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+--- Thread: relationship between flow limits, leaks and pressure (/Thread-relationship-between-flow-limits-leaks-and-pressure)
relationship between flow limits, leaks and pressure - TexasDon - 01-16-2024
I look first at the pressure graph and try to determine why the inhale pressure goes up/dwn. Sometimes I don't see any reason at all yet the inhale pressure goes up. But one thing for sure is that I see a correlation between flow limits and leaks. My nose says that the flow limits increase and the machine drives up pressure to overcome the restriction which in turn causes leaks at the higher pressure. That make sense?
Much thanks, Don
Resmed 10
Max 12, Min 8, EPR 3, swift fx mask
RE: relationship between flow limits, leaks and pressure - dataq1 - 01-17-2024
If your mask is leaking at "higher" pressures, you likely don't have a good seal to begin with. IMO, working on eliminating and or minimizing leaks is the very first order of business.
In the process of testing several FFM masks I seem to have found an interesting association, but I only have about a weeks worth of data to backup my tentative theory.
When the FFM mask I am testing has a significant time at large leaks (say greater than 15%), the flow limitation index is OK, but not great, say between 0.1 and 0.15.
However, when I eliminate large leaks (to say less than 1%), the flow limitation index increases significantly which causes the auto pressure to increase.
What I'm wondering is this: Does the existance of large leaks (>24l/min) degrade the Apap's ability to correctly evaluate flow limiitations?
RE: relationship between flow limits, leaks and pressure - SarcasticDave94 - 01-17-2024
Agreed in fix leaks first. See if FL reduce after low leaks, if not you'll need to edit pressure.
Leaks can be poor adjustment, poor fit, wrong size cushion. Number one mistake people make is getting them adjusted too tight.
Here's generically how to adjust the mask, holding mask in hand CPAP on, lying back hold mask in place and add finger tension until leaks are controlled. Remember how this feels and duplicate with the straps. To make leak monitoring simpler, don't go by the machine leak test, only by OSCAR charts. Bottom line though if the mask is uncomfortable or painfully tight to stop leaks, full stop. Change to another size or another model mask, even another form factor.
Suggestion is add OSCAR charts and let's see what you're dealing with. What kind of leaks are you facing? Mask or mouth leaks require different actions.
RE: relationship between flow limits, leaks and pressure - TexasDon - 01-17-2024
I am using a Resmed Swift mask ( nasal pillows ). On my 3rd headset maybe. I feel comfortable with the mask. Use clips to attach hose to my PJs for hose management.
I mouth tape ... wife demands it.
I experiment with adjusting. Honestly can't say if getting mask tighter or looser is better.
A bad night for me is an AHI of 1 or maybe 1.5. Typical is 0.2 to 0.8.
If I can solve the leak/flow limit/pressure issue I think I'll be soundly in the 0.2 AHI range. I think L/FL/P is the variable.
I have to reread how to get Oscar charts to show here.
Thanks!
RE: relationship between flow limits, leaks and pressure - TexasDon - 01-17-2024
Oscar screen shot ...
RE: relationship between flow limits, leaks and pressure - SarcasticDave94 - 01-17-2024
If I have it correctly, that first leak segment is the mask leak pattern. Jagged shaped leaks. Later, the wider, flatter leaks are more like mouth leaks in some way. It may also be mixed between both leak types.