The inhalation starts before I am done exhaling. If I stop the machine and restart it of course my breathing goes back to normal again. But then when the pressure builds up again it will repeat the fast breathing again. My therapist is making adjustments every 2 t 3 weeks to try to correct this but no success yet. My Ti max is set at 2.0, Ti min 0.3. The trigger is set to medium and the cycle set to low.

If anyone else has had a similar problem I would love to hear how you rectified it.
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#2
Central or clear airway apneas as measured by your machine can be caused by excessive pressure support. It would help to know what your complete settings are. Your profile shows 8/15 which might imply EPAP of 8 and IPAP of 15 or PS of 7.0. Your machine is capable of treatment at a range of pressures. Can you clarify what pressure support is used on your machine?

I also use auto bilevel, and you can see my settings in my profile to the left. You will have something similar, except your Pressure Support will be a fixed value on Resmed. I also have minor short duration CA events but no OA. I don't find them disruptive to my sleep as compared to the increased obstructive events with lower pressure support.
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#3
I believe that machine can also be run in one of three modes: straight CPAP, "S"* mode bilevel, and bilevel auto.
So, in the setup menu, for mode, it would say: CPAP, S, or Auto. I think it would be good to check the mode setting.
For CPAP mode, one pressure is specified, for S mode: two pressures (IPAP and EPAP), and for Auto: 3 pressures (IPAPmax, EPAPmin and PS.)**


*(S = Spontaneous trigger to/from IPAP/EPAP)
** Resmed handles Bilevel a tad differently that Phillips-Respironics Bilevel.
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#4
(12-02-2015, 07:31 PM)Sleeprider Wrote: Central or clear airway apneas as measured by your machine can be caused by excessive pressure support. It would help to know what your complete settings are. Your profile shows 8/15 which might imply EPAP of 8 and IPAP of 15 or PS of 7.0. Your machine is capable of treatment at a range of pressures. Can you clarify what pressure support is used on your machine?

I also use auto bilevel, and you can see my settings in my profile to the left. You will have something similar, except your Pressure Support will be a fixed value on Resmed. I also have minor short duration CA events but no OA. I don't find them disruptive to my sleep as compared to the increased obstructive events with lower pressure support.

Yes, the 8 is my EPAP and the 15 is my IPAP. My pressure support is 3. I hardly ever have any obstructive apneas. I can go 10 days without one. I have anywhere from 1 to 3 hypopneas and the rest are centrals.
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#5
(12-02-2015, 07:54 PM)justMongo Wrote: I believe that machine can also be run in one of three modes: straight CPAP, "S"* mode bilevel, and bilevel auto.
So, in the setup menu, for mode, it would say: CPAP, S, or Auto. I think it would be good to check the mode setting.
For CPAP mode, one pressure is specified, for S mode: two pressures (IPAP and EPAP), and for Auto: 3 pressures (IPAPmax, EPAPmin and PS.)**


*(S = Spontaneous trigger to/from IPAP/EPAP)
** Resmed handles Bilevel a tad differently that Phillips-Respironics Bilevel.

My machine runs in auto mode. EPAP is 8. IPAP is 15 and pressure support is 3.
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#6
Good, the missing PS number. Your pressure support is low, relative to most bilevel users. Your pressure is staring out at 11.0/8.0 (IPAP/EPAP), and may range as high as 15.0/12.0. The fact your therapy has reduced obstructive apnea to a very low incidence shows that aspect is successful. CA events, are well within tolerable limits considering your total AHI is currently less than 2.0.

With your AHI essentially resolved, your immediate problem is a sense of the machine not timing your natural respiration well. It sounds like you are working with your RT, and she is making adjustments to the default Ti settings. In my opinion, it's probably not necessary to change the defaults, and this is a common problem in adapting to bilevel, or even APAP with EPR. You control the respiration rate and timing not the machine. When it seems to be off-sync, you should be able to consciously inhale and exhale with enough force to re-sync the machine. The sense of the machine taking over is only because you are pausing your breathing and the machine senses this as the completion of the inhale or exhale (probably exhale). When you do that, the machine senses the change the pressure and so it increases pressure for the inhalation. You feel that as the machine taking over, but you can stop it, by exhaling against the pressure. It's also likely that when you pause breathing at the bottom of the exhale, the machine senses this as a CA. All of this is normal and will eventually pass.
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#7
Daniel,

During the time that you are having this problem, expand your flow rate graph and look at the downhill side of the inhalation portions of your curve. Look to see if there is a little hitch in this section where it stops descending or starts a small ascent for a very short period of time. Let me know what you see.

Best Regards,

PaytonA
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#8
(12-03-2015, 10:50 AM)Sleeprider Wrote: Good, the missing PS number. Your pressure support is low, relative to most bilevel users. Your pressure is staring out at 11.0/8.0 (IPAP/EPAP), and may range as high as 15.0/12.0. The fact your therapy has reduced obstructive apnea to a very low incidence shows that aspect is successful. CA events, are well within tolerable limits considering your total AHI is currently less than 2.0.

With your AHI essentially resolved, your immediate problem is a sense of the machine not timing your natural respiration well. It sounds like you are working with your RT, and she is making adjustments to the default Ti settings. In my opinion, it's probably not necessary to change the defaults, and this is a common problem in adapting to bilevel, or even APAP with EPR. You control the respiration rate and timing not the machine. When it seems to be off-sync, you should be able to consciously inhale and exhale with enough force to re-sync the machine. The sense of the machine taking over is only because you are pausing your breathing and the machine senses this as the completion of the inhale or exhale (probably exhale). When you do that, the machine senses the change the pressure and so it increases pressure for the inhalation. You feel that as the machine taking over, but you can stop it, by exhaling against the pressure. It's also likely that when you pause breathing at the bottom of the exhale, the machine senses this as a CA. All of this is normal and will eventually pass.

Thanks ever so much for your tips. I will try and control my breathing as you suggested and not let the machine control it. If I can get that under control then my therapy will be pretty well perfect.

Daniel
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#9
(12-03-2015, 11:26 AM)PaytonA Wrote: Daniel,

During the time that you are having this problem, expand your flow rate graph and look at the downhill side of the inhalation portions of your curve. Look to see if there is a little hitch in this section where it stops descending or starts a small ascent for a very short period of time. Let me know what you see.

Best Regards,

PaytonA

The graph shows that after the curve hits bottom it goes up about half way and then goes sideways a bit and then continues to go upwards.

Daniel
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#10
I have the same machine, with a similar path to get there. I am pretty sure that T1 is max inhale time and has nothing to do with exhaling. The machine for me kept cutting off my inhale which is very frustrating. It's like with each inhale right near the end someone puts their hand over your nose. the change from exhale to inhale is triggered by your breathing, for the machine to try to speed up your breathing means it is being triggered too soon. Perhaps change the trigger sensitivity.

For my inhale thing I had to set T1 to 3. Oh and T2 is the minimum inhale and will try and keep you inhaling for at least that long, if the machine is getting triggered at the end of your exhale into thinking you are inhaling maybe the T2 number is getting the machine to blow more air into you.

Try adjusting the trigger level and then maybe the T2 number a little longer and see if it gets better.
If you think that in your sleepy state you might be mixing up end of inhale with length of exhale, try adjusting T1 longer.
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