Measuring HYPOP Events(Fact or Fantasy?)

[roztom]

Hi:

I have a Remstar APAP with C-FLex and Smart Card, etc.

Many of you use the same flow generator.

HAs anyone done any testing to see what creates a Hypopnea as far as the software is concerned?

Derek did some testing to simulate Snores to see how they registered.

Has anyone figured out what registers as a Hypopnea on the software?

If you yawn does that show up? If you swallow or clear your throat does that show up?

I'm just wondering because I laid awake for 4 hours the other night but registered a bunch of snores and about 8 hypop's eventhough I was just laying there on my back thinking about work related stuff. (COuldn't find the off switch )

Any thoughts on this?

Thanks,

Tom

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, C-FLEX, Hypopnea, APAP, Smart Card

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, C-FLEX, Hypopnea, APAP, Smart Card

[alphabettie]

I am interested in this also as I feel like the Hypopnea Queen of The ResMed Vantage. Last night I had a huge sneeze and it registered as a huge leak. I will have to try the yawning and throat clearing to see what actually does register. Good question.
BTW. On another thread, I was discussing my AHI and last night I changed to 11.8 as my bottom level. I had .3 per hour apneas, but 11 hypops. Today I feel on top of the world. Maybe I need to do some more investigating on this subject.

[Titrator]

Alphabetty,

Your hypopnea index number may be high because you are using the Aura Headrest interface. Resmed machines give the most accurate numbers using Resmed masks. They have mask settings for their masks on the machine menu.

When I used a breeze on the VPAP III, the fact that it has nasal pillows and a small 15mm tube, it gave me very high HI numbers.

You may want to get a Resmed mask to do spot checks on your therapy.

Regards,

Ted "Titrator"

[Brent Hutto]

I just flat out don't believe the hypopnea-measuring ability of my Redmed S8 Vantage, if by "hypopnea" we mean the same events that would be labelled "hypopnea" in a full PSG sleep study.

Now I'm open to the possibility that the "hypopnea" measured by the APAP is something related to breathing and sleep disturbance and therefore worth tracking but after 11 nights it seems clear to me that my Hypopnea Index on the APAP is higher when I take longer to fall asleep and/or take longer to go back to sleep after getting up to go to the bathroom. I am almost surely not having 50% flow reduction with O2 desaturation (or whatever definition you want to use of hypopnea) at those times, what I'm having are simply changes in breathing rate and deepness of inhalation/exhalation.

I'm more inclined to believe the "apnea" although without being able to link it to arousals it's still less than perfectly valid. If nothing else, my Apnea Index with APAP 7-12 is about half the residual AI during my titration study with CPAP 9 which makes sense.

Bottom line, for someone with severely fragmented sleep like me (arousals and micro-arousals at a rate of 80/hour even on CPAP) trying to estimate hypopneas from must flow and pressure is a mug's game. It's not that my particular APAP isn't working well but rather the task is impossible.

[Brent Hutto]

Let me add one more observation from my own experience. I write down the numbers I can read off the LCD each morning and the numbers for "Leak" and "Hypopnea Index" pretty much track perfectly. So that means the average rate of what Resmed calls "hypopnea" events during the night has a very strong relationship with the 90th or 95th percentile of leak rate during the same night. Here are those two numbers for nine of the first eleven nights I've used the machine:

0.82==12.4
0.34==11.5
0.40==11.9
0.36==12.4
0.48==9.6
0.90==12.8
0.36==9.7
0.42==11.9
0.58==12.5

I left out two nights where I used a full-face mask for a couple hours (resulting in very high leak numbers) and then switched to the Swift because I don't know what the leak would be for the majority of the night with the Swift. FWIW, those leaks were around 1.2 HI's were around 17.

My idea is that Resmed's APAP uses some calculation of average inspiration and expiration over an interval to estimate "Leak" and then uses a similar average as a baseline for noticing reductions in flow to identify "hypopnea". When the mask leakage (or mouth leakage) gets bad enough there's no longer enough good information to discriminate between "hypopnea" and other kinds of breathing. Or something like that.

[john5757]

The ResMed has a mask selection feature so it knows what the leak rate of the mask is. I am using the ResLink on my S7 Spirit and I can see that mouth puffs register as a Hypopnea when the leak rate is low and there is a spike on the pressure curve. Some of the other Hypopneas occur when the leak rate fluctuates wildly during a short period of time. Other times the machine will register a Hypopnea when nothing else shows on the curves. The ResMed can not tell if a Hypopnea event is central like or a obstruction. The ResMed will not trigger on a Hypopnea unless there is a "flatting" or flow limitation on the waveform. The theory is to react to "flatting" proactively before Hypopnea or or Apneas will occurred. The ResMed will also react to snoring as a reactive response. The third is as I understand it for Apnea events without "flatting" up to 10cm.

P.S. I forgot to mention that the ResMed will not record apnea events unless it is 10 seconds or longer and that the shortest I have seen.


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CPAPopedia Keywords Contained In This Post (Click For Definition): resmed, Hypopnea

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CPAPopedia Keywords Contained In This Post (Click For Definition): resmed, Hypopnea

[roztom]

Thanks for that explanation of the Hypop's.

Tom