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Why is CPAP capped at 20cm?
#1
Why is CPAP capped at 20cm?
I have a Dreamstation Auto BIPAP and on the CPAP setting the highest you can go is 20cm. Yet you can go to 25cm using BIPAP or Auto BIPAP. Any clues to why they do that?
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#2
RE: Why is CPAP capped at 20cm?
Total guess on my part, but I would think that damn few people can exhale comfortably at pressures over 20 cm h20
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#3
RE: Why is CPAP capped at 20cm?
It may be due to the current practice which is, if a person needs a higher pressure, a bilevel is prescribed due to the difficulty adapting to exhale at the higher pressure. Pretty much the same as TASmart. Just my opinin.

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#4
RE: Why is CPAP capped at 20cm?
(08-02-2017, 11:49 AM)TASmart Wrote: Total guess on my part, but I would think that damn few people can exhale comfortably at pressures over 20 cm h20

I guess I am Damn few people.    Big Grin  I-love-CPAP
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#5
RE: Why is CPAP capped at 20cm?
Bonjour, you are a special case in, oh, so many ways...
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#6
RE: Why is CPAP capped at 20cm?
As I read the OP, he has a BiPAP. In CPAP mode, it can only be set to 20 cm-water. He asks why the limit if the machine can achieve 25 in BiPAP mode.
I do not know why.

SWAG:
It may be that a continuous pressure greater than 20 cm-water may interfere with the hemodynamics of the right side of the heart.
The right side ventricle works at about 25 mm-Hg pressure. 20 cm-water is about 15 mm-Hg. Increased load on the right side might result in pulmonary hypertension and/or right side heart failure. I cannot prove this. The exercise is left to the reader to find references.
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#7
RE: Why is CPAP capped at 20cm?
You would think If that were the case that BIPAP's would be capped at 20cm also. But I don't know, that's why I asked.  Dont-know
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#8
RE: Why is CPAP capped at 20cm?
Why 20cm? I don't know why 20. As you noted CPAP mode is limited to 20. I'm sure that this is to mimic CPAPs. I suspect that the blower for BiPap/BiLevel is more expensive and allows a 2nd tier for those that need it.
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#9
RE: Why is CPAP capped at 20cm?
The failure mode pressure for these blowers, if they go open loop, is about 40 cm-water.
It's time limited, should fault and shutdown.
I read that in some ResMed specification.
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#10
RE: Why is CPAP capped at 20cm?
My guess:
A bilevel is to provide pressure support. Unless PS > 4, you stick with a cpap with epr. So IPAP is the one that typically goes up to 25.

I think it's pretty rare to go to an EPAP over 20. Thus a cpap only goes till 20.
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