Variable Breathing

finallyrested · Post by **finallyrested** » Mon Jun 06, 2005 7:21 pm

I just downloaded Derek's program to beta test it. It is great. However, it has raised a question. He has a chart of "Variable Breathing". This is something that I have never seen addressed before. Can anyone out there tell me what it means and what is normal?

Thanks

PS - This is a great site and a great group of members.

neversleeps · Post by **neversleeps** » Mon Jun 06, 2005 10:00 pm

Hi. I found a previous thread where Derek addressed this question. Click on:
Fraction of Night in Variable Breathing

IWannaSleep · Post by **IWannaSleep** » Mon Jun 06, 2005 10:46 pm

In Dereks quote from the Respironics patent it says variable breathing concists of "...When a patient is awake, in REM sleep, or in distress, breathing tends to be more erratic..."

At the risk of over simplification, apparently there are 3 components to variable breathing.The being awake component could be a good or normal thing, the REM sleep component is definitely a good thing, but the distress part probably is caused by an apnea or a hypopnea. The reason this gets complex is the software has to determine which times are distressful times. It then has to decide if it's cause is an apnea or hypopnea. Since it's doing all this from what it can detect through the hose, I maintain it's highly prone to error. The only thing it knows with a fairly high level of accuracy is that it's detecting variable breathing.

This being said, a certain % of variable breathing is a good thing. Certainly there is time at the beginning of the night and again as you're waking up the next morning when you are awake and the machine detects variable breathing. There also is REM sleep, and we all would agree a lot of this is good. It would be interesting to know if there is an optimum % of the night for REM sleep. From the class I had on sleep apnea, I came away with the impression that the more REM sleep you get the better.

In my case, most of my detected apneas/hypopneas occur as I'm falling asleep and as I'm waking up. It's very pronounced in the encore plots. There is such a direct correlation to nights I had trouble falling asleep and mornings when I lay half awake trying to fall asleep again for an hour or more that I strongly suspect my machine is incorrectly interpreting my variable breathing at those times as apneas and hypopneas.

As example, last night I fell directly to sleep and had a solid 7 hours of very peaceful sleep. over those 7 hours the machine only detected 15 events for an AHI during that period of 3.7. after the 7th hour I began to wake but tried to fall back to sleep again for 41 minutes. I kept looking at the clock and closing my eyes hoping for more sleep but finally gave up. During that 41 minutes my machine decided I had 18 additional obstructive apneas. Adding the events during these 41 minutes to the nightly total raises my AHI to 6.0. Looking through my data I see this pattern every night, with the nights I have trouble falling asleep being my nights with highest overall AHI as I see a bunch of events being detected during the hour or so it takes to fall asleep.

My conclusion to all this is you need to be very careful how you interpret the numbers you see coming from your machine, especially taking AHI, as your machine calculates it, as the final say in whether your treatment is successful. This is also why, I believe, the technicians, doctors, and equipment manufacturers encourage you to have your data professionally interpreted vs. taking it at face value from the machine.

I am not a doctor or sleep specialist, only an engineer and mathematician, so take all this for what it's worth. Just one cpap users opinions.

Ron

derek · Post by **derek** » Tue Jun 07, 2005 3:53 am

IWanna,
I agree whole-heartedly with what you say. especially on the Variable Breathing - some is apparently a good thing (REM). I included it in MyEmcore because "it is there", amd because (according to the patent) it is used as one of the "control layers" in the Auto's pressure control algorithm.

I also agree with being very careful on interpreting all data...

When I get a few minutes sometime I will write a simplified description of the control algoriihm. It's quite interesting (and complex) - the most surprising thing is that snores dominate over all other sleep disturbances in controlling the pressure.

IWannaSleep · Post by **IWannaSleep** » Tue Jun 07, 2005 10:24 am

Derek,
I'm glad you included the variable breathing data, it's helpful to me to see the various parameters.

I would also be interested in a simplified write-up of the control algorithm, and I would expect it to be very complex given what the machine is trying to do. Your comment on snores is surprising, until you think about it a bit, since snores are probably one of the primary pieces of data they can detect with certainty. There must be a correlation they can make between snore characteristics and apnea et.al.

Ron

neversleeps · Post by **neversleeps** » Tue Jun 07, 2005 10:39 am

I, too, would be very interested in the Respironics algorithm information because I'd like to compare it to the PB algorithms! I really want to know what is so different about these manufacturers indices that allows for some users to experience runaway pressure with the REMstar auto and not with the 420E.

But that means I've also got to find someone to explain the PBs control algorithm..... Oh well, it was a thought.

ozij · Post by **ozij** » Tue Jun 07, 2005 12:59 pm

Acutally, -SWS had a number of very interesting posts exactly on that - they'er as good as a personal seminar on the subject.

A search for -SWS (the minus is part of his name) and 420 should get you going....

Enjoy.
O.

Guest · Post by **Guest** » Mon Sep 26, 2005 8:15 pm