Certified Pulmonary Function Technologist (CPFT) Practice Exam

How do air bubbles in an arterial blood gas (ABG) sample affect the results?

1. PO2 decrease, PCO2 decrease, pH decrease

2. PO2 increase, PCO2 decrease, pH increase

3. PO2 decrease, PCO2 increase, pH increase

4. PO2 increase, PCO2 increase, pH decrease

The correct answer is: PO2 increase, PCO2 decrease, pH increase

In analyzing the effect of air bubbles in an arterial blood gas (ABG) sample, it's essential to understand that air bubbles introduce oxygen (O2) directly into the blood sample while also allowing carbon dioxide (CO2) to escape. This interaction typically results in an elevation of the partial pressure of oxygen (PO2) due to the increased gas presence from the air bubbles. The presence of bubbles can also lead to a decrease in the partial pressure of carbon dioxide (PCO2). The escape of CO2 into the atmosphere (due to diffusion from the blood into the bubbles) leads to a reduced concentration of CO2 in the sample. This drop in PCO2 can, in turn, result in an increase in blood pH since the removal of CO2 reduces the amount of carbonic acid formed in the blood, shifting the balance towards a more alkaline state. Thus, the correct assessment indicates that with the introduction of air bubbles, there is an increase in PO2, a decrease in PCO2, and an increase in pH. This is consistent with option B, showcasing how air contamination affects the analysis of blood gases. Understanding these dynamics is crucial for accurate interpretation of ABG results, as misinterpretation could lead to misguided