manometer reading?

should the manometer reading be taken at the mask?/ the reason i ask is that different masks have differ leak rates--but i assume the machine puts out a certain volume of air at a certain pressure---does the m series change its volume of air on each mask--with all the different leak rates---i seem to have different ahi#'s in encore pro ---with different masks---but the leak rates are all acceptable in the software,,,no major leaks with different masks---i am totally confused--that if i change mask and have no leaks that my ahi goes up---it should not --provided i'm getting the same volume and pressure---am i nuts or what?

The machine is designed to achieve a set pressure. Its variable speed pump increases volume as required to reach the set pressure in spite of leaks up to the point where the machine can't go any faster and the leak wins. The large leak notation indicates the machine can't keep up.

My AHIs stay around 1.7 regardless of the mask I use unless I switch to APAP and then it goes up slightly over 2 because the apnea happens before the machine boosts pressure to break the apnea. If I set the low end high enough to prevent the apnea (my CPAP setting) I don't get any benefit from APAP.

I wouldn't expect just the mask and leak rate change to cause an AHI raise.

TerryB

sleepie40 wrote:should the manometer reading be taken at the mask?/ the reason i ask is that different masks have differ leak rates--but i assume the machine puts out a certain volume of air at a certain pressure---does the m series change its volume of air on each mask--with all the different leak rates---i seem to have different ahi#'s in encore pro ---with different masks---but the leak rates are all acceptable in the software,,,no major leaks with different masks---i am totally confused--that if i change mask and have no leaks that my ahi goes up---it should not --provided i'm getting the same volume and pressure---am i nuts or what?

sleepie40,

Manometers, typically, are used to verify pressures close to the output of the device generating the flow. With xPAP units that measurement is typically taken at the hose-end where the mask attaches.

Too, it depends on which manometer is used and its design or accompanying fittings and adapters as to where you can attach it. Most of them in after-market that I've seen that are made for xPAP measurements attach at the end of the hose where the mask would attach. Several RT's I've met have used adapters to attach their manometer directly to the output flow port of the xPAP. Others have attached their manometer to the hose end.

With each mask having a its own designed-in vent rate, which is actually a method of avoiding carbon dioxide saturation from rebreathing moderate to large portions of exhale on an inhale portion of the breathing cycle. Even many nasal interface masks now have designed-in vent, i.e. the OptiLife by Respironics. The rate of designed vent is pressure-dependant, varying higher with higher pressure and flow output by the flow generator.

The AHI's can vary for many reasons from mask to mask and pressure settings to pressure settings with each different mask. Much is person-dependant and their particular physiology and their brain-set. There I mean how a person's brain is adapted/set to perceive and react to physiological conditions in conjunction with what their particular current physiology can accomplish or handle on command from the brain.

Less to zero mask leak causing higher AHI's with certain masks could be an indication that the machine pressures need to be adjusted, most likely raised slowly in small steps to counter/prevent the events that AHI numbers are based on. That can take weeks to figure out if it's going to work at a changed pressure setting, as the body and brain have to adapt. Too, but it could be that the brain needs more time to adapt to the situation in order for it to do its best at controlling the physiology, as best it can, in the breathing ductwork. The brain can quickly react or adapt, but locking in the changes into the brain to where they become the norm takes some time in most people. Too, muscles, muscle groups and even body cells have “memory” and “memory effects.”

For instance, all with the same mask, I've done really well at say 9cm H2O for months, and then that 9cm H2O doesn't seem to be working as well regardless of what I try. A change to 10cm H2O then was great at lowering my AHI's, or sustaining them level for months. Then 11cm was necessary to sustain or lower AHI levels. Any change I make I try to give four to six weeks or longer to in order for the physiology and brain to become fully adapted to it. That is, unless a change is obviously causing a repeated problem -- the problem severity dictates how quickly I back-step or alter anything.

Breathing being a base vital to sustain life, the brain doesn't like large changes, or many changes in rapid succession, if the brain perceives them as out-of-channel or off its acceptable scale of comfort and routine of interaction with the physiology.

NOTE: I am not a doctor and have no medical degrees. My comments are based in years of intense study and personal research in published medical texts and clinical and case studies, and spiced with some common sense.

Maybe after my 4th cup of coffee I'll be able to relate some of it better.

Nodzy

thanks for the ans to my problem---why i ask this question is ---this--i use a ultramirage nasel mask for about 8 months--i worked my pressure to 12-13.5 on my mseries auto----during this time and ajustments i got consistant ahi below 1----with all the talk of mouth breathing,and i know it happens to me sometimes--i thought to try a full face mask--about 3 months ago i did this for 2 nights--my ahi the first night went to 5.6--the second night was 6.2---so i quit this----but as time went on ,,i had the oppurtunity to try another full face mask-different manufactorer--this time ahi went to 7.9--i had no leaks,,so i was trying to figure it out---thinking maybe it was a pressure thing---on this particular night the machine stayed 13.5 most of the night fighting apneas--changed back to my nasel and the next night i'm back down to .8--nodzy if i read you right --then i should ajust my pressure up, alittle at a time,,,when trying the full face mask----thanks for all your help--all of you are fantastic----pat

sleepie40,

In answer to your last post, you may even have to go down a bit on pressure. I didn't realize you were already above 11cm H2O on pressure. I just know from my experience that different masks require me to sometimes change pressures to get better, the lowest possible, AHI's. But, as long as I'm in the 2.5 or lower range overall.... I'm comfortable that the therapy is working well. Though, I'll never heal completely, I can sure tell a difference between great therapy and barely adequate therapy when I wake and start moving around.

Good luck, and don't be afraid to slowly make changes in attempt to find what works best for you -- as this therapy has to be a custom fit to each user with respect to the functioning of the machine and mask they use.

Nodzy