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Hi Folks,
Since my website http://www.1728.com is being referenced, I thought I'd mention that it does work perfectly. Specifically this calculator:
http://www.1728.com/convpres.htm
converts 20 cm of H2O to 0.28447 psi.

Some people have mentioned that cm of H2O was not a choice. Actually it is. On the button I showed it as a GmForce/sq cm.
Granted that is not the most common way to put it so, I just changed the calculator a little and now you can actually see that conversion option on one of the buttons.

That Davidson conversion website is quite good but (in my humble opinion) I like mine better because:
• It doesn't work by that "from" "to" method. Clicking one button yields all the conversions.
• It's faster and doesn't open another screen.

In deepest humility (LOL) I thank you for your attention.

wolf

the simplest form is a U tube manometer. It is indexed in centimeters (cm) instead of inches. PSI is Pounds Square Inch. These machines work in cm H20 as in a water tube manometer:

http://www.dwyer-inst.com/htdocs/pressu ... uction.cfm



you can make a simple U tube manometer, use a lath or yard stick and some 1/8" ID clear hose from the hardware store, round one end of the stick, wrap the clear hose around the edge of the stick, secure with shipping tape. Halfway down the stick put a -0- (zero) mark as shown above placing a mark above/below the -0- every 1cm. from 0 to 20cm. Fill the tube with water to the zero mark with eye dropper or syringe, connect one end of the hose to the oxygen port on your mask and turn on the machine, if machine is delivering accurate 10cm pressure it should push the water in the tube to 10cm mark as shown above.

Thank you to all who participated in this post.

I had quiet a few laughs this morning with my coffee and actually learned about the invention of CPAP.

I had never heard some of those units of pressure before. I am glad cm H2O is being used such an easy unit to test, no conversion needed. (Tubing and a ruler to test.)

I am glad CPAP is the course of treatment and not trics.

Now how many of you will use this new found knowledge and test your xPAPs on a regular basis.

WE ARE LUCKY TO HAVE THIS FORUM!!

Thanks Johnny...and to the rest of you.

My wife says her pressure changes worked perfect last night. The alarm woke her this morning. Interesting thing is I slept 6:34 and she slept 6:33, it takes awhile, but these machines are a huge help.

Thanks for the number Rested Gal...

1 cm H2O = .0142233 psi

20 cm H2O = .284 psi

dllfo wrote:My wife asked me exactly what does cm H2o mean? Can we compare it to Pounds per Square Inch (PSI) ?

I can read the words, but do not work with any other systems using it, so it is some nebulious term tossed out by an engineer with a propensity for accuracy.
It is a "relative term" to me, meaning...20 cm H2o is more than 10 cm H2o.

BUT is the scale linear or logarithmic?

Does 20 cm H2o roughly equal 20 PSI?

For those whose minds are clear and functioning within warranty specs, does it really matter for most of us?

Should it be construed as a simple scale for our use, not of any real importance to us?

Sometimes I like to "just know" what something means. Is there a simple explanation? BTW, one word answers don't get credit on today's exam

Take a tube, fill it with some water, bend into a "U" shape and blow enough pressure in one end to change the level of the water in the other end of the tube by 1 cm.

A web based conversion tool for you: http://www.convertunits.com/from/cmH2O/to/psi

Todzo wrote:... Take a tube, fill it with some water, bend into a "U" shape and blow enough pressure in one end to change the level of the water in the other end of the tube by 1 cm. ... A web based conversion tool for you: http://www.convertunits.com/from/cmH2O/to/psi ...

You know, it's shocking to realize that our xPAP devices deliver such a LOW pressure!! A wide open ASV unit might deliver 25cm H2O .. or just over about 1/3 of one PSI. !! ... That puts it into perspective, doesn't it? And it's another proof that even wide open an xPAP unit won't even be able to inflate a balloon.

JohnBFisher wrote:

Todzo wrote:... Take a tube, fill it with some water, bend into a "U" shape and blow enough pressure in one end to change the level of the water in the other end of the tube by 1 cm. ... A web based conversion tool for you: http://www.convertunits.com/from/cmH2O/to/psi ...

You know, it's shocking to realize that our xPAP devices deliver such a LOW pressure!! A wide open ASV unit might deliver 25cm H2O .. or just over about 1/3 of one PSI. !! ... That puts it into perspective, doesn't it? And it's another proof that even wide open an xPAP unit won't even be able to inflate a balloon.

It is kind of hard for me to believe that the pressure is high enough to push the obstruction aside. I think what happens is that the pressure in the airway is high and so the fluids run away from it effectively shrinking the tissues in the airway and so making more room.

I have often read that OSA is a disease of inflammation and I very much believe that is true. I think I will go and make some good "anti-inflammitory chili" today. Yup, a good day for anti-inflammitory chili.