What effect do air bubbles have on arterial blood gas (ABG) readings specifically on PaCO2?

When air bubbles mix with a blood sample, they can have a profound effect on the partial pressure of carbon dioxide (PaCO2) readings obtained from arterial blood gas (ABG) analysis. The presence of air bubbles in the sample introduces an environment where there is a higher concentration of oxygen and a lower concentration of carbon dioxide compared to the blood.

As a result, the PaCO2 in the sample decreases significantly, often approaching a value near zero torr. This occurs because the carbon dioxide diffuses out of the blood sample and into the bubbles, while the oxygen from the bubbles can enter the blood. This exchange alters the normal gas composition, leading to an artificially low measurement of PaCO2 when tested. In a clinical context, recognizing the influence of air bubbles on ABG results is crucial to ensure accurate interpretation and appropriate patient management.