New ASV user + Sleepyhead data

[lidocaineus]

So after three full sleep studies I've been diagnosed with complex apnea that's untreatable by BiPAPs but ASV fortunately clears up; my AHI was in the 80-100 range, which is reduced to < 1 with an ASV, so it seems like it's been pretty effective.

I've tracked my data with Sleepyhead, and being a heavy data analysis type person, I've found it incredibly interesting. I've got a very basic understanding of the more important stats, but a lot of the documentation and stuff I've read about analysis focuses on C/BiPAP type patterns; since ASV adjustments happen far more on the fly, it seems to thrown things for a loop.

For example, it seems the ASV only identifies hypoapneas and unidentified apneas. I'd like to ID if those are OSAs or CAs. I can see the pressure spiking during those events, but I'm not sure how to interpret the flow rate data.

Here's a hypopapnea, which makes sense, as the flow rate just before seems markedly erratic (I would've posted the images directly but I'm unable to post clickable links apparently).

   

And here's an unidentified apnea, which shows a very flat flow rate. Is there a way to determine if that's an OA or CA event?

   

Finally, is there a way to tell how "hard" the machine is working at preventing apneas? I'm assuming the pressure spikes throughout the night would be a sign that it's adjusting for things pretty often, or is this just normal? I know ASVs are designed to assist with a certain amount of pressure in terms of inspiration, but I'm not sure where to identify what's a normal assist, and when it's starting to detect irregularities and starts hiking up the pressure.

Here's a snippet of just under an hour where the pressure spikes a bunch up to 21 cmH20 and also levels off later.

   

Can anyone help me take a stab at interpreting the data?

[PaytonA]

It is my understanding that ASVs do not "assist" unless they sense that you are not initiating a breath in a normal time period. The spikes are driven by the ASV using the Pressure Support. OAs are controlled by the EPAP pressure. My feeling is that any apnea that occurs within the normal breathing time is considered to be probably not a CA and if the ASV is an auto will raise the EPAP. If you do not initiate a breath within the *normal* breath cycle then the ASV gives you a kick in the Pressure Support (pressure spike) to attempt to get you to initiate a breath.

I am not an ASV user and what I have said above is my impression from what I have read on this board by ASV users.

Best Regards,

PaytonA

[richb]

Hi lidocaineus. Welcome to the Apnea Board. Yes all of those spikes in pressure is your ASV machine trying to get you to breathe. It seems to be doing pretty well. Occasionally things get messed up and Hypopneas and Unidentified Apneas sneak through. The spikes are what would be Centrals without the machine. Hypopneas are difficult to identify (Obstructive vs Central) and the machine can't quite figure what is happening during those Unidentified events. You have an AHI under 1 which is better than most people using XPAP machines. Those rare events that you are asking about could be caused by you partially waking up or even a change in sleeping position. I am on an ASV machine and get them as well. Keep reading threads on this Board regarding ASV, Hypopneas, Unidentified Apneas, and anything else that strikes your fancy. Feel free to ask questions as you get a better hold on your therapy.

Rich

[DeepBreathing]

G'day lidocaineus, welcome to Apnea Board.

The Resmed ASV machines don't make any distinction between obstructive or central apneas - they just get on and treat them, with lightning fast reactions. According to Resmed's literature, their algorithm completely suppresses central apneas so any events which are registered are obstructive in nature. I think that presupposes that the pressure settings are appropriate, which is not always a given.

I find the mask pressure graph is more useful than the regular pressure, as it shows both EPAP and IPAP on a breath-by-breath basis. This allows you to easily see a normal level of assistance and when the machine starts working hard. (The normal level is when everything is going smoothly and pressure assistance PS will be at the minimum setting).

It would also be good to see the summary panel from SleepyHead, which shows your basic machine settings and your min, max and median outputs. I have to say your pressure graph looks a bit weird, especially in your first image, so it would be good to know what your settings are. Can you let us know your EPAP_min, EPAP_max, PS_min and PS_max? Given your excellent AHI, the apnea is well under control, but it might be possible to moderate the pressure swings and give you a more comfortable sleep.

[lidocaineus]

Had to add these as non-clicky links because I'm running into the 200kb attachment limit and it's not letting me post links yet as new user.

I took a closer look and you're right; the mask pressure graph is better at analyzing per-breath results. Seems the regular pressure graph is more about how it's ramping pressure up and down in general since it separates out the E/IPAP stats. My EPAP is at 5 and is apparently that for min/median/max (could just be a quirk of how the epap stat is registered) and IPAP is set to max at 21, and the actual stats are at 5 for the min, 10.14 for median and my 95% is 16.26, though I do hit a max 21. PS min == 3 and max == 16, though I'm not exactly clear on what the PS min/max is. Here's the stats panel:

staff.bluemaggottowel.com/hose/images/v6.png

staff.bluemaggottowel.com/hose/images/v4.png

Like I said, it definitely makes interpreting easier with the mask pressure. Looks like here it was clearly a hypopnea where I didn't make any significant inspiration for > 10 seconds, even when the machine ramped up the pressure (around 1:24:35) and I didn't take a breath until it ramped it all the way up to 21. There was a similar event earlier at 1:23:35 and 1:24:20 but was under 10 seconds, so it didn't qualify.

Also here's a steady state, and you can see just about how much the machine is attempting to compensate per breath. Pretty cool; looks like I'm giving the machine a decent workout all night.

staff.bluemaggottowel.com/hose/images/v5.png

The data is still really interesting, but it sort of bugs me that we don't know exactly how it's generating it; the analyst part of me is nagging at the fact that we just have to take the values as truth without knowing the actual process. Oh well, guess we'll never really get a good look at that part unless by some miracle they open source it up (highly doubtful as it looks like it's encumbered with a number of proprietary stuff).

In general, I'm kind of impressed at how quickly it adjusts on the fly. There are some parts where you can literally see my flow rate decreasing per breath and the machine slowly ramping up per breath to adjust. I'm surprised they don't Rx ASVs all the time versus regular xPAPs as they seem way "smarter", though I guess this is a cost thing and xPAPs are able to resolve other people's issues without going all the way to an ASV.

[trish6hundred]

Hi lidocaineus,
WELCOME! to the forum.!
It sounds like you are off to a good start with your new ASV machine
Good luck to you as you continue your CPAP therapy, hang in there for more responses to your post.

[DeepBreathing]

Your machine is set to "ASV" mode in which the EPAP remains at a constant setting of 5. I prefer "ASV Auto" where you can set a range for the EPAP and the machine will operate within that range. It will help overcome any residual obstructive apneas and (in my experience) it tends to smooth out the fluctuations a bit as it doesn't need to run such a high PS.

Just by way of explanation (and forgive me if I'm telling you something you already know)... EPAP is expiratory PAP(positive airway pressure), or the base setting when you're breathing out. This is the pressure which splints your airway open and prevents obstructive apneas. PS is pressure support - the additional pressure which the machine applies to help you inhale. If you're doing well then PS will stay around the minimum. If it detects a reduction in airflow, then the machine will increase PS accordingly. IPAP is inspiratory PAP - the pressure when you're inhaling. By simple arithmetic, IPAP = EPAP + PS. So if your EPAP is stuck on 5 and PS_max is 16, then your IPAP will go up to 21, which is what you saw on the chart.

Anyhow, your numbers look great. The main thing now is to ensure you're comfortable and getting a long and refreshing sleep.

[lidocaineus]

Thanks - that cleared up my confusion with the numbers. Now it makes more sense. With that info, it looks like I can compare the flow rate of individual breaths via the mask pressure, and the overall pressure allows you to see how the device is trending over periods of time.

My past two night I've had zero events (outside of 2, which were clearly start / end junk), so if things don't change for the worse on that side of things, I'm going to work on general comfort issues like sleeping on my back (was always a front sleeper) or on my side (seems easy to cause leaks when the mask comes into contact with the pillow).