Arterial Blood Carbon Dioxide Partial Pressure (PaCO₂)

Why It’s Done

Your healthcare provider may order this test if you have symptoms like shortness of breath, rapid breathing, chest pain, or if you’re at risk for conditions like respiratory failure, heart disease, or kidney problems. It’s also used during surgeries, intensive care, or before procedures that require deep sedation.

What to Expect

A small needle is inserted into an artery (often in your wrist or arm) to draw a blood sample. You may feel a brief pinch, but the procedure is quick. The test is usually done in a hospital or clinic setting.

Interpretation Basics

Results help determine if your lungs are working properly or if your body is retaining too much CO₂, which can affect your blood pH. Abnormal levels may indicate issues like hyperventilation, lung disease, or metabolic conditions.

Common Conditions Linked to Results

High PaCO₂ levels (hypercapnia) can cause respiratory acidosis, leading to fatigue, confusion, or even coma. Low levels (hypocapnia) may suggest overbreathing or lung overinflation. Your provider will discuss findings in relation to your symptoms and medical history.