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How Does CPAP Machine Work?
#1
I am really curious how the CPAP machines work internally. I have a ResMed S9 Elite. I have looked on the Internet and could not find any info. Thanks, Bob.
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#2
If you want to have fun, buy an old used one from Craigslist and take it apart.

Inside are probably 1 - 2 boards with electronics. One will have the firmware that keeps track of everything. Then there'd be the air pump itself.
PaulaO2
Apnea Board Moderator
www.ApneaBoard.com


Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.




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#3
Thanks. I am not that interested in paying for one. I was hoping someone could describe what was inside or find a website with detailed information. Regards, Bob.
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#4
there are some pictures here
http://www.apneaboard.com/forums/Thread-...AP-machine
http://www.apneaboard.com/forums/Thread-...h-old-CPAP
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#5
CPAP machines are basically reversed vacuum cleaners. I'm pretty sure that the first one made by Dr. Sullivan was exactly that: a vacuum cleaner that was tinkered with.

Generally the same concepts apply. The difference is that CPAP machines have better parts than vacuum cleaners, plus some technology to control the flow rate and a few other handy adjustments.

That's the extent of my internal CPAP wisdom. Sorry... it ain't much. Bigwink

Truth is that CPAP manufacturers are pretty secretive concerning their equipment, especially the firmware and algorithms that they use. You're not going to find anywhere out on the Net where the proprietary insides of CPAP machines are revealed and explained in detail.
SuperSleeper
Apnea Board Administrator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.



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#6
Prettified leaf blower!
PaulaO2
Apnea Board Moderator
www.ApneaBoard.com


Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.




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#7
Bob
I will try to add a little bit to the discussion. This is more more how I think it works than information from cpap suppliers etc. so feel free to comment.
Where I live atmospheric pressure is about 14.7 lb/sq in. This is equal to the pressure exerted by a column of water about 33.9 feet or about 1035 centimeters high. Cpap pressure is measured in gage or relative pressure which is how much higher or lower the pressure is compared to atmospheric pressure which is defined as Zero gage pressure. If my cpap pressure is 10 centimeters it would also be 1045 centimeters absolute pressure. It does not seem like much increase. If I breath in without cpap my lungs expand dropping my lung and airway pressure below atmospheric pressure. Since the pressure outside (atmospheric - Zero) is higher than my lung and airway (negative) pressure air flows from outside thru the airway to my lungs. (Air is pushed not pulled) The negative airway pressure which is required to inhale without cpap contributes to apnea for many people. My cpap machine provides me a new atmosphere (in the mask) at a (positive) higher pressure than the pressure outside the mask.
When I breath in with cpap my lungs still expand and the pressure drops below my new atmosphere so air will flow in but my lung pressure is positive when I start to breath in and if the cpap pressure is set high enough my lung and airway pressure remain positive throughout the breathing cycle. That is the purpose of cpap.

The cpap machine works in conjunction with the tubing and mask to control pressure. The mask has an exhilation port or orifice to control the flow of air from the circuit. The higher the pressure in the mask the more air flow from the mask. There is usually a pressure/flow chart furnished with the mask. The cpap machine has at a minimum a pressure sensor, flow sensor, and clock. These sensors send data to the cpap control circuit. If the pressure sensor detects low pressure, low flow, or whatever, more voltage is applied to the DC Motor and the machine speeds up and increases air flow to the tubing and mask. In order to exhaust the increased rate and volume of air flow the pressure in the mask increases. The machine keeps sensing pressure and varies the flow rate until the desired pressure is achieved at the machine. Since the important pressure is the pressure at the mask and not at the machine the machine is programmed to compensate for the pressure loss between the machine and the mask.

I hope that this is helpful and not just confusing.
GeneS



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#8
Hi Gene. GREAT! Thanks for all the information. I appreciate it. Regards Bob.
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#9
Nicely done, genes. Well-done
Sleepster
Apnea Board Moderator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#10
Yep, much better explanation than my 'reverse vacuum cleaner' story. Coffee

Thanks Genes! Smile
SuperSleeper
Apnea Board Administrator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.



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