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Measurements
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eseedhouse Offline

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Posts: 881
Joined: Dec 2014

Machine: ResMed Airsense 10 Autoset
Mask Type: Full face mask
Mask Make & Model: SimPlus
Humidifier: ResMed
CPAP Pressure: 7-10
CPAP Software: SleepyHead

Other Comments: Also on supplemental O2 at 3L/min. while sleeping.

Sex: Male
Location: Victoria, British Columbia

Post: #1
Measurements
The pressure units we use in CPAP are set in centimeters of water. I kinda wondered just what that meant. How does, say, 10cm from my APAP machine compare to the ambient atmospheric pressure we experience all the time.

1cm of water is the pressure required to raise the level of water in a tube by one centimeter. A manometer is of course just basically a tube full of water with lines on it.

Well, a hint on a Television program sent me to the web and some research and it turns out that 1cm of H2O is very close to one hectopascal in the "metric" system (actually S.I. system).

A hecotpascal is also very close to the meterological measurement of one millibar and the normal sea level air pressure is fairly close to 1000 millibars and thus to 1000 hectopascals as well.

So 1cm of water turns out to be about 1/1000 of the "normal" sea level pressure of our atmosphere.

If your hose blowing 10cm of pressure into your face feels fairly stiff (and it does to me) it is actually an increase of about 1% of standard sea level atmospheric pressure, which seems surprisingly small in that light.

I don't know the importance of this, but I found it interesting anyway...maybe some of you will too.

Ed Seedhouse
VA7SDH

I am neither a Doctor, nor any other kind of medical professional.

Actually you know, it is what it isn't.
06-01-2015 12:59 PM
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AshSF Offline

Advisory Members

Posts: 356
Joined: Oct 2014

Machine: PRS1 D560TS
Mask Type: Nasal pillows
Mask Make & Model: ResMed P10, Bkup: Airfit F10 & Quattro Air
Humidifier: PRS1 60 series with Heated Tube
CPAP Pressure: 8 - 8 w/ Aflex 3
CPAP Software: SleepyHead

Other Comments: Using APAP mode with fixed pressure

Sex: Male
Location:

Post: #2
RE: Measurements
FWIW, German measurements in CPAP world are all in mBars. Their sleep studies and their equipment all list pressure in mBars.

Since U.S. is not on metric system, cwp seems like a nice unit.

Started APAP 4-20, Closed range to 7.5-14, then straight 8.0 w/ Aflex 3
RDI always below 1. But sleep much much better at straight pressure.
Started on F10, Tried Quattro Air successfully. Finally settled on P10.
06-01-2015 02:58 PM
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under pressure Offline

Preferred Members-2

Posts: 139
Joined: Feb 2014

Machine: ResMed Airsense 10 Autoset
Mask Type: Full face mask
Mask Make & Model: F&P Simplus
Humidifier: Integrated
CPAP Pressure: 11 - 14
CPAP Software: ResScan SleepyHead

Other Comments: Also use F&P Icon Auto and Z1 Auto for travel and Backup

Sex: Male
Location: Colorado

Post: #3
RE: Measurements
(06-01-2015 02:58 PM)AshSF Wrote:  FWIW, German measurements in CPAP world are all in mBars. Their sleep studies and their equipment all list pressure in mBars.

Since U.S. is not on metric system, cwp seems like a nice unit.

Centimeters H2O is metric. Huh
(This post was last modified: 06-01-2015 03:55 PM by under pressure.)
06-01-2015 03:50 PM
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krelvin Offline

Advisory Members

Posts: 155
Joined: Jul 2014

Machine: Resmed S9 VPAP Auto BiLevel
Mask Type: Full face mask
Mask Make & Model: Quattro Air
Humidifier: S9 Series H5i Heated Humidifier with Climate Control
CPAP Pressure: 10.6cm - 18cm - PS 4cm
CPAP Software: ResScan SleepyHead

Other Comments: FlashAir WiFi SDcard with SleepMaster/FlashPAP - Weather Nut

Sex: Male
Location: Mesa AZ

Post: #4
RE: Measurements
New math... never know when it will get you.

Current Settings PS 4.0 over 10.6-18.0 (cmH2O) BiLevel Auto
TNET Sleep Resource Pages
CPAP Machine Database
06-01-2015 04:26 PM
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car54 Offline

Advisory Members

Posts: 110
Joined: Apr 2014

Machine: PRS1 Model 560P
Mask Type: Full face mask
Mask Make & Model: Airfit F10
Humidifier: PR system one
CPAP Pressure: 9-11
CPAP Software: SleepyHead

Other Comments:

Sex: Male
Location: Milwaukee, WI

Post: #5
RE: Measurements
Eseedhouse, thanks for the info. Interesting
06-01-2015 06:51 PM
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