Effects of anticoagulants on acid-base and blood gas estimations.

The use of excessive amounts of heparin to anticoagulate blood samples for pH and blood gas analysis leads to erroneously low PCO2 results, whereas pH and PO2 are relatively unaffected. Derived base deficit values accordingly will be high. Dilution is seldom less than 6% but may exceed 40%, particularly when sampling fron neonates. Sodium citrate and Heller-Paul oxalate solutions were found to be suitable alternatives to heparin, whereas EDTA was not.