The formula to calculate the PaO2/FiO2 ratio is:
\[ \text{Ratio} = \frac{\text{PaO2}}{\text{FiO2}} \]
where \( \text{Ratio} \) is the PaO2/FiO2 ratio, \( \text{PaO2} \) is the partial pressure of oxygen in arterial blood (mmHg), and \( \text{FiO2} \) is the fraction of inspired oxygen (decimal).
The PaO2/FiO2 ratio, also known as the P/F ratio, is a calculation used in medicine to assess the severity of hypoxemia, or low blood oxygen levels, in individuals with respiratory conditions such as acute respiratory distress syndrome (ARDS) or pneumonia. It is calculated by dividing the partial pressure of oxygen in arterial blood (PaO2) by the fraction of inspired oxygen (FiO2). A normal P/F ratio is typically above 300, and a lower ratio indicates a greater severity of hypoxemia.
Let's assume we have the following values:
Step 1: Divide the partial pressure of oxygen by the fraction of inspired oxygen:
\[ \text{Ratio} = \frac{80}{0.21} \approx 380.95 \]
Therefore, the PaO2/FiO2 Ratio is \( \text{Ratio} \approx 380.95 \).
