Leak Rate Observations Analysis & Questions

I have been comparing data between 3 nasal masks and wonder if my conclusions are accurate:
Variables: Avg pressure = 16.0; Chin strap Data checked daily on Encore VIewer
Leak rate data from manufacturer leak rate charts

Mask
#1 Activa LT
According to published leak rate data should be 40
My avg leak rate is 44-48 with AHI between 3.9-5.5

#2 Comfortgel Nasal
According to published leak rate data should 32
My avg leak rate38-42 with AHI between 3.9-6.0

#3 Fisher & Paykel 407
According to published leak rate data should be about 46.5
My average leak rate 38-40 with AHI between 3.2 - 3.6
The first 2.25 hours the leak rate range was 15-20 then it was consistently about 50 the right of the night

Comfort Level:
The F & P 407 was the smallest mask, most comfortable and easy to adjust
The Comfortgel Nasal was slightly larger and comfortable and adjustment was relatively easy
Activa LT - my DME claimed this would be the most comfortable and easiest to adjust but I still haven't figured it out yet trying a medium and large. Least comfortable on bridge of nose and intermittent leaks in several areas. I have tried with mask tight as well as loose as recommeded by the DME
Conclusion: Although the 407 had higher published leak rate, my results demonstrated that my leak rate was below the published data on this mask only.
Best AHI Results: 407
Questions:
1. Are we comparing apples to apples of published manufacturer leak rates at the same pressure?
In other words,the leak rate discrepancy on the manufacturer graphs between the Comfortgel (32) vs the F & P 407 (46.5) is significant at the same pressure (16cm H20)
2.If the published leak rate at 16 cm is 46.5, is it possible to have pressure at 15-20 for 2+hours?
I am a bit confused but starting to figure this all out . Thanks. This forum is incredibly helpful!!!!!

You have an APAP. The pressure is auto-adjusting (changing) throughout the night ... therfore the leak rate is also changing (leak rate is a function of the pressure). You are comparing averages of changing leak rates to averages of published leak rates ... there is no reason they should correlate with any significant accuracy.

If you want to do "observation & analysis" ... you need to get a copy of the software. The LED data from that machine is known to be less than accurate.

Dreamstalker,
Thanks for your input. The data I provided from my machine was via the Encore software. I download and evaluate daily.
I just was curious about the discrepancy in leak rates published by the manufacturer correlating with my data extracted from the software.
I guess I am looking for confirmation that yes indeed, the data from evenings using the F & P 407 are indeed superior than the other masks although this mask allows for a much higher leak rate. I guess I need to evaluate the entire picture with leaks, pressure changes and most importantly AHI results which apparently are best with the 407 mask. I am a bit surprised by the results but with more eveniongs of data, I will have a more realistic accounting of the results.

Yep. You need to maintain the same parameters for at least a week (ie. gather week's worth of data before changing masks, settings, etc.). Normal variations occur from night to night. You need about a week to capture all the variations (due to environmental and biophysiological factors) and then average all those variations.

The published leak rates I'm almost sure were done with NO variations at all ... with mask hooked up to contstant pressure machine and not a breathing human (pressure changes with each inhale and exhale and even then, each also vary thoughout the night). The published leak rates are meant to be used as a guideline for for accessing proper seal.

Remember, everyone's face is different. So every mask works different for each of us. As we move around at night in our sleep the shape of our face, the tugs on the hose, etc. all may affect mask leaks. You just have to find which one works best for YOU on an individual basis. Having the software helps speed that process along.

Good luck with your therapy.