Help Understanding Sleepyhead Graph?

I'm trying to interpret a portion of my results from last night. The first half hour or so of my sleep was fine, with no events at all and minimal leaks. Then around 1:02 a.m. my S9 started to increase pressure, apparently without any events to trigger it. Over the period from 1:02 to 1:12, my pressure increased from 10 to 14 cmH2O. Finally at 1:12, with my pressure at maximum, I had my first apnea of the night.

So my question is this: why did my S9 increase my pressure without any event to trigger it? Shouldn't pressure increases follow events, not precede them?



Note: this is not the first time I have noticed a pattern like this. This is just an example.

Actually the S9 responds mainly to snores and flow limitations and the reason you don't see any apnea events being flagged is that they have been prevented. It also won't respond to a single apnea event that slips through the defenses..you need more than one for the machine to want to do anything and usually if you have more than one close together you will also have at least some flow limitations for it to respond to.

The S9 doesn't really try to fix the apnea event when it is actually happening...it works on preventing them in the first place and it uses snores and flow limitations to help it get the best idea what it needs to do because those are the first warning signs that the airway is trying to collapse.

Those clusters of events starting about an hour after you mask up. Might be REM stage sleep or might be supine sleeping or both which is common to see more airway tissue collapse and/or the need for more pressure.
The higher pressure needs that are fairly constant later in the night....that again might be related to REM stage sleep because we typically have more frequent REM stages that last longer as the night progresses with the greatest amount of REM happening in the wee hours of the morning. Might also be related to sleeping on your back. Sometimes we sleep on our back and don't know it.

A little more minimum pressure would likely prevent those clusters of OAs...either that or reduce EPR.
If the minimum pressure is more optimally set then the airway is held open better in the first place and has a greater chance of not collapsing as much which in the long run means the maximum pressure might not be needed.
Prevention is easier than fixing after the fact.
Reducing EPR effectively increases the minimum pressure...example if you are using EPR of 2 that means the pressure during exhale is reduced by 2 cm...so if 10 inhale that makes 8 exhale. If you reduce EPR to 1 then the exhale pressure is just reduced to 9 and that might help hold the airway open better.
Of course some people might find that EPR of 1 doesn't feel so great and if that happens then they can just increase the starting 10 cm pressure to 11 and keep EPR at 2 and the exhale pressure will be 9. That 1 cm difference during exhale might be enough to better prevent the airway from collapsing as much and if it does want to collapse the 9 cm starting point gives the machine a better head start to get to where it needs to keep the airway open.
End result is the maximum might not even be needed or if it is needed it is only briefly..OA clusters are broken up and usually the 95% pressure number reduces.

The minimum pressure setting on APAP machines is the most critical setting.
You likely need a little more minimum pressure to prevent those clustering of obstructive events (assuming the report you show here is a typical report)..probably not much...and the increased pressure needs might be from REM sleep or supine sleeping or both.

Ah, thanks for the info. So the fact that my flow decreases around 1:00 a.m. explains why the pressure increases.
I am in fact sleeping on my back; I cannot sleep in any other position due to shoulder issues. As for REM, I have noticed a pattern over the week of data I've got that I tend to have clusters of of centrals later in my sleep period which it seems likely are correlated with REM sleep. I don't know whether the clusters of obstructives in the first half of the night are similarly correlated.

I suspect that an increase in the minimum pressure is needed, as you suggest, but I have a question: will changing my settings without a prescription change affect my compliance? I don't yet own this machine, and my compliance is monitored via cellular modem.

The first stage of REM normally begins around 90 minutes after sleep onset...give or take 30 minutes..that first OA cluster very well could be REM related.

The DME is monitoring hours of use mainly for compliance. They don't often really look at the AHI or pressures (if they even get them with remote monitoring via the modem). The DME needs to be able to prove to the insurance company that you are using the machine at a minimum ...the required number of hours. Your insurance company could care less about what pressure you use or don't use. They never see anything but a statement of hours used. Your insurance company doesn't do any evaluation as to therapy itself beyond hours of use.
I don't know how upset your DME or doctor might be if you increased the minimum on your own just a little. Some won't even notice and some might notice and slap your hands for doing it and some will see the logic and reasoning behind it and be okay with it. After all you are using variable pressures anyway. We as patients aren't supposed to be smart enough to figure this stuff out but it isn't rocket science. A DME person can't change the pressure setting without an okay from the doctor similar to a pharmacist not being able to change a prescription med dosage RX without okay from the doctor...but if you get the pills home and don't take them exactly as directed on the label they don't come and take the pills away. They won't take your machine away either. At the most you might get a slap on the hands and be told ...and I love this..."it's against the law for you to change your pressure" but when asked to prove it they can't because it isn't against the law for the patient to change anything but it is against the law for the DME to change something without okay from the doctor. We don't have to abide by laws meant for DMEs.

Up to you how you want to handle it. Some people are fearful of rocking the boat and prefer to wait until any compliance monitoring is over and done with. Your report isn't horribly horrible...yeah it could stand a little tweaking but it isn't like your AHI is 2 or 3 times an acceptable range. It isn't like your AHI is still in the double digits and your therapy is in the toilet.

Don't ever change anything if you don't understand why you are doing it and what to expect AND are comfortable doing so.
I do it because I am comfortable doing it but not everyone feels like I do and that's okay. If you have a followup visit coming up soon with the doctor and wish to talk it over with him...that's okay too.
Heck, your doctor may have given the DME a bit of leeway with what they are allowed to change (they do it ahead of time) without asking for an okay...sort of like "you can do so and so within this range if you see such and such"...some doctors do that and some don't.

Thanks, Pugsy. I have a one-month follow-up in less than two weeks, so I might just wait until then to do the change. If I continue to see this pattern over the next few days I might try changing the EPR to 1 instead of 2. That at least was not specified on my prescription (APAP 10-14 cmH20 / best fit with / ResMed Quattro Air / Size Sm). After that I probably won't see my pulmonologist until next spring.

Speaking of my prescription, I'm not really sure why he specified the Quattro Air; it is not the mask they used for the titration, and neither the sleep tech at my study nor my doctor ever actually fitted me for any mask. With my leak line, I think it's not the mask for me. I have a 'mask fit" appointment with the DME on Monday to try to get it changed out. I plan to go armed with leak information and graphs so they can't try to blow me off, but I can already tell from my phone call that they're going to try to get me out the door with just a headgear adjustment... After speaking with the folks at our host today, I plan to ask my doc to fax a prescription to cpap.com for "CPAP mask" with no other specifications or limits so that I can take control of my own mask fitting. And if I can't get a scrip from him, I am sure my primary will write the scrip for me. If I have to pay full price out-of-pocket anyway, I have no intention of dealing with the DME over this; Indeed, I think next time I buy a machine I'll do it without involving the insurance company at all.

I don't understand specifying a mask...that just ties everyone's hands...why don't they just say "mask of patient's choice" to leave it open to try any and all masks? Sometimes these docs just left their common sense at home. (If they ever had any )

Though...your leak line is well within acceptable limits unless the leaks are waking you up. Or you just aren't comfortable with the mask... Or unless you have other reports where the leak was much larger than this recent report. Your leak number to avoid is 24 L/min...you never even come close on this report and even if you did meet it or go past it briefly it isn't the end of the world.
If you are thinking you absolutely have to have 0.0 leak...don't go there unless the tiniest of leaks wake you up. It will drive you crazy and it isn't needed.
The machine can do a good job of compensating for leaks up to 24 L/min and even with leaks between 24 and 30 L/min things aren't totally in the toilet. Over 30 L/min for any prolonged duration....then yeah good chance of a problem.

Pugsy wrote:Though...your leak line is well within acceptable limits unless the leaks are waking you up. Or you just aren't comfortable with the mask... Or unless you have other reports where the leak was much larger than this recent report. Your leak number to avoid is 24 L/min...you never even come close on this report and even if you did meet it or go past it briefly it isn't the end of the world.

Well, you've only seen about 12 minutes of the report. The full report looks like this:



And this was actually one of my better nights, leak-wise (though AHI-wise it was the worst since my first night).

I didn't catch the fact that the leak line was a snippet.
I see what you mean but you know the worst of it was between 2:40 and 3:00 ...the rest of the time it was up and down but for the most part within acceptable limits. I see 20 to 30 minutes in big leak myself...though not often quite as big as yours was in this report. I don't worry about them because I sleep through them and for the most part the leaks are well below big leak territory...my bad nights with bad leaks all night are very rare and usually from my opening my big mouth since I use a nasal pillow mask. I sure don't want to go to a full face mask to maybe fix 20 minutes of big leak that might happen once a month. Not even going to consider it.

I do see what you mean with yours though and that much leaking is very likely to be impacting sleep quality to some extent even if it didn't wake you up. I don't blame you for looking at alternative masks.
What did you have in mind to try? You know I have a few donated masks that are either gently used or never used. Don't have a big supply but if your DME or doctor gives you a lot of grief over trying a different mask check with me about what interests you and maybe I have one. If I do and you try it...all I ask is cover my postage costs because sending this stuff out adds up and if you end up hating it...offer it to someone else on the forum so it doesn't go to waste or send it back to me and I will pass it along again.