Why would the majority of my AHI be made up of clear airway events?

First time poster to these forums so thanks for the help in advance. I routinely experienced bad snoring throughout my life and perpetual tiredness(lack of productive sleep). I was diagnosed with moderate sleep apnea several months back after doing a sleep study(AHI measured at 15). I had a follow-up sleep study that determined I needed BiPap at 12:4. They said I was intolerant to nasal CPAP. So I got my machine about a month after that. Aircurve BiPaP machine with an Eson Nasal Mask.

Anyways, I regularly check MyAir(ResMed's data app) and I generally notice varying AHI's(some nights high and some low). The last couple of nights my AHI have been well over 10 so I decided to download Sleepyhead to look more indepth at my data(MyAir only gives me a general AHI). I noticed that the bulk of most of my AHI's were made up of Clear Airway events and not obstructive events. So i'm confused as to what is going on.

I've adjusted to the therapy fairly well, but I still feel just as tired as before. Most nights I tend to get around 6 hours of therapy in before I wake up. Some nights I lay back down with the mask on, but sometimes I take it off for about 1-2 hours more of sleep. Several times i've woken up having removed my mask throughout the night(hasn't happened recently though). My wife has said that, on occasion, she hears air escaping my mouth and I do wake up bloated often(having swallowed some air). The doctor gave me the option for a chin strap or full face mask. I went with the strap because it was cheaper, and my wife has said that she doesn't notice the escaping air as much now.

I'm just looking for some advice in this situation. My doctor is retiring in a couple months, so I won't be able to go back to him for adjustment. I am going to have to find a new doctor. I have posted the last couple nights of data I have from SleepyHead. Thanks again for any help provided.


https://imgur.com/ABclcqI
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Do you have any history of lung problems at all? Like COPD or some sort of restrictive lung disease?

If not...I question why the big difference between inhale at 12 cm and exhale at 4 cm...that means 8 cm PS and that's a huge PS number unless there is some sort of lung problem needing to be addressed.

If it were me I would want to cut that PS in half and maybe try PS of 4 instead of 8.
So maybe 6 EPAP and 10 IPAP.

When the difference between inhale and exhale is too high it can cause central apneas because too much carbon dioxide gets blown off and the blood levels don't get high enough for the brain to send the breathe signals.

Alucard84 wrote: ↑

Sun May 20, 2018 11:53 am

Why would the majority of my AHI be made up of clear airway events?

Most likely, because of this:

Alucard84 wrote: ↑

Sun May 20, 2018 11:53 am

BiPap at 12:4.

a PS of 8 is a LOT, and a EPAP of 4 doesn't provide a lot of oxygenation.

You're likely being hyperventilated all night long, and your body just doesn't feel the need to breath.

I second what Pugsy said.

I do not have any underlying lung issues. I did not see the doctor in between my second sleep study and getting the machine, so nobody really explained to me what the settings meant. They just gave me the same machine and showed me how to use it. I followed up with the doctor about a month after using the machine. He looked over my report and told me to use the machine more and work on my obesity. Suggested a chin strap or full face mask for the mouth opening. The therapist that gave me the machine said I could not alter the pressure settings myself. The prescription would have to be changed by the Doctor. I'm not sure I want to go back to him though. He was seeing all the numbers I am seeing right now and his answer was to use it work and lose weight. I think I need to wait for his replacement or go out of town for another Doctor.

You can change the pressure settings yourself if you want to and are comfortable doing it.
It's not difficult at all.

Go here and request the clinical/provider manual for your model ResMed machine and you can easily find the secret handshake for getting into the clinical setup menu to make a change yourself.
https://www.apneaboard.com/adjust-cpap- ... tup-manual

Alright. I will play around with it. Thanks for the advice.

If you don't already have a copy of your prescription and your sleep study and titration (2nd study), I would get them. It would be interesting to see if you had centrals on the study and how they came to the settings you were given.
I think you will have a notable difference with the decreased pressure setting. For most people with out complicating lung conditions the 4PS is used.

OkyDoky wrote: ↑

Sun May 20, 2018 4:40 pm

If you don't already have a copy of your prescription and your sleep study and titration (2nd study), I would get them. It would be interesting to see if you had centrals on the study and how they came to the settings you were given.
I think you will have a notable difference with the decreased pressure setting. For most people with out complicating lung conditions the 4PS is used.

*IF* the OP has *severe* Obesity Hypoventilation Syndrome, then a higher PS can make it easier to inhale... when on their back... which they shouldn't be... etc etc...

I can't think of another good reason for a PS of 8 though, absent other lung issues... and if they had them, they shouldn't have been shoved out the door with that machine and ignored.

These are the only reports I have seen. This is the first sleep study:

"INDICATIONS: The patient is a 33-year-old white male referred to sleep lab for
investigation of obstructive sleep apnea. His history and physical features
suggest obstructive sleep apnea in the setting of obesity (height 6 feet 1
inch, weight 275, BMI 36).

The patient was studied on the evening of the 11/01/2017. He slept 345 minutes
out of total time in bed of 504 minutes to give him sleep efficiency of 68%.
Sleep architecture 11% stage I, 60% stage II, 5% stage III, and 25% REM sleep.
There were no nocturnal leg movements. His apnea-hypopnea index using 3%
desaturation and/or arousal was 15.3. His apnea-hypopnea index using 4%
desaturation was 4.5. His oxygen saturation on occasion dropped to as low as
84%.

IMPRESSION:
1. Moderate obstructive sleep apnea with moderate hypoxemia.
2. Obesity.

RECOMMENDATIONS:
1. Return to sleep lab for nasal CPAP titration study.
2. Effort at weight loss."

This is the second:
"INDICATIONS: The patient is a 33-year-old male previously found to have
obstructive sleep apnea in the setting of obesity (height 6 feet 1 inch, weight
275, BMI 36).

The patient returned to the sleep lab on the evening of 02/20/2018 to undergo
CPAP/BiPAP titration. He ultimately was found to have an optimal pressure
setting using BiPAP at 12/4 (he was intolerant to nasal CPAP) at this BiPAP
level of 12/4, a complete resolution of all snoring and apnea, his oxygen
saturation remained normal. He slept 236 minutes out of 394 minutes to give
him sleep efficiency of 60%. Sleep architecture reveals 7% stage I, 86% stage
II and 7% REM sleep. There were no nocturnal leg movements noted.

IMPRESSION:
1. Obstructive sleep apnea -- corrected with nasal BiPAP, 12/4.
2. Obesity.

RECOMMENDATIONS:
1. Night use of nasal BiPAP -- 12.4.
2. Analysis of smart card data chip in 8 to 10 weeks to assure compliance and
meet all regulatory requirements.
3. Effort at weight loss."

palerider wrote: ↑

Sun May 20, 2018 5:27 pm

*IF* the OP has *severe* Obesity Hypoventilation Syndrome, then a higher PS can make it easier to inhale... when on their back... which they shouldn't be... etc etc...

I can't think of another good reason for a PS of 8 though, absent other lung issues... and if they had them, they shouldn't have been shoved out the door with that machine and ignored.

Right, this is a possibility and greater PS would augment tidal volume, that's why I brought up the sleep study. If that was the case, monitoring seems to be lacking.

What I was wondering about was your O2 levels at different settings on the titration. Some full reports have those. The sleep study does show that centrals weren't a concern initally and developed with treatment. Try the new settings and let us know how they work.

So I went ahead and slept another night at the 12.4 pressure just to see what would happen. Same results. Posted the graph down below. I also updated my Doctors Office to the problem and they suggested a full face mask and if that didn't work, pressure adjustment. So I'm going to give that full face mask a week at the 12.4 and if that doesn't work, im going to tell the Dr that I would like to try different pressures. I figured I would go along with them for now just to get the free mask. I did figure out how to adjust the pressure last night. It was fairly simple.



https://imgur.com/a/wzfEe22

Alucard84 wrote: ↑

Mon May 21, 2018 3:59 pm

So I went ahead and slept another night at the 12.4 pressure just to see what would happen. Same results. Posted the graph down below. I also updated my Doctors Office to the problem and they suggested a full face mask and if that didn't work, pressure adjustment. So I'm going to give that full face mask a week at the 12.4 and if that doesn't work, im going to tell the Dr that I would like to try different pressures. I figured I would go along with them for now just to get the free mask. I did figure out how to adjust the pressure last night. It was fairly simple.



https://imgur.com/a/wzfEe22

A different mask isn't going to make any difference.

You are right. The full face mask was a bust. I played with it last night and it leaked like a sieve no matter how I adjusted it. I ended up going back with the nasal mask and I adjusted the setting to what was suggested. AHI was 2.64. Was a little more difficult to fall to sleep with this higher exhale, but I will get used to it. I did wake up in the middle of the night with the machine off. Don't know if I accidentally hit it or subconsciously turned it off in the middle of the night. Is this possible with the pressure change maybe? Anyways, do I need to make any more adjustment or just run with this for awhile?

https://imgur.com/a/ErIr1df

Your results for last night look much better. The CA's are at the beginning of your sleep and you can probably disregard them. I would continue this setting for a few more days and check results. I wouldn't worry about about this machine turn off but if it continues you might move the machine where you can't reach it easily.