What's going on here - OSCAR attached

[Bobo97272]

What do you think is going on here?
I went to bed and the only interruption I was aware of was that sometime around 2:20 I adjusted my mask (turned off my resmed 11 for a couple of seconds) then went back to sleep for the rest of the night.
Looking at my OSCAR report a couple of days later I was suprised to see so many events concentrated in the period of 1:20 to 2:20. There were 59 events in that one hour period, and then no events for the next 5 hours when I got up for the day.
I've attached the full night's OSCAR, and the expanded look at the period between 1:20 and 2:20.
What do you think is going on?

whole night Jan 14.jpg (156.7 KiB) Viewed 963 times

part night Jan 14.jpg (146.01 KiB) Viewed 963 times

[Miss Emerita]

I'm going to guess you had a positional problem. Either you usually sleep on your side and turned onto your back during this hour, or you tucked you chin down toward your chest, whether on your side or on your back.

If it doesn't happen again, don't worry about it, but if you see clusters of obstructive apneas from time to time, there are two things you could try. First, if you use a high pillow (or several pillows), try using a single, low, firm pillow. Second, if that doesn't work, you could try using a soft cervical collar to keep your head aligned properly.

By the way, despite the labeling, you were not having Cheyne-Stokes breathing, which is a very particular kind of periodic breathing.

[robysue1]

I'll be honest, this is a set of data that I'd love to see Rubicon's take on.

I agree with Miss Emerita that even though Oscar labels the stretch as "Cheney Stokes" respiration, it's not that. It definitely some kind of periodic breathing, but that's not actually saying much.

Miss Emerita's question about whether you might have been on your back is pertinent since some people's apnea is significantly worse on their back.

But you are also maxed out at 20cm of pressure. And your breathing is not stabilizing at all in spite of that much pressure. And the machine is scoring a heck of a lot of flow limitations at the same time.

If this is the first time you've ever seen this and it doesn't happen again in the near future, I'd be inclined to write it off as a visit from Pugsy's aliens. But if you see this more than once in a blue moon, it's worth asking your doctor about what might be going on when you have this kind of a bad stretch of events.

Any chance you might have been dozing very lightly before you woke up around 2:30?

[Bobo97272]

To respond to some of your questions,
I use a fairly flat soft pillow, my bed partner insists that she's NEVER seen me sleeping on my back. (I can't lie prone in the sand at the beach because of pain). So, it's highly unlikely that I was prone for that hour.

Yeah, I'm not alarmed at the CSR evaluation. My cardiologist tells me that I have a slight murmur, some sporadic PVCs, and a touch of well treated high blood pressure.

What I am concerned about is the length of the obstructions, some that are 30-40 seconds long and yet did not arouse me, which I would have thought would have happened. It's almost as if I were unconscious.

BTW, short of a statin and a blood pressure pill (taken in the morning), the only other drugs I use would be Advil and I haven't had any of that for at least 48 hours prior to the night this happened, I also do not drink alcohol.

So I'm at a loss to explain what is happening (my reason for asking the experts here)

[Bobo97272]

zoomed part night Jan _015.jpg (93.03 KiB) Viewed 902 times

[ozij]

If you click on the "events" tab you'll get a precise list of when and how long each type of event was.

A number of things stand out:

• The machine identified tremendous flow limitation during the time that it raised the pressure to its max
• In the apnea you focused on, there seems to be a diminished drive to breath: you can see the flow dwindling gradually. It looks like that for the other apneas in this series as well.
• You never reach that very high pressure except for that period.

Has the machine ever taken you so high in the past?
I think we should ask what in world those sudden extreme flow limitations really were - since it's they, and not apneas that were driving the pressure so high.
If those extreme flow limitations were something misidentified by the machine, then it's possible your periodic breathing was a response to pressure that was too high for what you really need. It's CO2 in the blood that triggers the urge to breathe. With pressure that drives too much CO2 out of your blood, you simply don't initiate the next breath. Looking at your periodic breathing what I see is a cycle of "deep breath, dwindling breaths, pause, and then another deep breath; repeat". That sort of fits with a response to pressure that is too high. And maybe the pressure got too high because of something the machine mis-identified.

[Bobo97272]

If you click on the "events" tab you'll get a precise list of when and how long each type of event was.

Between 1:20 and 2:20 there were 46 obstructive events. Durations ranged from 10 sec to 55 seconds. There were 15 events that lasted more than 40 seconds.

A number of things stand out:

• The machine identified tremendous flow limitation during the time that it raised the pressure to its max
• In the apnea you focused on, there seems to be a diminished drive to breath: you can see the flow dwindling gradually. It looks like that for the other apneas in this series as well.
• You never reach that very high pressure except for that period.

Has the machine ever taken you so high in the past?

No, it has not (to the best I can recall)

I think we should ask what in world those sudden extreme flow limitations really were - since it's they, and not apneas that were driving the pressure so high.
If those extreme flow limitations were something misidentified by the machine, then it's possible your periodic breathing was a response to pressure that was too high for what you really need. It's CO2 in the blood that triggers the urge to breathe. With pressure that drives too much CO2 out of your blood, you simply don't initiate the next breath. Looking at your periodic breathing what I see is a cycle of "deep breath, dwindling breaths, pause, and then another deep breath; repeat". That sort of fits with a response to pressure that is too high. And maybe the pressure got too high because of something the machine mis-identified.

Yeah, I don't know what the machine could have mis-identified to cause the pressure to jump to 19-20 from my usual 10-11.

I'm not fully understanding your remark about excessive pressure "driving CO2 out" and subsequently suppressing the "urge to breath". If the "urge to breath" were suppressed the apneas should have shown up as clear airway events, but they were clearly identified as obstructive. Or possibly I'm not understanding your point.

Does increasing pressure lower the CO2 level?

By the way, when I woke up that morning, I felt like I'd had a really good night's rest, so I was actually shocked when I saw the OSCAR report a day or two later.

[ChicagoGranny]

By the way, when I woke up that morning, I felt like I'd had a really good night's rest,

If I felt energetic with no excess sleepiness throughout the day, I would get on with life and ignore the graphs unless it happens again.

Worrying about something that didn't cause a problem, is like paying a debt you don't owe.

[robysue1]

I think we should ask what in world those sudden extreme flow limitations really were - since it's they, and not apneas that were driving the pressure so high.
If those extreme flow limitations were something misidentified by the machine, then it's possible your periodic breathing was a response to pressure that was too high for what you really need. It's CO2 in the blood that triggers the urge to breathe. With pressure that drives too much CO2 out of your blood, you simply don't initiate the next breath. Looking at your periodic breathing what I see is a cycle of "deep breath, dwindling breaths, pause, and then another deep breath; repeat". That sort of fits with a response to pressure that is too high. And maybe the pressure got too high because of something the machine mis-identified.

Yeah, I don't know what the machine could have mis-identified to cause the pressure to jump to 19-20 from my usual 10-11.

I'm not fully understanding your remark about excessive pressure "driving CO2 out" and subsequently suppressing the "urge to breath". If the "urge to breath" were suppressed the apneas should have shown up as clear airway events, but they were clearly identified as obstructive.

The test that Resmed machines (as well as the test that PR machines) use to decide between scoring something as an OA or a CA is not always accurate. For example, when I consciously hold my breath while awake, my machines (both Resmed and PR) have always been more likely to score it as an OA rather than a CA.

My best guess is that sometimes a machine can be "fooled" into scoring an OA if the epiglottis has closed over the airway, which happens when you swallow. And I vaguely recall that as the pressure increases, the machine is more likely to mis-score a CA as an OA.

Does increasing pressure lower the CO2 level?

In some people, higher pressure can lead to hyperventilation---i.e. breathing in a manner that causes too much CO2 to be exhaled too quickly. And during sleep, the CO2 trigger for inhalation is reset to be a bit higher than it is when we are awake. Combine the two things and you find that for some people, higher pressure can in fact lead to strings of CAs being scored. For most people, this is not a serious problem, and even for many of the people who do experience so-called pressure induced CAs, the problem is often self-limiting and will resolve itself given a bit of time.

But you've been on xPAP for a while and this kind of thing is new for you. So it's worth pondering whether you should do something and if so, what is a reasonable thing to try.

My advice on what to do is based on the fact that you say:

Yeah, I don't know what the machine could have mis-identified to cause the pressure to jump to 19-20 from my usual 10-11.

If your usual 95% pressure setting is around 10-11 and these strings of events start happening when the pressure has maxed out at 20cm because the machine is scoring your possibly unstable breathing as "flow limitations", then it's worth setting a max pressure setting specifically to prevent the machine from potentially unnecessarily increasing the pressure to the point where your breathing clearly becomes unstable and there is a real possibility that the events are central mis-scored as obstructive.

If this were happening to me, I'd set Max Pressure = 12 or 13 and run with that for at least a week or so. If you don't see this pattern re-emerge, I'd suggest keeping the Max Pressure a bit (1 or 2 cm) above the 95% pressure level as long as the overall AHI is ok and you're feeling ok.

On the other hand, if you continue to get long strings of events when the pressure is maxed out at 12 or 13, then you may need to experiment with increasing the Max Pressure a bit. Or you may want to experiment with increasing the minimum pressure a bit---that helps prevent the breathing from deteriorating enough for the machine to think a drastic pressure increase is needed. And if neither of those helps, then it may be time to talk to your sleep doctor and insist that the doc look at some of the detailed data in ResScan if s/he doesn't trust Oscar.

[Midnight Strangler]

What I am concerned about is the length of the obstructions, some that are 30-40 seconds long and yet did not arouse me, which I would have thought would have happened. It's almost as if I were unconscious.

Before I was treated with CPAP, I was having obstructive events longer than that all night long. I never became aware of them. After being educated about apnea, it was apparent I was waking to restart my breathing and then falling asleep quickly. The wake period was so short I never remembered it. Doc said this was very common.

How long have you been using CPAP and OSCAR? If you've never seen this before, it may be a one-off of no medical significance.