The influence of anticoagulation on acid-base status and blood-gas analysis

The results of acid-base status and blood-gas analysis can be influenced massively by incorrect sampling. We found that the addition of heparin has no great effect on blood-gas measurement. Citric acid and fluoride can also be admixed to blood samples in the usual concentrations without severe side-effects. The major error in the determination of blood gases and acid-base status is a consequence of even minimal dilution: filling the deadspace of a syringe with any diluent leads to unacceptable results. Hence, we conclude that blood specimens for determination of blood gases and acid-base status should be taken in specially prepared syringes containing the anticoagulant in the form of a dry substance. We think that citric acid is also acceptable for anticoagulation. Fluoride should be added in order to minimize alterations of pH due to anaerobic glycolysis.