[Heparin-induced changes in blood gas analysis (author's transl)].

In modern blood gas analysis heparin is used for preventing coagulation in the syringe and the analyzer. If the amount of heparin added is too large the pH of the blood sample falls and so an artificial metabolic acidosis is induced. Consequently the amount of heparin used should be just enough to prevent blood coagulation without changing appreciably the acid-base status of the sample. High concentrations of inspired oxygen have no additional effect on the ability of heparin to alter the pH values.