Subclavian Venous Blood Gas (Partial Pressure of Oxygen and Carbon Dioxide)

Why This Test Is Done

Your healthcare provider may order this test if you have symptoms like shortness of breath, rapid breathing, or signs of poor oxygenation (such as blue lips or confusion). It’s also used in situations requiring precise monitoring of blood gases, like during surgery, severe illness, or mechanical ventilation.

What to Expect Before the Test

You’ll typically lie down while a healthcare professional inserts a needle into your subclavian vein. The blood sample is drawn into a tube, and the test measures the gases without further preparation. Most people find it quick and painless, though you may feel a brief pinch.

What the Results Mean

The results show your blood’s oxygen (pO₂) and carbon dioxide (pCO₂) pressures, which help determine if your lungs are working efficiently. Abnormal levels may indicate conditions like respiratory failure, lung disease, or metabolic issues.

Common Conditions Monitored

This test is often used to monitor patients with chronic lung diseases (e.g., COPD), those on ventilators, or those recovering from severe illness. It also helps diagnose conditions like pneumonia, asthma flare-ups, or metabolic acidosis.