Numbers and ranges

Hi guys, can some one break down the general meaning of the abreavations- and what the normal or good range of the numbers should be? I just switched to a ComfortGel Mask mask from a full face mask, using a resmed s8 auto set machine- This is what my numbers have been since-

Pres16.2 ( normally 18+ w/ full face)
Leak 0.22 ls
AHI 8.2
AI 0.7
HI 7.5

My numbers were alot higher with full face mask, If I could get ranges and descriptions of AHI, AI, Hi? that would help also. Thanks a bunch!!! Blair

If you post a profile containing you cpapmachine, mask, etc, it will help the experienced members provide comments.

Your leak rate looks about right for a nasal mask with no extra leaks. The numbers you achieve depend on you treatment devise settings.

You can look up definitions here on the forum CPACopedia, CPAP FAQ, etc.

smockb,

When you changed masks, did you change the setting in your S8?

AI = Apnea Index
HI = Hypopnea Index
AHI = Total of Apnea Index + Hypopnea Index

AHI should be less than 5.0 (normal)

I'll let someone else that's familiar with that mask/machine combination comment about the leak rate.

Here's a link to the CPAPopedia (above).

cpapedia.php?mode=view

Den

Leak rate is still way too high, anything over .4L/s (24L/m) will trip the leak alert (if enabled) and result in High leak in last session.

If you multiply your .22L/s x 60 you get Litres per Minute. On that machine when you select the mask from the LCD it automatically deducts the intentional leak rate.

Resmed Clinical Manual, page 37.

After reading snoredog comments, it looks like I misread your leak number. Haste makes waste. Sorry for the bad comment. Sounds like snoredog has made some very good comments.

Much luck!!

curt, actually you were correct about smockb's leak rate looking very good, using a resmed machine.

Any leak rate less than 0.40 l/s is considered acceptable with resmed machines.

Many of us, including me, have gotten the decimal point in the wrong place before! Easy to do.

http://thorax.bmjjournals.com/cgi/reprint/61/3/226.pdf

On page 3, in the section "CPAP data" of that study using resmed machines:

"a 95th centile leak of <0.4 l/s was considered acceptable)." (emphasis mine)

95th centile means that amount OR lower 95 per cent of the time.

Snoredog's right about how to convert liters per second to liters per minute. resmed machines and Puritan Bennett machines calculate leak in liters per second; however, Respironics calculates leaks in liters per minute. That's always good to know when comparing numbers people get from different manufacturers' machines.

To add to confusion... even though resmed machines report leak as liters per second, the charts resmed encloses in the package with their masks states normal leak flow per minute. Oh well.

rested gal wrote:curt, actually you were correct about smockb's leak rate looking very good, using a resmed machine.

Any leak rate less than 0.40 l/s is considered acceptable with resmed machines.

Many of us, including me, have gotten the decimal point in the wrong place before! Easy to do.

http://thorax.bmjjournals.com/cgi/reprint/61/3/226.pdf

On page 3, in the section "CPAP data" of that study using resmed machines:

"a 95th centile leak of <0.4 l/s was considered acceptable)." (emphasis mine)

95th centile means that amount OR lower 95 per cent of the time.

Snoredog's right about how to convert liters per second to liters per minute. resmed machines and Puritan Bennett machines calculate leak in liters per second; however, Respironics calculates leaks in liters per minute. That's always good to know when comparing numbers people get from different manufacturers' machines.

To add to confusion... even though resmed machines report leak as liters per second, the charts resmed encloses in the package with their masks states normal leak flow per minute. Oh well.

I had my decimal point in the wrong location also, but leave it to Resmed to write it 3 different ways. Actually the manual says if the leak exceeds .4L/s for 30% of the previous session it will result in High leak in last session.

Then it says:
The Leak Alert feature, if enabled, will alert the patient when mask leak exceeds 0.7 L/s (42 L/min) for more than 20 seconds. When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally.

the 0.7 L/s (42 L/min) is the value one should be concerned with as that is where the machine will cease to function optimally.

My experience with Resmed machines was that if I had the correct mask set in the menu, the leak rate would show as zero on the charts. This was certainly the case with a VPAP III I recently did some tests with. I am trying to recall if the same applied on an S7 Spirit & S7 Elite I also trialed earlier this year. I can check that later.

Other than my own observations, I believe the other comments re 0.4 l/s as an acceptable leak rate, seem ok.

I did know someone who kept reporting high leak rate on an S7 Elite that I knew was quite ok & when I looked at what this person was doing it turned out they were using an Ultra Mirage F/F mask but had set the menu for a std mirage nasal mask. The built in leak rate is quite different between these two masks & this person by setting the wrong mask, was not able to get the machine to run for more than a minute without it stopping & reporting excessive leaking.

Cheers

DSM