Continuing to document what I learn as I learn it....
When coming from zero knowledge and confronted by a bunch of graphs it's not immediately obvious what they all mean and how they can be used.
This explanation will hopefully remove the mystery for newbies (like me) trying to figure out what the machine is doing and why.
This description is specific to the
Resmed 10 Autoset because its behavior may be slightly different from some other machines.
Why does the pressure step upwards?
Because the machine thinks it detected one of three things (see the clinician's manual to verify that statement)
The device analyzes the state of the patient’s upper airway on a breath-by-breath basis and delivers
pressure within the allowed range according to the degree of obstruction. The AutoSet algorithm
adjusts treatment pressure as a function of three parameters: inspiratory flow limitation, snore, and
apnea.
So the machine will step up pressure if it sees any of the following..
a) An OBSTRUCTIVE apnea (clarified by @Bonjour below) ... not sure if it also responds to hypopneas.
b) Something "significant" changing in your flow limitations ( exact definition of "significant" is unknown to me but I have some suspicions)
c) Something "significant" changing with your snoring
Why does the pressure start to decrease?
Because the machine has not recently detected any of the three "Up pressure" conditions. (exact definition of "recently" unknown to me but you can guess by looking at graphs)
So how might you put this knowledge into practice?
1) Take a look at anybody's graphs and make sure that the machine is really a
Resmed S10 Autoset
2) You could look at my graphs for example if you don't have your own data
3) Look at the pressure curve and spot where it stepped "up"
4) Look at the events to see if an OBSTRUCTIVE apnea happened just before the step up
5) If you can't spot an "event"... then look to see if the "Flow limit" curve got noisy or spiky
6) If you can't spot that either... look to see if the "snoring" curve got noisy or spiky
7) You just figured out why the machine did what it did!
This is "obvious" for people who have figured it out.
Hopefully this post helps make it "obvious" for my fellow newbies.
Here's another spin on the same information
1) Look at my most recent graph (scroll up a bit or click here
http://www.apneaboard.com/forums/attachm...?aid=18122)
2) There's not many events... right?
3) So why is the pressure doing anything at all?
4) Now look at the "flow limits"
5) Also take a quick peek at the snoring
6) Conclusion... it's responding to the flow limits (when there are no events and no snoring)
This also helps to explain some of the reasons why the faq on organizing charts says which graphs to emphasize. (see my sig for that link)
The reason for hiding the calendar and the pie chart is so that people can easily see your settings without needing to ask or remember.
The reason for hiding the right side-bar is because it doesn't tell us anything.
For a similar easy to understand explanation of how to spot RERA/UARS related phenomena... click here..
http://www.apneaboard.com/forums/Thread-...#pid323859
