What factors might impact CO2 levels?

Bicarbonate (CO2) is highly unstable, and it can be impacted by various factors. During the phlebotomy process, factors that may influence CO2 levels include small needle size, prolonged tourniquet time, and inadequate fill volume of Vacutainer tubes. Additionally, medications such as methicillin, nitrofurantoin, tetracycline, thiazide diuretics, and triamterene may influence CO2 levels. The bicarbonate result should be interpreted within the context of other tests and requires clinical correlation for interpretation and clinical decision making. A single high or low result may or may not have medical significance. Generally, this is the case when the test value is only slightly higher or lower than the reference range.