Need help with Bipap readings...

[iwant2sleep]

Hi all,

I've been having problems with my machine readings. Since becoming a 'hose head' in November, I've not had the data on my machine show any AHI's until two weeks ago. Now I am getting between 3 and 6 per hour, and it's kinda scary. I took my machine to the sleep clinic last week and they said it was nothing to worry about, but were very vague when I asked 'why now?'

I also asked about the pressure support bar chart. Some nights it is coloured all the way up to the top and sometimes only 1/4 the way up the graph. I wanted to know should I be getting a full bar chart all the time? If so, why on some nights is it so low? Conversely, does a low reading mean that was a 'good night' and my lungs didn't need so much support? Or were they not getting enough due to leaks? Again, vagaries only offered...I've had leaks most nights but only between 7 and 10 litre per min. This I am told, is well within acceptable perameters. Strangley last month I had a week without registering leaks at all but I cannot work out what I did differently (Same mask, same sleeping position) but the pressure support still fluctuated!

If you can shed any light on my questions and confusion I'd be very grateful!!

PS I have a Resmed Stellar 100 bipap machine which I use because of co2 retention due to a severe chest wall deformity.

[PaulaO2]

I don't know about the bar charts but to have NO AHI's until now? That's rare. I'd be more concerned your machine was not recording correctly.

Just before it started to show numbers, did you unplug it or did the power go off?

Also, an AHI of 3 and 6 is not much to be scared about. Anything less than 5 is optimum.

[iwant2sleep]

Thanks for your relpy. It is really the pressure support fluctuations I'm concerned about. Can anyone help me solve the mystery please?

[vsheline]

I also asked about the pressure support bar chart. Some nights it is coloured all the way up to the top and sometimes only 1/4 the way up the graph. I wanted to know should I be getting a full bar chart all the time? If so, why on some nights is it so low? Conversely, does a low reading mean that was a 'good night' and my lungs didn't need so much support? Or were they not getting enough due to leaks?

Hi iwant2sleep

I presume you haven't had any recent change in medications.

Your doctor apparently is not concerned about your sudden development of fairly low AHI numbers after having been virtually AHI free for months. OK, but I suggest you let him know right away if the AHI numbers continue to get worse.

I think your machine is kind of like mine, except instead of the Pressure Support (PS) changing breath-to-breath like on mine, on your machine the PS adapts much more slowly, perhaps changing a little bit each minute.

As as as I know, though, your machine is only able to vary the PS, and not also the Exhalation Positive Airway Pressure (EPAP).

I think a low amount of PS is (in a sense) good, since it means your machine decided you were breathing enough without needing a higher PS value.

How low and how high do you see the PS varying between?

What is the lowest possible value (0?) and highest possible value (37?) of the PS bar on your machine's display?

Also, do you know how low and how high is the PS allowed to go, if it is limited to a smaller range than 0-37?

I've had leaks most nights but only between 7 and 10 litre per min. This I am told, is well within acceptable perameters. Strangley last month I had a week without registering leaks at all but I cannot work out what I did differently (Same mask, same sleeping position) but the pressure support still fluctuated!

If your doctor is only looking at statistical reports rather than the ResScan time plots, then I would suggest that it may be good for you to look at the ResScan time plots (Detailed Data) to try to see what is happening so you can bring it to your doctor's attention.

I suggest you use ResScan 4.2 to look at your detailed data, especially the Detailed Data plots of Leak, and also the time plots of when your AHI events are occuring, and how long each event is lasting (how many seconds).

Maybe the low leak numbers are average numbers, and there are periods in which the leak is much worse, and maybe the AHI events are occuring during those "high leak" times?

Or, looking at the ResScan time plots, do the AHI events happen when the PS is max'ed out and unable to adjust itself higher, in which case maybe your doctor should increase the maximum amount of PS the machine is alowed to use.

Or, since your machine is not able to self-adjust the Exhalation Positive Airway Pressure (EPAP), perhaps your EPAP is a little too low, perhaps recently you have been needing a higher EPAP?

By the way, your profile says your pressure is 9/4. Is 9 the EPAP and 4 the minimum PS?

Take care,
--- Vaughn