Final answer:
The desired FiO2-PaO2 equation is used to calculate the partial pressure of oxygen in the alveolar spaces within the lungs. It takes into account the respiratory quotient (RQ) and the partial pressure of carbon dioxide (PCO2) in the alveoli.
Step-by-step explanation:
The desired FiO2-PaO2 equation is used to calculate the partial pressure of oxygen in the alveolar spaces within the lungs. It takes into account the respiratory quotient (RQ) and the partial pressure of carbon dioxide (PCO2) in the alveoli.
The equation is: FiO2 = (PaO2 + [PCO2/RQ]) / (Pb - [PH2O x FiO2]), where FiO2 is the fraction of inspired oxygen, PaO2 is the partial pressure of oxygen in the alveoli, PCO2 is the partial pressure of carbon dioxide in the alveoli, RQ is the respiratory quotient, Pb is the barometric pressure, and PH2O is the vapor pressure of water.