Enter the fraction of inspired oxygen, mean airway pressure, and arterial oxygen tension into the calculator to determine the Oxygenation Index.

Oxygenation Index Formula

OI = (FiO2 * MAP * 100) / PaO2

The following formula is used to calculate the Oxygenation Index (OI). Variables:

  • OI is the Oxygenation Index FiO2 is the fraction of inspired oxygen MAP is the mean airway pressure PaO2 is the arterial oxygen tension

To calculate the Oxygenation Index, multiply the fraction of inspired oxygen by the mean airway pressure, then multiply the result by 100. Divide this result by the arterial oxygen tension.

What is an Oxygenation Index?

The Oxygenation Index (OI) is a calculation used in intensive care medicine to measure the severity of lung disease, such as acute respiratory distress syndrome (ARDS). It is calculated using the fraction of inspired oxygen (FiO2), the mean airway pressure (MAP), and the arterial oxygen concentration (PaO2). A higher OI indicates more severe lung disease and a greater need for supportive care or intervention.

How to Calculate the Oxygenation Index?

The following steps outline how to calculate the Oxygenation Index (OI).

  1. First, determine the fraction of inspired oxygen (FiO2).
  2. Next, determine the mean airway pressure (MAP).
  3. Next, determine the arterial oxygen tension (PaO2).
  4. Next, gather the formula from above = OI = (FiO2 * MAP * 100) / PaO2.
  5. Finally, calculate the Oxygenation Index.
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

FiO2 = 0.6

MAP = 10

PaO2 = 80