Post Reply 
Inhaling exhaled CO2 gases
Author Message
bryank1 Offline

Preferred Members

Posts: 53
Joined: Oct 2012

Machine: Resmed S9 autoset CPAP
Mask Type: Full face mask
Mask Make & Model: Quattro FX
Humidifier: Resmed HSi
CPAP Pressure: 9-15
CPAP Software: SleepyHead

Other Comments: Wrist oximeter: CMS50IW

Sex: Male
Location: Washington State

Post: #11
RE: Inhaling exhaled CO2 gases
(11-22-2012 10:31 PM)archangle Wrote:  You don't have to worry about rebreathing CO2 as long as you're using standard CPAP equipment in proper working order.

First, realize that you exhale Carbon Dioxide, CO2, not Carbon Monoxide, CO. Carbon MONoxide is the stuff that kills you if you have a car exhaust leak. A fair number of people confuse the two. There is no Carbon Monoxide involved in CPAP. (Except whatever pollution is in the air you breathe even without CPAP.)

Long before CPAP was thought of, we figured out the hazards of rebreathing CO2 from using ventilators. The physics of the situation are very well understood, safe levels were established, and CPAP equipment was designed to have a large safety margin.

The minimum pressure most machines will produce is 4 cmH2O. The exhaust holes are designed such that they leak out enough air at that pressure that they will clear out the exhaled air enough to prevent the build up of CO2 and depletion of O2 to harmful levels. Unless the exhaust air holes are plugged, or the machine is producing less than 4 cmH2O, you won't get enough rebreathing to be harmful.

By the way, the hazard to rebreathing air is not so much from high CO2, as it is from low O2.

Also, the effect of rebreathing some of your exhaled air is much the same as having apnea. In either case, O2 has a hard time getting into your lungs and CO2 has a hard time getting out.

Enough for one post. Time to stop to let my keyboard breathe for a bit.

Thanks Arch, I did mean carbon dioxide. my bad.
11-22-2012 11:14 PM
Find all posts by this user Post Reply Quote this message in a reply

Donate to Apnea Board
archangle Offline
Wiki Editor
Advisory Members

Posts: 3,159
Joined: Feb 2012

Machine: ResMed S9 AutoSet
Mask Type: Nasal pillows
Mask Make & Model: ResMed Swift FX
Humidifier: ResMed S9 H5i
CPAP Pressure: 16-20
CPAP Software: ResScan SleepyHead EncoreBasic

Other Comments: Happy PAPper

Sex: Undisclosed
Location: USA

Post: #12
RE: Inhaling exhaled CO2 gases
(11-22-2012 11:14 PM)bryank1 Wrote:  Thanks Arch, I did mean carbon dioxide. my bad.

No, you didn't mention "monoxide." I did, just because you wouldn't be the first to confuse the two.

Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
11-22-2012 11:55 PM
Find all posts by this user Post Reply Quote this message in a reply
Post Reply 


Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  [CPAP] ResMed AirSense 10 makes loud noise when inhaling. sanger 86 30,029 11-17-2016 09:14 PM
Last Post: comphelp
Gross [Equipment] Resmed S9 fan noise when inhaling Hley1 3 602 07-14-2016 01:32 PM
Last Post: PaulaO2
  noise when inhaling papaw 4 1,202 11-25-2015 10:29 AM
Last Post: AshSF
  breathing in too much exhaled air Visitor 13 3,309 06-11-2014 04:54 PM
Last Post: zonk
  [CPAP] CPAP noise when inhaling paintermac 12 14,409 03-02-2014 06:26 PM
Last Post: DeepBreathing

Forum Jump:

Who's Online (Complete List)