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Curiosity - CA vs OA how are these different
#1
Curiosity - CA vs OA how are these different
Last night wasn't a particularly good night, although, not horrible either.  Occasionally, but not always, I notice as many as or more CAs than OAs.

Trying to understand them both a little better, I cloned a CA Flow Rate to compare to a similar duration OA Flow Rate.  I also cloned the Flow Limit for both events, with the intention of visually seeing them one on top of the other to discern what the difference is between the two.

Other than a small Flow Limitation around the CA, I cannot see a great difference between the two.

So it is more from curiosity and an interest to learn more that I am posting.  Is there a difference that my inexpert eye does not see?



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#2
RE: Curiosity - CA vs OA how are these different
I'll take a stab at it.

OA, Obstructive Apnea, is caused by a closed/obstructed airway.  CPAP treatment is to splint the airway open with a bit of air pressure.
CA, Central Apnea or Clear (not obstructed) Airway.  Central as in Central Nervous System. Basically no nerve signal is delivered to breath.  

Central Apnea
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#3
RE: Curiosity - CA vs OA how are these different
The difference between a CA and an OA is that an OA has some form of obstruction as measured by the machine. The machine sends a pulse wave of air into your lungs and measures the time for the echo to come back (a bit like a bat) but of a much lower frequency pulse. From this the machine makes a judgement on the amount of flow limitation (obstruction) and if there is some the event is scored as an OA if there is no Obstruction it is scored as a CA (Clear Airway).


Jason
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#4
RE: Curiosity - CA vs OA how are these different
I'm guessing that the OA is because of the large inhale after the event. The CA event has a small inhale afterward.
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#5
RE: Curiosity - CA vs OA how are these different
CA which typically shows up on Sleepyhead for example, can mean Clear Airway. That simply means your throat isn't collapsed/obstructed, but you're not breathing/breathing not registering via lack of flow.

For Central Apnea, it's where pressure induced via xPap therapy can confuse the brain into not triggering a breath. It's cause can be due to an imbalance between oxygen and carbon dioxide expected levels. There's other possible causes, but I've forgotten exactly the proper descriptions.

In myself, I know that mine were pressure induced. So the theory that was to help was actually causing new symptoms. My solution was the ASV machine. And it has worked wonders. My BiPAP PSG showed 124 Central events. Now with ASV, over the past month AHI is 0.4.

Dave B. Coffee
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#6
RE: Curiosity - CA vs OA how are these different
I have the same question(s) as Cpapian.....

To rephrase the question(s), as I understand it:

Look closely at the chart. CA and OA events can look very similar on a SleepyHead chart.
How does an OA look different from a CA on a sleep chart? Since the waves are similar, how does the machine distinguish a CA from an OA? According to the chart, what is the body doing during the CA vs. the OA that meets the definition of each kind of apnea?
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#7
RE: Curiosity - CA vs OA how are these different
(11-08-2017, 03:36 PM)HalfAsleep Wrote: I have the same question(s) as Cpapian.....

To rephrase the question(s), as I understand it:

Look closely at the chart. CA and OA events can look very similar on a SleepyHead chart.
How does an OA look different from a CA on a sleep chart? Since the waves are similar, how does the machine distinguish a CA from an OA? According to the chart, what is the body doing during the CA vs. the OA that meets the definition of each kind of apnea?

I'm a newb but I think I know the answer to this one.  When you are having the apnea event the machine sends a pressure pulse to test your airway.  If the pulse is blocked by an obstruction in your airway it knows the event is obstructive apnea.  If the pulse flows freely into your lungs then it classifies it as a clear airway / central apnea event.
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#8
RE: Curiosity - CA vs OA how are these different
OK sorry, I had drifted away from the question by just defining OSA and CSA. The chart used shows obstructive as having a greater positive then passing zero into the negative side. It has a somewhat sharp negative peek at it's extreme, followed by it's return towards positive. The CA doesn't go positive or negative as far, are more rounded instead of sharpened peaks and also seems to increase in it's swing a bit then tapers back off.

Let me try adding one of my BiPAP ones on for comparison:

OK sorry. I can't find the BiPAP images that would have helped. If I can find one, I'll add it later in another post.
Dave

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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEBSITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#9
RE: Curiosity - CA vs OA how are these different
lets get your min pressure up to 10 and help with events before they even get started. I'd also raise the max to 15 and give some head space.
next is to fix what I think could be mouth breathing, from your tidal volume of 320. Do all the stuff they discuss and get some charts up. If that doesn't work to get up around, for an average build 500 with a good chart, get a FFM


edit, Just noticed you are a female, 320 can be ok of you are short and small framed. it would need to look at the charts to see if there are indicators



what I'm seeing is a few deep breaths after the OA and a slow return to normal after the CA. both are typical for oa and ca
Some CA are/can be just your body regulating your o2/co2 balance as a new cpap users and will settle within 12 weeks.
mask fit http://www.apneaboard.com/wiki/index.php...ask_Primer
For auto-cpap, from machine data or software. You can set the min pressure 1 or 2cm below 95%. Or clinicians commonly use the maximum or 95% pressure for fixed pressure CPAP, this can also be used for min pressure.
https://aasm.org/resources/practiceparam...rating.pdf
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#10
RE: Curiosity - CA vs OA how are these different
(11-08-2017, 03:43 PM)FunkOdyssey Wrote: I'm a newb but I think I know the answer to this one.  When you are having the apnea event the machine sends a pressure pulse to test your airway.  If the pulse is blocked by an obstruction in your airway it knows the event is obstructive apnea.  If the pulse flows freely into your lungs then it classifies it as a clear airway / central apnea event.

But.....it’s often the case that there is no flow limit (see the flow limit chart)—so no obstruction is being picked up—but the events are still evaluated as OAs.

At least half my events labeled OA have no contemporaneous flow limit.

I have exactly the same questions as Cpapier, and I don’t want to hog this thread.
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