AHI stuck around 10

[PercyA]

Hello all,


I was diagnosed with Obstructive Sleep Apnea about 2 years ago now, at the time I had an AHI of around 75. I got my CPAP machine and started using it nightly, but I noticed my AHI never dropped below 15 (according to my ResMed AirSense 10 machine readout that is).

I thought some of my issues may be due to my seemingly enlarged tonsils, so I went to an ENT, who strongly recommended against me getting my tonsils taken out and instead suggested I get my deviated septum fixed. I went ahead with the deviated septum surgery, which I had about a year ago now.

After that nose surgery I had another sleep study done, this time I had around 55 events per hour. I have information from this report below (I tried to attach a picture of it, but it's too large). 


I now see my AHI hover around 10 or 11 most nights, and I'd love to get that down lower, but I'm not sure how to go about that at this point.
I've talked to my primary care doctor about this a few times, wondering if there was a machine configuration change I could change that may help, but they seem to not know much about the machines themselves.

I just started using OSCAR to read the data from my machine, but I'm a little unsure of what to change after reading the output.

My machine was originally configured to be in APAP mode and to have a minimum pressure of 2 with a maximum pressure of 20.

Two nights ago now I bumped up my minimum pressure to 7, but I haven't seen any change.

Does anyone have any recommendations on how to go about reading the OSCAR output in order to figure out the correct pressure and CPAP vs APAP mode that I should be using?

Happy to include more device settings, statistics, and other information if that's helpful.

More information about my setup:
* ResMed AirSense 10 machine
* I'm using a full face mask

Current Device Settings:
Mode APAP
Pressure Min 7.00 cmH2O
Pressure Max20.00 cmH2O
Antibacterial FilterNo
Climate Control Auto
EPR Full Time
EPR Level 3 cmH2O
Essentials Plus
Humidifier Status On
Humidity Level 4
Mask Full Face 
Ramp Auto
Ramp Pressure 4 cmH2O
Response Soft
Smart Start On
Temperature 27 ºC
Temperature Enable On

Report from after septum surgery sleep test:
* AHI = 54.8
* RI = 57.9
* Apnea Index = 53
  * UAI = 0
  * OAI = 43
  * CAI = 8
  * MAI = 2
* Average breaths per minute = 9.72
* Breaths = 2683
* Apenas: 
  * Unclassified = 0(0%)
  * Obstructive Apneas 199 (81%)
  * Central Apneas = 39 (16%)
  * Mixed Apneas = 7 (3%)
* Hyponeas = 7
* Snoring Events =  218

[Sleeprider]

Welcome to Apnea Board. I think we an help you with this. Your Autoset is set to 7-20 pressure with EPR 3, which means you start at 7/4 pressure (inhale/exhale), which is quite low. Your median pressure is nearly 10.0, so your new minimum pressure needs to move to 11.0 (I'll explain) and that will result in 11/8 pressure. Ramp is on Auto, but it goes on nearly 45 minutes. Find some way to increase your Ramp pressure or turn it off. Your events are mainly obstructive, and I think event the events flagged central are also obstructive. When we look at your chart, the thing that stands out is how events are clustered together, and the fact your therapy starts at 04:00. Are you a shift worker, like to party, or is your clock set wrong? Anyway events are clustered together which tells us your airway becomes intermittently obstructed, and it has no relationship to pressure.

During ramp your machine does nothing, and does not detect events or flow limits, but it's really obvious from all the flow rate spikes during ramp that it's NOT working. You need higher pressure or turn off ramp. All of those spikes represent recovery from uncontrolled apnea. After ramp, your pressure jumps well above your minimum set pressure to over 10 cm, and slowly declines until 05:37 when you have an apnea and the pressure rebounds. Then at 06:00 you have a significant cluster of obstruction which drives pressure to 12 cm. Pressure again declines until 06:50 where your pressure again rebounds from 9.0 to 13.0...rinse and repeat. This happens all night. Lesson should be learned here that apnea happens under 11/8 pressure, and it is clustered. Even when you don't have apnea, we see flow limits and hypopnea that are derived from sudden increase in obstruction. This clustering of apnea and poor correlation to pressure is a common pattern of what we call "positional apnea" or chin-tucking https://www.apneaboard.com/wiki/index.ph...onal_Apnea

We can correct this with changes in your sleep positioning including use of pillows, inclined sleeping, chin-tucking, and we often recommend a soft cervical collar to stabilizer the airway https://www.apneaboard.com/wiki/index.ph...cal_Collar That's what I see, and I'll let you digest this and see if any of it makes sense to you.

[PercyA]

Thank you for your response!

This is all great info to have!

> Your median pressure is nearly 10.0, so your new minimum pressure needs to move to 11.0 (I'll explain) and that will result in 11/8 pressure. Ramp is on Auto, but it goes on nearly 45 minutes. Find some way to increase your Ramp pressure or turn it off.

I went ahead and set my minimum pressure to 11, keeping my maximum at 20. I also had no idea that my ramp took this long, I just changed it to start at 8 and only ramp for 15 minutes. I'm gonna try that out tonight and if it isn't too uncomfortable, I may just remove the ramp all together.

> When we look at your chart, the thing that stands out is how events are clustered together, and the fact your therapy starts at 04:00. Are you a shift worker, like to party, or is your clock set wrong? Anyway events are clustered together which tells us your airway becomes intermittently obstructed, and it has no relationship to pressure.

Ah I think my time zone my be set incorrectly in OSCAR. I went to bed just before midnight last night and woke up around 6:30 this morning, so I think the time is just shifted.

> Lesson should be learned here that apnea happens under 11/8 pressure, and it is clustered.
Your analysis here is amazing! Thank you for taking the time to make it. Would you mind elaborating on the "clustered" part here. I also noticed they tend to happen all together, but I'm not sure what that indicates.

Is it just the fact that I have a cluster of apneas around the time my pressure drops under that 11/8 you mentioned or do you think there's something else going on there?

> Even when you don't have apnea, we see flow limits and hypopnea that are derived from sudden increase in obstruction. This clustering of apnea and poor correlation to pressure is a common pattern of what we call "positional apnea" or chin-tucking

I had no idea this was a thing! Funny enough, I often purposefully tuck my chin when laying down. I do this just because my partner has complained that the air venting from my mask is bothersome, and tucking my neck changes where that venting happens. I'm going to look into those collars you mentioned.

Right now my plan is to:
* Change min pressure to 11
* Temporarily change ramp to start at 8 and only run for 15 mins, if this is tolerable I may turn off ramp completely
* Look into buying a neck collar

I'll try to remember to update this thread with any interesting outcomes. Thanks again!

[Sleeprider]

Ramp also has an auto setting to detect "sleep breathing". It works in place of setting a specific time and works pretty good. Your main problem is your ramp pressure was set too low to be even comfortable. I think you might be able to use a lower pressure and achieve efficacy IF you resolve positional issues. My analysis was based on conditions of your last sleep. Remember the EPR subtracts from minimum set pressure, and most obstructive apnea will occur out of exhale, so 4.0 is not going to cut it. With pressure at 10, exhale is 7 and at 11 it is 8.0. With OA, that is what we're tracking.