Good data but bad sleep?

Hi,
I was wondering........my AHI is under 5, and my leaks are usually under .30 on pressures of 4.4/8.2 on my ResMed Auto Vantage.
Are there situations in which you still don't sleep well because of the leaks, or can I pretty much assume that leaks aren't a problem? Thanks.

Country4ever wrote:Hi,
I was wondering........my AHI is under 5, and my leaks are usually under .30 on pressures of 4.4/8.2 on my ResMed Auto Vantage.
Are there situations in which you still don't sleep well because of the leaks, or can I pretty much assume that leaks aren't a problem? Thanks.

IMO, your leaks are a bit on the high side for your Swift mask and relatively low pressure. However with an AHI under 5, your Vantage could be arousing you out of deep stage sleep by having it set 4.4 to 8.2. Reducing the spread could help with that.

When I used to use the Vantage I noticed that my sleep quality was better when the pressure range was only about 2 cm (11 to 13 for me). If your sleep lab study did not show you as being sensitive to central apneas I would raise the upper pressure by 1 or 2 cm and trial it for a week between restes just to find out what pressure you do best at ... since it is not uncommon for sleep lab titrations to be wrong. If your sleep lab study did show centrals, you would want to be much more careful about raising the pressure.

Do you have the software?

I also found this thread with leak rates:

viewtopic.php?t=25761&highlight=mirage+ ... eb29980d00

If your leak rate on your Resmed LED is .3 l/sec and the mask is put in the menu correctly, your leaks are .3 l/sec * 60 sec/min or around 18 liters/min above the flow rate for your mask.

Assuming your pressure is 8 and you are using the swift and you have the correct mask in the cpap menu, then your leaks are really 29 (from the chart you posted) + 18 (from the calculation above) or into the upper 40's.

The leaks are excessive imho. Reason needs to be investigated.

I'm not a pro, I've only been on CPAP just over a year but I would wonder about the minimum pressure range being too low.

I readjusted my apap for that very reason. It was set from the dealer to 4 - 20. My titration showed 8 and my machine was rating me at 90% @ 8.3, so I changed my minimum to 7 and max to 15.

I sure do NOT understand your reasoning at all, Jules. Nor your math. That mask is purposely manufactured for a vent (or allowed) leak rate so the only leak rate that matters is the reported leak rate if the Mask Selection option is for the Swift. So if the reported leak rate is .30L/s where are you coming up w/the upper 40s as a leak rate?

Country4Ever hasn't stated what the median pressure has been so you can NOT assume that half the night or any other portion of the night is spent at less than 8 or 8.2 cms of pressure.

I'd be more inclined to follow DreamStalker's line of reasoning.

I think Jules was just trying to give an example on how to evalute a leak rate using the assumption of a leak "usually" under 0.3 l/s and pressure "usually" under 8 cm for a ResMed/Swift setup.

At pressures at or under 8 cm the Swift mask leak rate given by a ResMed LED should be around 0.1 l/s IMO ... others may disagree and could be right. The only way to really tell is by looking at the nightly data to see if the leaks are fairly stable and constant or jumping around all over the place.

That is why I said a "bit" on the high side only. Without looking at the nightly plots, the 0.3 l/s may or may not be a problem.

jules wrote:If your leak rate on your Resmed LED is .3 l/sec and the mask is put in the menu correctly, your leaks are .3 l/sec * 60 sec/min or around 18 liters/min above the flow rate for your mask.

Assuming your pressure is 8 and you are using the swift and you have the correct mask in the cpap menu, then your leaks are really 29 (from the chart you posted) + 18 (from the calculation above) or into the upper 40's.

The leaks are excessive imho. Reason needs to be investigated.

The only data we were given was .3 for a maximum usual leak number, and a pressure range (no mean, median, 90 %ile or anymore data on the pressure - just a range - kind of hard to know what the pressure really is from just a range). The chart used in the provided url starts at 8. I chose in my example to use 8.

I still feel that given the information provided, the leaks are excessive agreeing with DreamStalker. They are not super excessive, but excessive enough to investigate why (around 60 % higher than expected leak rate). For a lower pressure than 8 and the leak rate of .3 on a Resmed LED panel, I would find the leaks slightly more more excessive (measured relative to the expected leak rate of the mask).

All of this goes in the trash if the mask used is a hybrid with a higher flow rate than any of the Resmed masks available in the menu.

The excessive leak rate might be from mask leaks during the night, some mouth breathing, some taking the mask off during the night to make a pit stop, or other reasons. I sure can't comment on why. I agree with DreamStalker that a graph of the leak data over the night would be very helpful.

The problem is that the leak rates for the mask chart as well as the resmed site (manufacturer of swift) are given in Liter/Minute. The LED panel for the Resmed machines gives EXCESS (over the mask put into the mask menu on the machine) in Liter/Second.

One has to convert the numbers to be able to understand the LED numbers in terms on the provided chart. It is kind of like converting between Fahrenheit and Celsius- you have a formula and learn how to use it. In this case there is a different formula for each mask, pressure combination.

for example: leak rate in liter/min is 29 + 60x for pressure of 8, swift in the menu on machine, x is the excessive leak rate

and none of these numbers have a lot of significant digits attached to them and the 29 isn't super accurate as I got lower than that with my old swift on my Remstar at 8, hence I said only upper 40's not 47.

Duh, Jules!!! I never noticed the Swift leak rate chart gave the vented leak in L/m!!!! I figured it was in L/s like via the LCD screen and software. NOW I better understand your math!!! (Math never was my forte tho). Thanks for the explanation.

Thanks everyone,
I wish I was dealing with a better brain right now. It seems to be rotting.
No, I don't have software.
I tried going up on the upper pressure, and it woke me up alot, plus it seemed to kick in when I coughed and would stay up and it was very uncomfortable. When I went up on the bottom pressure, it also felt uncomfortable.
My doc looked at those leak numbers and thought they were fine, but I'm starting to realize that he's not really up on things.
I think I will focus on stopping the leaks. I'm not sure how, since I just can't stand one more thing around my face/chin/head. I guess I'll read up on all the "how to deal with leaks" posts. Thanks.

Determining the leak rate with Jules explanation is much easier than using the Navier-Stokes equation in polar coordinates

that looks like cylindrical coordinates to me but I guess my math sucks

jules wrote:that looks like cylindrical coordinates to me but I guess my math sucks

Woops ... yep, my bad ... my math sucks worse

So if I understand you correctly, a leak, which can lead to infinity(x)+excess(y)/pressure(P)=Lexus? Well they are made by Toyota which is from Japan. Japan is close to Asia. Asia is the contenant that contains China. China puts lead in everything they sell to America. Your leak is caused by lead poisoning. GET RID OF THAT MASK!!!

Of course, i've been know to be bad at coming to conclusions based on mathmatical data.