palerider wrote:archangle wrote:Atmospheric pressure is around 1000 cmH20. Max CPAP pressure is around 20 cmH2O.
your casual throwing around of approximation of facts creates chaos.
one atmosphere of pressure = 1033.23 cm/h2o
absolute which means *nothing*.
max cpap pressure from commercially available home machines is 30cm/h2o
*ABOVE AMBIENT PRESSURE" which *stares pointedly at "guest"* that the maximum pressure in a resmed bilevel cpap would be 1066.23
compared to a total vacuum (0 pressure).
none of that matters, because cpap pressure is related to the ambient pressure around the machine. 5, 10, 20, 30 cm/h2o
*ABOVE AMBIENT*
Sorry. I'll try to type more slowly this time so you can understand.
If you take air at normal atmospheric pressure of around 1000 cmH2O absolute and add the maximum 20 cmH2O gauge pressure that CPAP machines do, you increase the pressure of the air you're breathing to around 1020 cmH2O absolute. PV=nRT. P is measured in absolute pressure.
This amounts to about a 2% increase in the concentration of CO in terms of grams per cubic meter and the eventual CO concentration in your blood.
If, for instance, your room air was at the 1,600 ppm "dead in two hours" CO concentration, the CPAP user would be receiving the equivalent of 1632 ppm CO concentration. It's probably not really going to make much of a difference. Maybe the CPAP user would be dead in 117 minutes instead of 120 minutes. (Of course, the 2 hour number isn't that precise anyway.)
If it's a bilevel machine set at 30 cmH2O, it might be 116 minutes instead of 120 minutes.