A Comparison of Serum Ionized Calcium in Arterial and Mixed Venous Blood During CPR

Abstract

Changes in the actual ionized calcium level (aCa 2+ ) of serum in arterial and mixed venous blood during CPR were investigated in 22 patients with intrinsic cardiopulmonary arrest. Measurements were carried out at an average of 5.4 ± 0.6 minutes (group 1) and 30 minutes (group 2) after the beginning of CPR, using simultaneously taken blood samples. The aCa 2+ of groups 1 and 2 revealed no difference between arterial and mixed venous bloods. As CPR proceeded, the aCa 2+ of both bloods diminished, and group 2 had a significantly lower value than did group 1 (arterial blood: 2.36 ± 0.04 mEq/L vs 2.09 ± 0.09 mEq/L, P P 2+ serum level measurements was carried out in relation to survivors and nonsurvivors and to the presence or absence of a witness at the time of the cardiac arrest. In all groups, there was no difference in aCa 2+ between arterial and mixed venous blood. As CPR proceeded, however, the aCa 2+ showed a significant decrease in all groups. This decrease was accompanied by a pH increase in arterial blood of patients with a witnessed cardiac arrest and in mixed venous and arterial blood of survivors.