Serum or Plasma Oxygen Saturation (Partial Pressure)

What Is This Test Measuring?

The test measures the partial pressure of oxygen in your blood, which reflects how effectively your lungs transfer oxygen from inhaled air into your bloodstream. This is typically done using a blood gas analysis, often paired with other measurements like carbon dioxide levels or pH.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms like shortness of breath, fatigue, or signs of poor oxygenation (e.g., confusion, rapid heartbeat). It’s also used in monitoring conditions like chronic obstructive pulmonary disease (COPD), pneumonia, or during surgeries requiring precise oxygen management.

How Is the Test Performed?

A small blood sample is taken from a vein, usually in your arm. The sample is analyzed in a lab to measure oxygen saturation levels, often alongside other blood gas metrics like carbon dioxide or pH.

What Do the Results Mean?

Results are compared to standard ranges for healthy individuals, though exact values can vary based on factors like altitude, health conditions, or medical devices (like ventilators). Low levels may indicate lung problems, while high levels could suggest conditions like polycythemia (increased red blood cells).