2 masks--2 different sets of data

For the past 2 months I have been alternating between my old faithful Quattro FX full face mask and the FitLife total face mask. I have noticed that, while using the QFX, my Patient Triggered Breaths are lower and Tidal Volume is lower than when I use the FitLife. For example, %PTBs with QFX - 30's to 70's, %PTBs with FitLife - 90's. TV with QFX - low 400's, TV with FitLife - mid 500's. This has consistently played out over the past 2 months and I have no ideas why this is happening. Oh yeah, AHI and sleep quality are both about the same with both masks, and leaks are minimal with both masks as well.

Anyone have a theory about this difference in data regarding the 2 different masks? I know the results are better with the FitLife, but I don't want to give up my QFX.

Theory only!!!!

Looking at the pictures of these masks, what strikes me is the difference in the distance between the upper and lower headgear straps. The FitLife distance is much larger. It may be that the Quattro, because it is shorter, pulls back on the lower jaw to a greater extent than the FitLife does.

My experience with the Oracle 452 mask and chin straps, is that this can move the jaw slightly backwards and increase the tendency to have additional obstructive events. If the same thing is happening with the Quattro, then your ASV machine, which seems to be more sensitive to such things, is reacting and triggering the ventilator mode more often.

Have you tried making the lower strap on the Quattro just slightly looser without increasing the leak rate?

This is just speculation based on looking at the user manuals for each mask and something else might very well be going on.

This issue comes up from time to time -- no clear, coherent answer. Numbers often change based on mask brand and type. Lower AHIs on FFMs or Pillows or Nasal or vice versa.

Why? Unknown, although I am sure there are some engineers at PR and ResMed who know why this takes place -- it's either the fit on the patient's head and how the patient positions himself while sleeping, or how the headgear and jaw, etc. interact, -- or, basically, is just evidence of the imperfect nature of the machines themselves, that they will produce differing numbers simply based on the mask volume and venting, etc.

So pick a mask, stick with it, and see what numbers look good, or if you want to switch masks night to night, then just don't sweat the data so much, as long as you don't have leaks. You can really only do so much, and the machine has to do the rest.

JDS74 wrote:Theory only!!!!

Looking at the pictures of these masks, what strikes me is the difference in the distance between the upper and lower headgear straps. The FitLife distance is much larger. It may be that the Quattro, because it is shorter, pulls back on the lower jaw to a greater extent than the FitLife does.

My experience with the Oracle 452 mask and chin straps, is that this can move the jaw slightly backwards and increase the tendency to have additional obstructive events. If the same thing is happening with the Quattro, then your ASV machine, which seems to be more sensitive to such things, is reacting and triggering the ventilator mode more often.

Have you tried making the lower strap on the Quattro just slightly looser without increasing the leak rate?

This is just speculation based on looking at the user manuals for each mask and something else might very well be going on.

Thanks for the I put, JDS. Right now I have the lower straps on both masks just barely snug enough to prevent leaks, not too tight. I like your theory of jaw position/ASV sensitivity; it makes sense. I sleep with a next roll tucked under my chin to prevent tucking my chin under and jaw drop. It works well enough, but I may still end up with a backwards jaw while sleeping.

I questioned whether or not it might have something to do with the air space in the mask itself, which is something I know absolutely nothing about.

hyperlexis wrote:This issue comes up from time to time -- no clear, coherent answer. Numbers often change based on mask brand and type. Lower AHIs on FFMs or Pillows or Nasal or vice versa.

Why? Unknown, although I am sure there are some engineers at PR and ResMed who know why this takes place -- it's either the fit on the patient's head and how the patient positions himself while sleeping, or how the headgear and jaw, etc. interact, -- or, basically, is just evidence of the imperfect nature of the machines themselves, that they will produce differing numbers simply based on the mask volume and venting, etc.

So pick a mask, stick with it, and see what numbers look good, or if you want to switch masks night to night, then just don't sweat the data so much, as long as you don't have leaks. You can really only do so much, and the machine has to do the rest.

I know you're right, hyperlexis. I wear my QFX 6 nights a week, and on Saturday night I wear the FitLife to keep strap marks from my pillow off my face and neck during early church Sunday morning! The FitLife extends to the edges of my face, so no straps beyond the hairline. Such is my vanity.

Overall my numbers are good, so no complaints. I was just curious. Thanks for your reassuring imput!

M'ohms wrote:... I questioned whether or not it might have something to do with the air space in the mask itself, which is something I know absolutely nothing about.

The FitLife small has 50% more dead space than the Quattro but they both have the same intentional leak rate of about 60 Lpm at 25 cmH20. Even so, that would result in only a tiny difference in CO2 clearance between the two masks; 60,000 cc of air flushing 350 or 242 cc of dead space. That can't be enough difference to matter.

Your original question remains interesting

M'ohms wrote:Anyone have a theory about this difference in data regarding the 2 different masks?

Purge characteristics. Quattro is flushier:

Threadkiller strikes again...

Morbius wrote:Threadkiller strikes again...

In addition to the air venting from the elbow itself on the FitLife, there are also holes on the mask next to the elbow (sort of like the F10, only fewer and larger). I agree that the QFX is flushier.

OK, busy watching for the Revealing of the Easel, but Flushier = More CO2 Washout and explain the difference in breathing pattern.

Morbius wrote:OK, busy watching for the Revealing of the Easel, but Flushier = More CO2 Washout and explain the difference in breathing pattern.

This is where my eyes glaze over. I have read about this any number of times, but I don't understand it. Can you explain this principle to this thick-skulled ninny?

M'ohms wrote:

Morbius wrote:OK, busy watching for the Revealing of the Easel, but Flushier = More CO2 Washout and explain the difference in breathing pattern.

This is where my eyes glaze over. I have read about this any number of times, but I don't understand it. Can you explain this principle to this thick-skulled ninny?

Sure.

A framed notice of birth will go on display on a ceremonial easel on the forecourt of Buckingham Palace. So far it's just the birth.

Anything from Buckingham Palace makes my eyes glaze over.

M'ohms wrote:Anything from Buckingham Palace makes my eyes glaze over.

Well, after Nepal, Everest, Baltimore, and for cryin' out loud a 29 year old father falling into the Grand Canyon (and needless to say...), I'd like to hear a little good news.

Morbius wrote:

M'ohms wrote:

Morbius wrote:OK, busy watching for the Revealing of the Easel, but Flushier = More CO2 Washout and explain the difference in breathing pattern.

This is where my eyes glaze over. I have read about this any number of times, but I don't understand it. Can you explain this principle to this thick-skulled ninny?

Sure.

A framed notice of birth will go on display on a ceremonial easel on the forecourt of Buckingham Palace. So far it's just the birth.

It's a girl and she pushed her poor uncle another notch down the totem pole already.