why the ramp in pressure??

[dottore]

For some years I've used a respironics M series with the pressure at 8cm, but in recent months I have been waking up in the middle of the night with a headache and have not been able to go back to sleep. I suspected that my apnea has gotten worse and that I might need a higher pressure.

I increased the pressure, eventually reaching 11cm without any improvement and with much drier sinuses. Finally, a few days ago, I bought a respironics series one auto cpap (model 560p) hoping this would solve my problems. Of course it ain't that simple....

There have been some strange things, such as a long cheyne-stokes event and another case where the pressure ramped up to 15 centimeters while I was awake and trying to get to sleep, but I have been able to work thru these by using CFLEX instead of AFLEX and adjusting the relief setting.

But here's one, see the attached plot, that still puzzles me. As far as I can tell I was breathing normally. Blood oxygen levels were good and there were no events. If you look closely at the flow waveform, you can see a suggestion of periodic breathing, but nothing major.

yet my machine, for some reason or other, took it upon itself to ramp up the pressure. It ramped up a total of 5 times, then stopped for a while before it ramped up another 4 times. (I only included a couple of ramps in the attachment).

Does anyone have any idea why it would do this?

I realize that the algorithm used by respironics is very complicated (I read the paper on the Philips website, can't say I understood it all), but what the heck could the machine be sensing that would cause it to ramp?

[Sleeprider]

Your machine increases pressure mainly as a result of flow limitations and snores. The waveform you posted looks pretty decent, although the format could use some help. Expanding Events vertically would make them more visible. In this case we don't need to see the SpO2 graph. It would help a lot to see Flow Limitations, because I'm sure that is why your pressure is ramping up.

I think you're using Sleepyhead. The easiest way to get a detail chart is to use the F12 button which will save the chart to your Documents/Sleepyhead/Screenshots directory. To post the image on this forum, take a look at this tutorial http://www.apneaboard.com/wiki/index.php...pnea_Board

What pressure settings are you currently using? Is Ramp on? If so what is the minimum pressure and ramp time?

Just to put your mind at ease, the event "Cheyne Stokes Respirations" is mis-labeled. It should just be Periodic Breathing (you can change this in File/Preferences/Events and double click on the name to change it.

Turn on the Flow Limitations Events flag in Sleepyhead (checkmark) and you will see the pressure increases coincide with those.

[quiescence at last]

The plot that you posted shows a pressure increase that the machine does on it's own, without sensing any issues or events. the same thing happens every night on the PRS1 unit. it adjusts slightly, and exactly the same way each time.

I am quite sure it has nothing to do with flow limitations, etc.

see below chart, early in the night where it goes up and down regularly...




QAL

[Sleeprider]

The plot that you posted shows a pressure increase that the machine does on it's own, without sensing any issues or events. the same thing happens every night on the PRS1 unit. it adjusts slightly, and exactly the same way each time.

I am quite sure it has nothing to do with flow limitations, etc.

see below chart, early in the night where it goes up and down regularly...

QAL

Include flow limitations and snores in the posted chart, and let's talk. Also, the resolution of that graph is barely readable. Take a look at my suggestions above.

[quiescence at last]

yeah it is all I had at the time, but the non-random behavior is still visible from where I stand. I don't believe I could be that regular in my 'snores and limitations'. we all three have the same type machine, and this should be readily confirmed.

if I can find any correlation to these regular bumps, I will post another chart.

[dottore]

working on correcting this post, not sure how to delete.

[dottore]

OK from the posts there seem to be two theories, 1) that there is a flow limitation event to which the machine responds and 2) the ps1 just does that.



I hope this displays the screen shot.

You will see that there IS one Flow Event. But it comes after the 4 ramps. (I record audio and from the audio I can tell that I took a deep breath at 0:15, followed by a stretch and "whine" -- at least that's what my girlfriend calls them). Anyway, the FL could not have caused the 4 ramps since it came after.

no snores, either. I don't snore. apnea but no snores (very, very few anyway).

Thanks much for the replies. and especially thanks for the tutorial on how to do the imgur thing. I wondered how that was done.

as for the rest:
min pressure 9cm
max pressure 13cm
ramp start 8cm
ramp time 45 minutes, but this all occurred after the ramp was finished, so not sure what that has to do with it.

[Sleeprider]

Flow limitations have a significant affect on pressures, but there are other breathing patterns that reflect increased breathing resistance that may explain the bumps in pressure you are seeing. My unit will also bump pressure, sometimes significantly with no apparent cause in the event data. Closer examination may show some breathing irregularities. Only the manufacturer really knows all the elements of its pressure change algorithm, and you can sometimes find those details reading through their patent documents. It's pretty tedious. Maybe someone has studies this in sufficient detail to answer your question.

Here is a link to an article that might offer some insights http://www.sleepreviewmag.com/2009/09/au...-pressure/

[quiescence at last]

from the above link, notice how the REMstar has beats during the 'normal breathing' times, just like the OP.

[dottore]

Thanks for the link to the article. I haven't read the whole thing yet, but found this quote from the article explains what the ps1 is doing:

"Common in the Respironics APAP models is a “hunt and peck” search pattern, as part of the device’s algorithm is to find optimum therapy pressures in the face of airway resistance. The unit will increase pressure by 1.5 cm H2O over the course of 3 minutes and monitor the flow to see if there is an improvement. If there is none, the unit returns to the original pressure within 1 minute."

The pressure ramp in my posted chart is 3 minutes long going up, and 1 minute long falling. It rises from 9cm to 10.4cm and falls back to 9cm. bingo!

I am going to print out that article and read it thru. Probably pick up some good ideas for using my machine. at least I will understand it's limitations.

This is all very interesting stuff, eh?