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ow much pressure does a CPAP put out?
#1
Occasionally I see some threads from folks worried about a CPAP/APAP/BPAP/VPAP "blowing out their lungs". I was curious and farted around on the world wide internets for a while this morning. I found a converter tool and plugged in some various pressures in cm H20 and converted them to psi (pounds per square inch for the more metrically orientated):

06 cm H2O - 0.0853 psi
09 cm H2O - 0.1280 psi
12 cm H2O - 0.1707 psi
15 cm H2O - 0.2134 psi
18 cm H2O - 0.2560 psi
21 cm H2O - 0.2986 psi
24 cm H2O - 0.3414 psi

I also found a yootoob of a high school science class trying to determine the pressure at which a standard dime store latex balloon would inflate/explode. Their results showed that the balloon inflated at 810 mm Hg. It popped between 830-840 mm Hg - let's call it 835 mm Hg - more a measure of its upper stretchiness limit before the very thin latex would rupture.

810 mm Hg - 15.6628 psi
835 mm Hg - 16.1462 psi

So my lungs, when blowing up a balloon, would be subject to a pressure around 15 2/3 psi relative to the surrounding ambient atmospheric pressure.

So my APAP, at its maximum pressure setting of 15 cm H2O is pushing out roughly 1.36% of the pressure required to inflate a kid's balloon.

Note that most commercial jetliners have a pressure differential of around 7.5 - 8.5 psi to maintain around an 8,000 foot cabin pressure altitude cruising at say 35,000 feet MSL.

OMMOHY

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#2
I started a thread about this just two days ago--
Can you explain pressure measurement?

What we figured out in that thread is essentially the same as what you're saying in Post #1. The amount of pressure produced by a CPAP machine is really really small! 15cm of pressure is only about a 1-1/2% increase over ambient air pressure.
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#3
[Image: attachment.php?thumbnail=197]

Can a CPAP inflate a balloon ???
http://www.apneaboard.com/forums/Thread-...-a-balloon
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#4
Bookmarking this thread to pull out later when folks are freaking over the lung issue. With the links to the other threads in it and the numbers, it is perfect.
PaulaO2
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