5cm H20 CPAP
C.P.A.P. alters the pressure Gradient!
1cm H2O is equal to 0.735mm Hg.
7.5cm H2O CPAP increases the partial pressure of the alveolar air by approximately 1%.
This increase in partial pressure ‘forces’ more oxygen into the blood.
Even this comparatively small change is enough to make a clinical difference.