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[Pressure] Events vs Pressure
#1
Events vs Pressure
Hi folks.  I'm new to al of this and still trying to understand how to interpret my data.  Per the attached pic, I've highlighted to events close together where I clearly experienced an obstructive event of 15 seconds but the machine appears not to have responded at all.  The pressure seems basically flatlined through the events.  What gives?


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#2
RE: Events vs Pressure
ResMeds (and other brands) respond to more than just Apneas. They respond to Flow Limitations (FLs), Snores and Apneas. IMO, FLs are probably the largest indicator of a need to respond, and Apnea's are often not responded to, during an even but after an event.

In the picture you presented you see the pressure actually increasing before the device has actually determined an Obstructive Apnea(OA) occurred. It was likely responding to FLs. In the second event, one again it started the presure increase prior to determining an OA occured, but still increased it after.

I don't see anything strange about how your device responded.
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#3
RE: Events vs Pressure
(06-07-2022, 09:38 AM)Dog Slobber Wrote: ResMeds (and other brands) respond to more than just Apneas. They respond to Flow Limitations (FLs), Snores and Apneas. IMO, FLs are probably the largest indicator of a need to respond, and Apnea's are often not responded to, during an even but after an event.

In the picture you presented you see the pressure actually increasing before the device has actually determined an Obstructive Apnea(OA) occurred. It was likely responding to FLs. In the second event, one again it started the presure increase prior to determining an OA occured, but still increased it after.

I don't see anything strange about how your device responded.

Ok thanks very much for that insight
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#4
RE: Events vs Pressure
It would be much easier to see what is happening if you put up the entire night of OSCAR ( totally free at the top of the site)
Apnea (80-100%) 10 seconds, Hypopnea (50-80%) 10 seconds, Flow Limits (0-50%) not timed  Cervical Collar - Dealing w DME - Chart Organizing
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#5
RE: Events vs Pressure
If you look at this picture you will notice that that during that first apnea (starts at the green line) the pressure is actually on a downwards trend BUT if you look at the pressure and look at the respiratory rate the pressure starts going up when the respiratory rate drops (the blue lines). 

If you then look at the second image with just the blue line you will see that the apnea actually occurred after the flow rate started back up again, basically brain going "oh whoops dozed of there for a second almost but not quite creating a central apnea, let me just breath harder and faster to try to catch back up" at which point trying to force the air through quicker caused the mussels to tighten up thus contracting the airway and created the obstructive apnea by trying to prevent a central apnea. The machine responded to the reduced breathing rate increasing the pressure but then didn't increase the pressure when the obstructive apnea started because it had already preemptively reacted when the breathing rate reduced before the actual apnea.

With you only including the two things of data and not other important data that graph looks perfectly normal because the machine takes into more then just "apnea or not" when deciding to increase or decrease the pressure. If you are struggling to breath because you can not exhale properly it doesn't make sense to increase the pressure making it harder to exhale, if you are struggling to breath because you can't inhale then that is when it makes sense to increase the pressure. 

As such I would be willing to bet you a nickel that if you compare the pressure to your inhalation and exhalation graphs that the pressure graph would almost certainly line up more with increasing pressure if your inhalations are taking longer than your exhales and decrease the pressure if your exhalations are taking longer than your inhales like the way the third image shows, and I am not a betting man.

EDIT: Looking at about a week or random days that does seem to be the common theme among when the pressure goes up and down, when the inhalation rate is greater than a 1.5:1 ratio to exhalation the pressure goes up, when the inhalation rate is less than a 1.5:1 ratio to exhalation the pressure goes down. (+/- a few percent to the ratio where it stays flat if it is close enough to that 1.5:1 ratio)... Obviously there are other factors, but between a random set of different days ranging from 3 AHI to 18 AHI that seems to be the most common denominator as to when the machine decides to do what is the inhalation to exhalation ratio.


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