The formula to calculate the Fio2/Pao2 ratio (R) is:
\[ R = \frac{P}{F} \]
Where:
Let's say the partial pressure of oxygen in arterial blood (Pao2) is 80 mmHg and the fraction of inspired oxygen (Fio2) is 0.21. Using the formula:
\[ R = \frac{80}{0.21} \]
We get:
\[ R \approx 380.95 \]
So, the Fio2/Pao2 ratio is approximately 380.95.