Can someone tell me how the machine measure my AHI?

I am using the DeVilBiss IntelliPaP machine. Does anyone knows how it measure my AHI? The reason why I ask is I had increase my cpap 0.5cm water above the 95 percentile measurement when the machine is in auto. Pysiologically my windpipe should be fully open. And I don't know why my AHI came back to 5 last few days and before they were around 2-3. Can someone help? Thanx

Midas,

Try this link for a lengthy clinical explanation. http://www.devilbisshealthcare.com/file ... erview.pdf

Larry

Midas wrote:I am using the DeVilBiss IntelliPaP machine. Does anyone knows how it measure my AHI? The reason why I ask is I had increase my cpap 0.5cm water above the 95 percentile measurement when the machine is in auto. Pysiologically my windpipe should be fully open. And I don't know why my AHI came back to 5 last few days and before they were around 2-3. Can someone help? Thanx

Let's see if I understand what you did:
You a an Auto setting, with a minimum pressure and a maximum pressure.

You increased your minimum pressure to 0.5 cms above the machine' reported 95th percentile.

The 95th percentile pressure means you only spend 5% of your sleep time at higher pressure. You spend 95% of you night at that pressure, or pressure that is lower than that.

If you did indeed set the minimum (or fixed) pressure at 0.5 cm h2o above the reported 95th percentile then the pressure you set is too high for your needs. This may either cause non-responsive apnea (are you using the software to see your results?) or disrupt you sleep - and the disruptions may register as added events.

ozij wrote:

Midas wrote:I am using the DeVilBiss IntelliPaP machine. Does anyone knows how it measure my AHI? The reason why I ask is I had increase my cpap 0.5cm water above the 95 percentile measurement when the machine is in auto. Pysiologically my windpipe should be fully open. And I don't know why my AHI came back to 5 last few days and before they were around 2-3. Can someone help? Thanx

Let's see if I understand what you did:
You a an Auto setting, with a minimum pressure and a maximum pressure.

You increased your minimum pressure to 0.5 cms above the machine' reported 95th percentile.

The 95th percentile pressure means you only spend 5% of your sleep time at higher pressure. You spend 95% of you night at that pressure, or pressure that is lower than that.

If you did indeed set the minimum (or fixed) pressure at 0.5 cm h2o above the reported 95th percentile then the pressure you set is too high for your needs. This may either cause non-responsive apnea (are you using the software to see your results?) or disrupt you sleep - and the disruptions may register as added events.

Hi OZIJ,

Allow me to explain a little in detail. I was on auto and the report I got from the smart code was 9.0 cm h2o 90% and 9.5cm h2o 95%. I therefore set the machine to cpap with a fix pressure of 10.cm h2o and the I got a AHI increase from 2 to 5. At the moment I am just using the smartcode only!

The 90 and 95 number are percentiles, not percentages of the pressure you need.

That means you're spending only 5% of your night above 9.5 cm h2o --

If anyone wants to switch from Auto to fixed, they should take the 90%tile or 95%tiles pressure and use them.

The 90%tile pressure means you are spending 90% of time at that pressure, or a lower pressure.. For all you know, you may spening 80% of the time at a pressure of 6, another 5% of the time at 8 and another 5 at 9cm h20. That would give you a 90th percentile of 9.

And here you are, making the machine give you a pressure of 10 cm h20 for 100% of the time - not good. That is not the way to use the information from an APAP.

(edited for typos...)

Hi ozij,

Now I understand what percentile is, left school so long!

Thanks again for your help and I will switch back to auto for safety!

ok first you will need some tools .an apnea yardstick and a hypoapnea ruler which may be found at your local dme. or try lowes sometimes in the clearance bin.
next lay out your hose and measure it with a standard rule. then divide this measurement by your height.
now multiply by your weight/height ratio.


oh wait april fools day is over??????

never mind

Assume your 95th percentile is 10. That means that 95 percent of the time, you pressure is below 10.

10 is 95% of 10.5. It doesn't mean that your correct pressure is 10.5.


Consider these numbers,

10 11 12 13 14 15 16 17 18 19 100

The 50th percentile is 15. 50% of the numbers are above, 50% are below.
The average is 24.5.