Hi all,

I have lost a ton of weight (55lbs) and my doctors and I were having trouble keeping me asleep (assuming titration was off).

So, just yesterday is got upgraded from the Resmed S8 Escape CPAP to the Resmed S8 Autoset Vantage APAP.  With my old unit, I never had access to data before, so I was wondering if you could educate me on what the numbers mean.

Press: 11.4  (I know what this is, my last titration of CPAP called for a pressure of 13cm/h20)

AHI: 4.1  Isn't this really, really low?

Leak: 0.08L/s

AI: 0.1  I assume this is apnea events / hour

HI: 4.0  I assume this is hypopnea events / hour

I didn't really sleep any better last night than I have been, but that's a one night sample.  I'm wondering from the low AHI value if I even need treatment any longer?

An AHI of 4.1 is good (below 5 is good), but it isn't even really low.

The AHI is the sum of the HI and AI.   AHI of 4.1 is quite good but could get better.  It does depend on a lot of things - diet, stress, mask leaks.  It also sounds like there was trouble getting the titrated pressure.  That is a problem for most of us since sleep studies are difficult. I've just been doing this data analysis for a little over a month and I have had AHI from 1.1 to 6.  The leak rate can depend upon what mask you are wearing.  The machine compensates for leak levels for different masks.  If your  mask is too tight or too loose, there will also be leaks.  All these types of leak affect you Apneas, Hypoapneas and, of course, the total, the AHI.  You mask documentation should tell you what is an acceptalbe leak rate for that mask at a specific pressure.  Does your data show 0 large leaks?  I am not familiar with your machine and am going by mine (which is also and auto) and the data from it.  You're right, one night is not enough to get a real reading.  You need to chart it for at least a week and get an average.  I would say, with an AHI of 4.1 and a possible presure of 11.4, you still need treatment.  My titration pressure is 11.

Big Ed wrote:

I was wondering if you could educate me on what the numbers mean.

The biggy...AI is 0.1 and that is great.  ResMed machines tend to overscore the HI due to the algorithm.


From the manual:

ResMed wrote:

An apnea is defined as a greater than 75% decrease in ventilation. The device algorithm scores an apnea if the 2-second moving average ventilation drops below 25%
of the recent time average (time constant 100 seconds) for at least 10 consecutive seconds.

A hypopnea is defined as a 50 to 75% drop in ventilation. A hypopnea is scored if the 8-second moving average ventilation drops below 50%, but not below 25%, of the recent average for 10 consecutive seconds.

Note: When EPR is enabled, detection of apneas and hypopneas may become less reliable at high levels of leak (> 0.4 L/s — 24 L/min).

Big Ed wrote:

I'm wondering from the low AHI value if I even need treatment any longer?

Your numbers are low because of your treatment.  You wouldn't have those numbers without the mask.

BarryKaraoke wrote:

Your numbers are low because of your treatment.  You wouldn't have those numbers without the mask.

That makes sense, thanks.

Is the leak number good, bad, or indifferent at 0.08?

Big Ed wrote:

Is the leak number good, bad, or indifferent at 0.08?

You'd need to compare that to the expected leak rate for your mask at your pressure. Every mask has some leakage through the exhalation port. I'm only on my second mask, but 0.08 L/s seems very low. The two masks I've tried have leak rates around 20-30 L/min (0.33 - 0.50 L/s) at pressures around 10-12 cm. What mask are you using? Is the exhalation port working properly (not blocked or clogged)?


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Respironics Auto M Series, Pressure: 12 cm
Fisher & Paykel Opus 360 Nasal Pillows
My Sleep Blog

Ultra Mirage Full Face mask.  The port is working properly, although I sleep on my stomach so the pillow may partially obscure it.

Where would I find the expected leak rate data?

Look for the leak rate data in the manual that came with your mask.


_________________
Respironics Auto M Series, Pressure: 12 cm
Fisher & Paykel Opus 360 Nasal Pillows
My Sleep Blog

I found the manual on the ResMed website: http://www.resmed.com/en-us/products/service_and_support/documents/608136r1_ultramirage_ffm_userguide_us_multi.pdf

The flow rate for that mask at 11 cm should be around 35 L/min (.58 L/s). You may be blocking the port which would reduce your oxygen supply and disrupt your sleep.


_________________
Respironics Auto M Series, Pressure: 12 cm
Fisher & Paykel Opus 360 Nasal Pillows
My Sleep Blog

Uh oh, I wonder if that was my problem all along.  Guess I should learn to sleep on my back.

Resmed machines have the leak rate of the mask built into the data.  If the expected leak rate of your mask is 30 and your actual leak rate was 30, then the results will show 0.  The 0.8 you are seeing is the leak rate above the 30 expected.

Thanks, jleslietx.

Ed, disregard my previous posts!  


_________________
Respironics Auto M Series, Pressure: 12 cm
Fisher & Paykel Opus 360 Nasal Pillows
My Sleep Blog

Thank you very much!