If a venous blood gas sample is left at room temperature, which changes occur in the analytes?

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Multiple Choice

If a venous blood gas sample is left at room temperature, which changes occur in the analytes?

When a venous blood gas sample sits at room temperature, cells in the blood keep metabolizing. They use up oxygen and produce carbon dioxide, and there isn’t immediate gas exchange with the outside air or rapid buffering to counteract this. As a result, the oxygen tension falls, carbon dioxide tension rises, and the increased CO2 lowers the pH by forming more carbonic acid. This relationship is consistent with how CO2 affects pH via the carbonic acid–bicarbonate system. Therefore, the changes you’d expect are a decrease in O2, an increase in CO2, and a decrease in pH. To minimize these changes, samples are typically analyzed promptly or kept on ice.

When a venous blood gas sample sits at room temperature, cells in the blood keep metabolizing. They use up oxygen and produce carbon dioxide, and there isn’t immediate gas exchange with the outside air or rapid buffering to counteract this. As a result, the oxygen tension falls, carbon dioxide tension rises, and the increased CO2 lowers the pH by forming more carbonic acid. This relationship is consistent with how CO2 affects pH via the carbonic acid–bicarbonate system. Therefore, the changes you’d expect are a decrease in O2, an increase in CO2, and a decrease in pH. To minimize these changes, samples are typically analyzed promptly or kept on ice.

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