Which statement about air bubbles in arterial blood gas samples is true?

Which statement about air bubbles in arterial blood gas samples is true?

• A. Air bubbles should be avoided because they alter gas measurements.
• B. A small amount of air bubbles improves gas equilibration.
• C. Air bubbles have no impact on pH readings.
• D. Air bubbles are beneficial for sample mixing.

Answer: (C)

Air bubbles in arterial blood gas samples introduce a separate gas phase that can exchange with the blood, distorting the measured values. The bubble contains ambient air, which has much higher oxygen and negligible carbon dioxide compared with arterial blood. Gases diffuse between the blood and the bubble until their partial pressures try to equalize, so PaO2 can appear falsely high and PaCO2 can become falsely low. This shift in carbon dioxide pressure also alters the blood’s buffering system, leading to a pH that does not reflect the patient’s true arterial blood. Because of these potential distortions, bubbles must be avoided to ensure accurate gas measurements. The idea that bubbles don’t affect pH or that they help mixing is incorrect; the correct practice is to prevent bubbles and recollect if any are present.

Air bubbles in arterial blood gas samples introduce a separate gas phase that can exchange with the blood, distorting the measured values. The bubble contains ambient air, which has much higher oxygen and negligible carbon dioxide compared with arterial blood. Gases diffuse between the blood and the bubble until their partial pressures try to equalize, so PaO2 can appear falsely high and PaCO2 can become falsely low. This shift in carbon dioxide pressure also alters the blood’s buffering system, leading to a pH that does not reflect the patient’s true arterial blood. Because of these potential distortions, bubbles must be avoided to ensure accurate gas measurements. The idea that bubbles don’t affect pH or that they help mixing is incorrect; the correct practice is to prevent bubbles and recollect if any are present.