Interpreting Sleep Statistics

dkeat · Post by **dkeat** » Tue Oct 25, 2005 1:59 am

I looked at my numbers this morning, second night with the Aura. The picture leaves me wondering what to do next, if anything.

Pressure - % of night - obstr. apneas

7 - 59.9 - .4
8 - 20.4 - .6
9 - 4.9 - 2.4
10- 11.4-5.1
11- 2.1 -21.8
12 - 1.2 - 20

I spent the vast majority of the night between 7 and 9 with very few events. As the pressure increased the number of events increased as well. In a very short space of time at 12 (the highest pressure reached) 20 events occurred. I am wondering if all is well with this picture or if I would be better off lowering the top pressure to see if fewer events would occurr. Does anyone out there understand this kind of picture and what it means?

Thanks.

Guest · Post by **Guest** » Tue Oct 25, 2005 6:50 am

Maybe hypopneas at higher pressures?

Set it for 7-10 tonight and see what happens....

stryker5777 · Post by **stryker5777** » Tue Oct 25, 2005 11:32 pm

Yes.. I've also noticed that there seems to be an increase of obstructive and hypo apneas as the pressure goes up. Does anyone know for certain if there's an cause and effect relationship here between the pressure setting and the number? Are higher pressures a response to apneas or are they actually causing more of them in some instances?..

dkeat · Post by **dkeat** » Wed Oct 26, 2005 1:00 am

stryker5777 wrote:Yes.. I've also noticed that there seems to be an increase of obstructive and hypo apneas as the pressure goes up. Does anyone know for certain if there's an cause and effect relationship here between the pressure setting and the number? Are higher pressures a response to apneas or are they actually causing more of them in some instances?..

My concern exactly. Well put.

derek · Post by **derek** » Wed Oct 26, 2005 3:10 pm

I found for myself a rapidly increasing AHI at pressures above 9-10 cm. This was true on both APAP and CPAP. I did a 3 month experiment to map the effect of pressure on my AHI: the picture was identical for APAP and CPAP, leading me to conclude that APAP was not acting pro-actively as advertised, and that my AHI was simply determined by the pressure.

I settled on CPAP at 10 cm, and now have an average AHI of 0.3, which is way better than the APAP results at 9-14cm.

dkeat · Post by **dkeat** » Wed Oct 26, 2005 3:18 pm

[quote="derek"]I found for myself a rapidly increasing AHI at pressures above 9-10 cm. This was true on both APAP and CPAP. I did a 3 month experiment to map the effect of pressure on my AHI: the picture was identical for APAP and CPAP, leading me to conclude that APAP was not acting pro-actively as advertised, and that my AHI was simply determined by the pressure.

I settled on CPAP at 10 cm, and now have an average AHI of 0.3, which is way better than the APAP results at 9-14cm.

derek · Post by **derek** » Wed Oct 26, 2005 3:35 pm

David,
The effect of pressure on apneas/hypopneas is well known, and higher pressures are thought to induce central events in many people.

The Respironics Auto patent states they use a different pressure increase algorithm above 10 cm to account for the fact that the higher pressures can induce apneic events. One of the problems is that increasing pressure can cause a runaway (unstable) situation if you simply increase the pressure hoping to supress apneas. Think about it - if your apnea rate increases with pressure, then an APAP pressure increase will make matters worse, leading to another increase on pressure, etc, etc, and bingo you hit the upper limit.

I have had the chance to look at several people's AHI vs pressure curves while debugging MyEncore. Some people show a definite minimum (like me), while others do not. In one case the person showed a steady increase from 5cm, which made me wonder why he was using CPAP at all.

snoremonger · Post by **snoremonger** » Wed Oct 26, 2005 3:52 pm

I have been wondering the same as when I use my machine in auto mode I am waking up taking my mask off mush earlier in the night than when it's on straight cpap. I don't know what the pressure gets up to but when I pull the mask off it is blowing much more than my prescribed 9cm.

I don't have a reader or software but am also curious as to what the pressure is doing in auto mode.

neversleeps · Post by **neversleeps** » Wed Oct 26, 2005 4:53 pm

Occasionally, an individual's particular breathing patterns are not interpreted correctly based on the algorithms used by a particular auto. If you're always topping out at the max pressure no matter how high you're setting it, perhaps this is what's happening to you. On the other hand, if you're topping out at the max pressure AND your AHI is not going up, maybe you actually need it.

Once you've conducted some self-titration experiments, if you determine this issue is a function of the machine's misinterpretation (and not due to your needs), you'll be able to either narrow the auto range with a cap on the top pressure to a figure that works best based on your results, or use the auto in CPAP mode.

Here is derek's thread discussing the above mentioned experiment he conducted:
CPAP is better than APAP (for me..)

dkeat · Post by **dkeat** » Thu Oct 27, 2005 12:03 am

This is an important subject and it seems that the correct handling of it is vital to achieving optimal results. I'm going to check out Derek's thread CPAP is better than APAP (for me..) and see if I am any wiser after that. It would be great to have a precise protocol to follow to establish an optimum pressure and mode (auto or cpap). Apparently some people do best with apap and some with cpap.

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Interpreting Sleep Statistics

Interpreting Sleep Statistics

Increasing Pressure