Flow limitation

Hi,
I've been doing alot of reading about hypopnea's and how hypopnea's can be different in description by cpap manufacturer by flow limitation.

What exactly is flow limitation ?? How will flow limitation help me anazlyze data from ResScan ??
Thanks

Think of it as a partial hypopnea........a hypopnea "wannabe".......but didn't make it.

Auto algorithms look for them as an excuse to raise pressures......thinking that something "bigger" may happen soon. In reality, many times they don't for many/most of us and it ends up being an unnecessary pressure increase.

Edit: (I forgot your second question) The ResMeds lump all Flow Limitations and Hypopneas in the same category and that's why the HI numbers are higher than they are on a Respironics Auto machine (which does break out both numbers).
The typical advice given on the forum is to cut your HI number in about half to determine the Hypopnea and AHI totals.


Den

Hi Wulfman,
Thanks for reply.

Auto algorithms look for them as an excuse to raise pressures

So flow limitations are vital to auto xpap users ? So more information can be obtained using auto xpap as opposed to straight cpap, with ResScan software. My pressure is set to 10cm now.

How do I set up cpap min/max pressures ?

I am going to try to upload ResScan data shortly using straight cpap.
Thanks

What do your "numbers" (AI, HI and AHI) look like now?
If I understand your post, you DO have an Auto but are using it in straight CPAP mode at a pressure of 10 cm. ?
Are you using EPR? If so, which setting?

Personally, I don't feel that using an Auto in a range of pressures is beneficial for good, sound sleep.


Den

Hi Den,

What do your "numbers" (AI, HI and AHI) look like now?

Here's recent data from lcd display, past 3 sessions
Leak: .02 .00 .02
AHI: 5.0 6.8 2.9
AI: 0.0 0.0 .3
HI: 5.0 6.8 2.6

you DO have an Auto but are using it in straight CPAP mode at a pressure of 10 cm. ?

Correct, never used auto.

Are you using EPR? If so, which setting?

I am using EPR setting of 1

Personally, I don't feel that using an Auto in a range of pressures is beneficial for good, sound sleep.

Can I obtain optimal pressure using auto, with ResScan sofware ??
Thanks

wm:
> In reality, many times they don't for many/most of us and it ends up being an unnecessary pressure increase.

So true. I find the same thing to also be true of Vibratory Snore. That's the biggest complaint I have about my Auto M. I will have no hypopneas or apneas _at all_ (and low FL in the 1.x range) for a couple of hours, and then have a large number of VS and the pressure will then go up.

Are there any tricks/adjustments to make it so that will not happen?

> I don't feel that using an Auto in a range of pressures is beneficial for good, sound sleep.

Isn't that why auto machines were invented, to give more pressure when it's really needed?

As opposed to increasing it just for FL or VS, when it's often not needed.


s:
> never used auto

From your AHI, you should consider it. No good reason not to try it.

Remenber what Woody Hayes, the old football coach, used to say about the forward pass: three things can happen and two of them are bad.

With fixed pressure, three things can happen and two of then are bad. (You need more pressure or you need less pressure.)

With my auto, I spend _hours_ per night under (that is, less than) my prescribed pressure, because it's not needed then. And on a good night I might spend an hour or so above my prescribed pressure. And more hours right around my prescribed pressure.

Spirit wrote:Hi Den,

What do your "numbers" (AI, HI and AHI) look like now?

Here's recent data from lcd display, past 3 sessions
Leak: .02 .00 .02
AHI: 5.0 6.8 2.9
AI: 0.0 0.0 .3
HI: 5.0 6.8 2.6

you DO have an Auto but are using it in straight CPAP mode at a pressure of 10 cm. ?

Correct, never used auto.

Are you using EPR? If so, which setting?

I am using EPR setting of 1

Personally, I don't feel that using an Auto in a range of pressures is beneficial for good, sound sleep.

Can I obtain optimal pressure using auto, with ResScan sofware ??
Thanks

I don't think I've ever tried to dissuade a person from ever TRYING their APAP in Auto mode.

HOWEVER......

With numbers like those (especially the AI at 0 or close to it), it's hard to imagine that a range of pressures is going to be able to improve on them.
One reason is that you're already at a pressure of 10 cm. The ResMed APAPs don't like to go above that pressure UNLESS there is snoring or flow limitations. Otherwise, the algorithm is deliberately designed to avoid Central Apneas, which (apparently) studies have shown will occur more above the pressure of 10 cm.
So, unless you have those precursor events, it will not go higher than 10 cm. Your data is showing that your apneas are being well taken care of by your existing pressure settings. And, based on those results, switching to a range of pressures you would want your minimum pressure at 10 cm.
Based on the "rule of thumb" around here, you could statistically cut your HI number in half and come up with a truer AHI (due to the fact that the ResMed Autos count flow limitations into the hypopnea numbers). And, then, those AHI numbers of yours would look REAL good.

Remember, an APAP has to have an "event" on which to trigger a response.....which WILL raise the pressures and MAY disturb your sleep. If you DO wish to try your machine in a range of pressures, I would advise not setting the minimum pressure below 10 cm. and the maximum pressure no higher than 12 cm. (for experimental/trial purposes)
That range would at least give you SOME idea of what would happen and would keep the pressure changes to a minimum.

Okie dokie?


Den

Spirit, if it were me, I'd try a range of 9-12 and log the results. Using EPR=1 means that when you exhale, the pressure drops by 1 cmH2O. If your AHI rises if you try 9=12, then try 10-12 and see what happens.

I am one who does better on an APAP with much, much better sleep using a wider range than most forum members at 6.8-15. I need to get a card reader or USB adapter to see the detailed data but I suspect I spend a lot of time in those lower pressures.