machine stuck on AHI / Large Leak 0

[patrick_a]

Hi All,

I found a few older post about this issue, but I'm not sure if my machine is broken or ?

My 1,7 and 30 day AHI is at 0.0. My AHI was relatively low anyway; and dropping, but more telling is my Large Leaks is also been at 0 for many weeks. Btw, I unplug my unit everyday.

I was assuming if the the pressure transducer stopped functioning the unit would flash an error code. Maybe this is not correct... anyone know? Is there some way to test my cpap unit to know if there is a serious problem? It does seem to be functioning perfectly otherwise... and I cannot use the "how I feel" barometer because I have another health issue with some identical symptoms.

Somewhat related: saw a S9 Autoset w/humidifier (~1000 hrs) for $300. The hours seem a bit high to me, but assuming 8 hrs a night usage, that is around 4 mos worth. I don't know... any advice from you experienced S9 users?

Thanks.

[robysue]

On a PR machine it is NOT unusual to have a Large Leak % equal to 0 for weeks (or even months) at a time. Typically a Series 60 System One is not going to flag a large leak unless the leak rate is above 60-70 L/min and the Series 50 machines don't trigger large leaks until about 80-90 L/min. Look at your leak lines in Encore or SleepyHead. If they are always under 60 L/min, that explains why you are seeing the Large Leak % equal to 0. (I've had a Series 50 BiPAP for over three years now and I've had three Large leaks reported in Encore that entire time; and I went over a year between the first official Large Leak and the second official Large Leak.)

To give you an idea of what it takes to make the 1-day Large Leak rate show something other than 0, consider this math. Let's assume that you sleep for 7 hours (420 minutes). To see a Large Leak % = 0.1, you have to have a Large Leak that lasts at least 0.1% of the entire night. 0.1% of 420 minutes is .42 minutes, which is about 25 seconds. To have a Large Leak of 1% requires a Large Leak to last for at least 4.2 minutes, or about 4 minutes and 12 seconds. That doesn't sound like a lot, but remember, a large leak is only flagged if the total leak rate is somewhere around the 60-70 L/min range (the actual value seems to depend somewhat on the pressure you are using.) And for people with a decent seal on the mask, it's not that uncommon for all the leaks to be under the Large Leak range.

So look at your leak lines. If your max leak rate is consistently below 60 or 70 L/min, then even the worst of your leaks won't be flagged as Large Leaks. So do you see any periods of time at all with a leak over 60 or 70 L/min? If not, the Large Leak number on the LCD is correct.

As for the AHI = 0.0 for several days in spite of unplugging the machine. I'd look at the data. You say your AHI is usually very low to begin with. So take the time to zoom in on the wave flow and see if you see anything that looks like an apnea or a hypopnea. If not, then trust the number. If you see some things that ought to have been flagged on multiple days with the reported AHI = 0.0, you might wan to have the machine looked at.

[patrick_a]

Excellent info robysue... thank you very much!

I'm still hoping for an Android ver for Sleepy Head as my cell is my only computer. I see there is now a Linux ver, so I hope the Android will be right around the corner

[archangle]

Somewhat related: saw a S9 Autoset w/humidifier (~1000 hrs) for $300. The hours seem a bit high to me, but assuming 8 hrs a night usage, that is around 4 mos worth. I don't know... any advice from you experienced S9 users?

Great price, even with 1000 hours, as long as it's not somehow damaged or defective.

You might try playing around and faking some apneas and seeing if they show up in your data.

[patrick_a]

You might try playing around and faking some apneas and seeing if they show up in your data.

I held my breath a few times followed by some quick hyperventilating to simulate an event. Great news, my 1 day AHI jumped to 10, so my machine looks like it is working well.

Thanks for the help.