Air bubbles in an arterial blood gas sample are most likely to affect which measurement?

• A. Alter PaO2 measurement
• B. Alter pH
• C. Increase base deficit
• D. Increase PaCO2

Answer: (A)

Air bubbles introduce a separate gas phase that exchanges gas with the blood before analysis. Oxygen diffuses from the bubble, which is exposed to ambient air and has a higher PO2, into the blood, making the measured PaO2 falsely elevated. While CO2 and pH can be affected as gases diffuse, the change in PaO2 is the most direct and reliably observed effect of a bubble in an arterial blood gas sample. To avoid this, ensure the sample is bubble-free and analyzed promptly.