Higher leak rate but lower AHI. What the heck??

Wow.. I've REALLY seen a difference the last few nights. What has changed? I've fiddled with my mask a bit and saw a slight increase on my leak rate. Remarkably, with the increased leak rate I saw a drastic drop in my AHI and specifically my HI. Now, my next question is: how does increased leak rate mean lower AHI?? Shouldn't I be seeing the opposite?

Date Usage Leak AHI AI HI
29-Mar 6:51 0.00L/s 12.8 1.7 11.1
03-Apr 6:40 .08L/s 9.3 0.7 8.6
04-Apr 5:26 .10L/s 6.4 0.3 6.1
05-Apr 7:21 .40L/s 4.6 0.4 4.2

A couple of possibilities ... here's one scenario:

I'm assuming that number is "average leak" which doesn't give you enough data to figure out what's happening. If you have a "large leak" one or more times during the night, most machines stop recording AHI durng a large leak so AHI will seem to have dropped but instead you're getting inadequate treatment.

Is there some way you can get the peak leak?

Mindy

I'm curious did you sleep the same number of hours without awakening during the 4 days of data you have presented? I see the useage numbers for each night and since leak rate is a function of time and AHI is a function of state of sleep (in a manner of speaking) you could have an AHI of zero and a larger leak rate if you never fully reached the state of sleep where hypopneas and apneas are occuring, some obviously are though. An oversimplified example would be If I laid in bed for 6 hours with a somewhat leaky mask and never fell asleep. Your useage is about two hours longer from 4/4/09 to 4/5/09 but your leak rate is 4 times higher. I am wondering if this isn't waking you up just enough to bring you out of a later sleep stage and into an earlier one where your likelihood of events are diminished and spread out over a longer time period. Hence the lower AHI coinciding with the longest useage.

Have you felt more tired or refreshed over this 4 day period?


Cheers


Travis

Excellent points. I never considered that the machine would stop recording during a large leak. I have my card reader coming today, so I hope it'll show more detailed events on the charts.

Travis - that's a great point too. I actually woke up feeling pretty refreshed today. I painted the house all weekend and was dog tired last night. I only remember waking up once or twice to adjust my nasal pillows during the night. It would make sense that, with a higher leak rate, my quality of sleep would decline in turn.

Given these considerations, maybe I should be satisfied with my low leak rate, but AHI around 10 (with Remstar's method of reporting HIs).