[indian]

How come PACO2 does not affect PAO2?
If this is true then why we should avoid giving Oxygen to COPD patients?
I understand that giving O2 to these patients will further exacerbate their hypercapnea, am I right?

 

[StepTaker]

The equation is
Alveolar O2 Pressure = Inspired O2 Pressure - Alveolar CO2 Pressure/R

from this equation obviously any change in alveolar PCO2 will change the PAO2.

But the reverse is not true and the worsening hypercapnea in oxygenated COPD patients is seen because of you'll remove the only reason they breathe [which is hypoxia] and so you induce hypoventilation

 

[indian]

and by the way
any change in the factors that affect alveolar CO2 will ultimately change O2
for example ventilation and metabolic rate