Which sample is used to evaluate gas exchange and acid-base status?

Which sample is used to evaluate gas exchange and acid-base status?

• A. Blood gasses
• B. Serum
• C. Plasma
• D. CBC

Answer: (A)

Measuring gas exchange and acid-base status relies on quantifying the dissolved gases and the pH of blood, which is obtained from an arterial blood gas sample. Arterial blood reflects the lungs’ ability to oxygenate and remove carbon dioxide, so it provides accurate PaO2, PaCO2, and pH values that define acid-base balance. Serum or plasma come from clotted blood and only reflect the liquid components, not the gas tensions. CBC assesses blood cells, not gas exchange or acid-base status. So the best choice is the blood gas sample.

Measuring gas exchange and acid-base status relies on quantifying the dissolved gases and the pH of blood, which is obtained from an arterial blood gas sample. Arterial blood reflects the lungs’ ability to oxygenate and remove carbon dioxide, so it provides accurate PaO2, PaCO2, and pH values that define acid-base balance. Serum or plasma come from clotted blood and only reflect the liquid components, not the gas tensions. CBC assesses blood cells, not gas exchange or acid-base status. So the best choice is the blood gas sample.