Anesthesia Technologist Practice Exam

What effect does a significant size air bubble have on the PaCO2 measurement in an arterial blood gas sample?

1. Increase

2. Decrease

3. No effect

4. Unable to determine

The correct answer is: Decrease

When analyzing arterial blood gas samples, the presence of a significant size air bubble can lead to a decrease in the measured partial pressure of carbon dioxide (PaCO2). This occurs because the air bubble contains a higher concentration of oxygen and a lower concentration of carbon dioxide compared to venous blood. When the blood sample is exposed to atmospheric air via an air bubble, the dissolved carbon dioxide in the blood can equilibrate with the air in the bubble. Since the air has a much lower concentration of carbon dioxide, the carbon dioxide in the blood will move into the bubble to establish equilibrium, effectively reducing the PaCO2 level in the sample. This results in an inaccurate measurement of PaCO2, making the blood appear to have a lower level of carbon dioxide than it actually does. In contrast, the other options are less accurate relative to the physiological principles at play. For instance, claiming that the presence of an air bubble would increase or have no effect on PaCO2 does not align with the gas exchange dynamics dictated by partial pressure gradients. The inability to determine a clear effect suggests a misunderstanding of the sample handling processes affecting gas solubility and equilibria. Hence, the correct understanding is that a significant air bubble will indeed lead to a decrease in