Understanding and Calculating Blood Oxygen Saturation (SpO2)

Oxygen saturation is a measure of how much oxygen is binding to hemoglobin molecules in the blood compared with how much hemoglobin is available. It is given as a percentage. In a healthy person, oxygen saturation is typically 96 percent or greater. You can calculate an approximate saturation value using arterial oxygen pressure measurements. The arterial oxygen pressure level is typically measured in a lab setting using electrodes that can sense dissolved oxygen in the blood.

Instructions

• 1

  Add 150 to the value of the arterial oxygen pressure.

• 2

  Cube the arterial pressure by multiplying it by itself twice.

• 3

  Add the answer from Step 1 to the answer in Step 2. Divide 1 by the result.

• 4

  Multiply the result of Step 3 by 23,400. Add 1 to the answer.

• 5

  Divide 1 by the number you found in Step 4. This is the estimated oxygen saturation level. Multiply by 100 to convert to a percentage.