Effect of Heparin or Saline Dilution of Blood on Pco2and pH

Abstract

The effect of different dilutions with heparin solutions or saline on blood Pco₂, pH and standard bicarbonate was investigated. Blood was first equilibrated to give about 40 or 60 mmHg Pco₂. The solutions were in equilibrium with room air. The effect on blood Pco₂ etc. could be fully explained by the dilution with a medium having a much lower Pco₂. Thus, correction of the heparin solution to pH 7.40 and Pco₂ 40 mmHg eliminated the effect on Pco₂, pH and standard bicarbonate. With ordinary procedure for blood heparinization (about 2% dilution) the effect is practically negligible.