What is the impact of too much liquid heparin in an ABG sample?

In the context of arterial blood gas (ABG) sampling, adding too much liquid heparin can significantly impact the results. Heparin is an anticoagulant used to prevent clotting in blood samples, and while it's essential for accurate gas exchange measurements, an excess can lead to dilution of the sample.

When there is too much heparin, it primarily dilutes the plasma component of the blood sample. This dilution can lead to a decrease in measured carbon dioxide (PaCO2) levels, resulting in calculated values that skew towards zero. The reason is that the heparin can alter the partial pressures of gases in the sample, leading to an inaccurately low measurement of carbon dioxide.

In a normal blood gas scenario, carbon dioxide levels reflect the respiratory function and metabolic state. An unusually low PaCO2 due to excessive heparin may not accurately represent the patient’s physiological status, creating potential misinterpretations and clinical decisions. Therefore, an accurate concentration of the blood gas components is critical for making proper assessments in clinical settings.