Everything is a UA (Help with ASV settings)

[Trash Hauler]

Hi All,

I'm having some technical difficulty and I'm looking for some advice (other than throwing the machine out the window) please. I'll try to make this a short story...

I was diagnosed with moderate OSA but also had lots of central events, about 40% of the apneas were recorded as central.  I did two in lab titration studies and both were essentially failures.  Never did get a good starting point for PAP therapy.  The short version is the doc prescribed an ASV machine and I have been trying to use it for a couple weeks now. Machine is a ResMed AirCurve 10 ASV. I use a Wellview/Viatom SleepU SpO2 sensor as well.

Doc wanted a cardiac workup before going all out with the machine so he restricted it to ASV EPAP 10 PS 0-5. Not working at all for me.  Can only manage a couple hours at most with this setting.  Cardiac testing was completed before Thanksgiving so hopefully the doc will be more forthcoming with the settings.  However, I wasn't willing to wait and I changed the settings to ASV Auto for the past two nights, actual settings are on the screenshots. I was able to use the machine for several hours last night but...

Since day one, all apneas are classified as UA. That kinda makes it difficult for the machine to properly adjust settings.
My SpO2 tanks periodically while I am using the machine (and sometimes when I'm not). For example, it dropped to 61% on the 21st and 68% last night.
I am constantly waking up while using the machine so sleep is very poor.

Obviously this isn't working. Recommendations? Why can't the machine determine the type of event? I'm guessing the SpO2 is related to the machine not knowing what to do.

Bob

[Sleeprider]

The ASV does not use the FOT apnea detection pulses to determine the type of apnea, but instead marks apnea as "unknown" or UA. In your case it is probably obstructive but your settings do not allow enough PS to resolve central apnea, so it's a little hard to know. Your EPAP is at 10 which should stop most OA events and you are using 0.0 to 5.0 PS. These are not appropriate settings to resolve central apnea events. Without more background on how you come to use ASV, I am left with two possibilities; you either have central apnea and need to modify your settings, or you have positional obstructive apnea (chin-tucking) which is causing airway obstruction in spite of the pressure.

I think the latter is the more likely scenario. I will link to our wiki article on positional apnea clusters. You will see the pattern of clustered apnea which closely resembles what we see in your chart and leads to the likely conclusion you need to avoid excess pillows or consider a soft cervical collar. http://www.apneaboard.com/wiki/index.php...onal_Apnea If the problem is central, you need at least 8-cm max PS, and may need up to 12 cm PS max.

[Trash Hauler]

Sleeprider,

Thanks for the input.  I will take a look at the link you sent.  I have never been on PAP therapy before. Due to the difficulties I had during the titrations, the doc went to ASV. See the notes below.

-------------------------------------------------------
Home sleep study with NOX T-3 device

BODY POSITION

- Time spent in supine position was 45.8 minutes (10.0% of MT)
- Time spent in non-supine position was 412.4 minutes (90.0% of MT)

RESPIRATORY PARAMETERS:

- AHI-4% was 21.3
- Supine AHI-4% was 44.6
- Non-Supine AHI-4% was 18.8
- Central Apnea Index was 4.2
- Total respiratory events included 79 hypopneas (4% rule), 51 obstructive
apneas, 1 mixed apneas, and 32 central apneas.
- Patient snored for 0.3 minutes during the study.
- Oxygen Desaturation Index 4% (ODI-4%) was 19.8
- Mean Oxygen Saturation was 91.7%
- Lowest Oxygen Saturation was 83.0%
- Saturations < 90%: 34.2 minutes (7.5% of MT)
- Saturations < 88%: 15.6 minutes (3.4% of MT)

-------------------------------------------------------------
First in-lab titration:

RESPIRATORY EVENTS: 

The patient was placed on pressure treatment starting with a pressure of 5 
cm, and was titrated to 10/5 cm.  During the titration, the AHI was 42.2 
(apnea index = 29.8, hypopnea index = 12.4) and RDI was 43.0.  There were 52 
respiratory events, with 27 central apnea, 3 mixed apnea, 6 obstructive 
apnea, 0 central hypopneas, 15 obstructive hypopneas, and 1 RERA. The total 
number of apneas and hypopneas was 51. The longest recorded event was 46.0 
seconds. 

The supine AHI was 74.3, and the supine RDI was 74.3. There were 10.5 minutes 
of supine sleep.
The non-supine AHI was 36.77, and the non-supine RDI was 37.74.

The patient's events were corrected while supine. 
No Cheyne-Stokes respirations were seen.

-------------------------------------------------------
Second Titration study:

RESPIRATORY EVENTS:

The patient was placed on pressure treatment starting with a pressure of 8/4
cm, and was titrated to ASV settings. During the titration, the AHI was 46.1
(apnea index = 34.3, hypopnea index = 11.8) and RDI was 46.4. There were 142
respiratory events, with 66 central apnea, 4 mixed apnea, 35 obstructive
apnea, 0 central hypopneas, 36 obstructive hypopneas, and 1 RERA. The total
number of apneas and hypopneas was 141. The longest recorded event was 62.5
seconds.
In REM the AHI was 96.0, and the RDI was 96.0.
The supine AHI was 43.8, and the supine RDI was 44.6. There were 75.3 minutes
of supine sleep.
The non-supine AHI was 47.69, and the non-supine RDI was 47.69.
The patient appears to do better at 14/10 cm of PAP, where there were 59
minutes of sleep with an AHI of 14 and an RDI of 15.
Mask leak was variable on this night.
No Cheyne-Stokes respirations were seen.

--------------------------------------------------
Here is the script from the doc:

Even though the patient had an adequate response to bilevel therapy 14/10 cm H2O,
his strong response to PAP with central apneas prompts me to want to have
option for control of his centrals should they occur. He had elevated heart
rate through the study and needs an ECHO before he would be able to use ASV
so I will alert his PCP that he needs cardiology workup before we can put him
on ASV. Therefore, I would like him to receive an ASVauto machine with
settings at EPAP min 10 EPAP max 10, PS min 4, PS max 4. Once he has
cardiology eval we can adjust settings if needed. This would essentially be
starting with bilevel and option for ASV.

Since they couldn't put the machine in pure BiPaP mode, the doc modified the script and went with ASV EPAP 10, PS 0-5.  That hasn't work for me.  I changed the machine to ASV Auto for two nights, one with EPAPmin 6.0, max 15, PSmin 3.0 max 19, basically let the machine have full control.  The machine kept throwing 25cm to me and waking me up so the next night I restricted it a bit.  EPAPmin 6.0, max 12 PSmin 4.0 max 10. 

I was able to use the machine for about 6 hours at those settings but still had a lot of events.  Also, when I took the mask off and tried to sleep, my SpO2 tanked, which it does not normally do and has not done after removing the mask while using straight ASV mode.

I know a good portion of this is simply getting used to using the machine but when my oxygen levels are dropping lower with the machine than without it and sleep is objectively worse, it is a challenge.

Doc wants me to continue as ASV EPAP 10 PS 0-5 for another couple weeks and wants a minimum of 4 hours per night with it.  Not having much luck with 4 hours per night at those settings. I would love to throw the machine out the window, but I have to get this figured out so I can return to work.

Here are screenshots from the two nights in ASV Auto mode. I took a mid-afternoon snooze on the 27th so one screenshot shows everything and one is zoomed in to exclude the nap.

Any other recommendations / advice is welcome.

Bob

[Sleeprider]

Thank you for providing this background and some charts. It appears your apnea is complex with both central and obstructive. Treatment with ASV has been recommneded with very unconventional settings, and the EPAP 10 PS 0-5 is clearly ineffective. Your experiments with EPAP 6-15 PS 4-15 is very close to default ASVauto recommendations. The night with EPAP 6-12 PS 4-10 looks like a good response to what your were seeing and to tame the pressures, but still resulted in high AHI.

I'd like to get a zoomed view of the events so we can see the flow rate, mask pressure and other graphs at a resolution that clearly shows the wave-form similar to this post by Jarlo. I'm looking for zooms that show 3-4 minutes of data, more like the first graph in that post, and use mask pressure instead of pressure. The clusters of events makes me think you may also be dealing with obstruction of your airway by twisting your neck or chin-tucking. You apparently sleep non-supine often, and I don't know if that is prone, left or right, but think about how your chin might tuck or your head turn to the side in ways that increase breathing resistance, and comment on that if you can.

[Trash Hauler]

Thanks again for the prompt reply.  Attached are 2 zooms from the 27th (asv auto) and one from the 21st (asv).  I couldn't link to the post you were referring to so these might not be exactly what you are looking for.  Please let me know.

I am an all position sleeper but have been unable to sleep prone with the mask.  The greatest likelihood is I am on my left side to keep the air from blowing on my wife but it is entirely possible that I'm on my right side too.

Positional apnea is possible also.  I'll be in town tomorrow and will swing by the DME to look at over priced cervical collars.  I have found my travel pillow to be more comfortable with the mask so I'm using it currently.  It is a memory foam pillow that I cut across the short axis.  Measures 16"x8"x3.5"  

Bob

[Sleeprider]

Read the Soft Cervical Collar wiki and look for a link to some reviews near the end of the article http://www.apneaboard.com/wiki/index.php...cal_Collar I don't think you should buy through a DME as most of their equipment is intended for cervical stability due to injury rather than stabilizing the airway. Read the wiki, and do a few tests like, relax into a chair and allow your chin to drop to your chest and note airway resistance. Also try turning your head like you might if you sleep prone, then drop your chin to your shoulder. The mechanisms of positional apnea are surprisingly simple and very common. We included a section on it in the Optimizing Therapy wiki http://www.apneaboard.com/wiki/index.php...onal_Apnea

The event in your chart at 01:03 looks mostly central. Hyperventilation at 01:01:45 diminishes to hypoventilation and transitions into apnea. The 10 cm PS breaths barely deflect your airway, and you either need higher pressure support to cause a breath, or your airway is obstructed. It appears to be open, and I think you may need up to 15 cm of PS max to move this. If we need to reduce pressure, I'd be more inclined to try lower EPAP. That is a significant event and SpO2 drops well into the hypoxic range, but recovery is very fast. The sequence at 06:01 is similarly severe with what appears to be an open airway and the is succeeding at 06:04 in causing some breaths. It just seems to need more PS to get the job done. The machine is raising EPAP through this segment without much effect. The third chart shows extremely disrupted deep flow-limited breaths at 8 BPM and the ASV has completely lost track of what to do. The mask pressure chart shows no PS. I have not seen that before.

[Trash Hauler]

I really appreciate you taking the time to help me out.  THANK YOU!!

The drastic SpO2 drops are very abnormal for me.  I have been using the sensor on and off for a while now (greater than an year).  I typically see many fluctuations between 99% and 90% with the occasional drop into the mid 80s.  I have never seen a drop into the low 70s, let alone low 60s prior to being on the ASV machine.  I think the machine is inducing the major drops.  Hopefully ASV Auto will fix it, just need to get it dialed in.

For tonight, I will try EPAPmin 6, max 12 with PS 4-15 unless you have a different recommendation.

Last night I played around with ASV mode and tried EPAP=10 PS 3-10.  Had similar results to the other ASV sessions.  Didn't last long and didn't help much.

Thank you again


Bob

[Trash Hauler]

Looking at the screenshot from above where you noted the deep flow-limited breaths, I think the timing on that screenshot wasn't good.  I bet I was awake from the SpO2 sensor going crazy and I was intentionally taking deep breathes to get the oxygen level up and stop the sensor from vibrating.  As for why no PS, no idea.

[Sleeprider]

I think if we can sort out the cause for your obstructive apnea component, the centrals should follow. My hope is that we can address any positional issues to minimize that, then limit EPAP range lower while allowing enough PS to make you breathe when the airway is open and you are not spontaneously breathing.

I'm sure you have seen this, but it might be interesting to use the default ASVauto settings just to see what you get.

[Trash Hauler]

Appreciate.  I do have that chart, I'll give the default settings a shot and see how it goes.  Hoping to keep the max IPAP down to around 20cm since 25 was waking me but we shall see.

Bob