If an ABG sample cannot be analyzed immediately, which storage/handling practice is recommended?

• A. Store at 37°C
• B. Leave at room temperature in a bag
• C. Freeze at -20°C
• D. Place on ice and shield from air, analyze promptly

Answer: (D)

Preserving an arterial blood gas sample after collection requires slowing metabolic activity and preventing gas diffusion. After collection, blood cells keep metabolizing, which alters oxygen and carbon dioxide levels and pH. Placing the sample on ice slows enzymatic activity and gas production/consumption, helping keep PaO2, PaCO2, and pH close to the patient’s true values. Shielding the sample from air prevents gas exchange with the environment, preserving the blood’s original gas tensions. Analyzing promptly then captures an accurate snapshot of the patient’s status.

Storing at body temperature would speed up changes in gas tensions and pH. Leaving the sample at room temperature in a bag allows ongoing metabolism and gas exchange with ambient air. Freezing would cause cellular damage and affect the integrity of the specimen, making results unreliable.