FACTORS INFLUENCING IONIZATION OF CALCIUM DURING MAJOR SURGICAL PROCEDURES

  • 1 January 1976
    • journal article
    • research article
    • Vol. 143  (6) , 895-900
Abstract
The existence of a clinically feasible Ca electrode makes it possible to obtain rapid, accurate levels Ca2+. It is now possible to study the actual ionization of Ca under normal and abnormal physiologic conditions. The present investigation was directed at changes in Ca2+ during major surgical procedures. The total series of 125 patients was divided into 3 groups according to the type of plasma volume expander: group 1, whole blood alone; group 2, whole blood plus exogenous albumin, and group 3, albumin alone. Ca2+ levels dropped significantly, P < 0.001, in all 3 groups. Although albumin alone produced a decrease in Ca2+, the addition of albumin to whole blood did not result in a greater decline than that experienced with whole blood alone. Chelation with the citrate ion of bank blood preservative was the major factor responsible for the decrease in Ca2+. There was no statistically significant relationship between the extent of the decrease, the total volume of blood, the volume of blood/kg or the rate of transfusion in ml/kg per min. Although the Ca2+ level fell initially, it increased while blood administration continued. In view of these facts, it is difficult to estimate the actual level of Ca2+ at any point during the operation. Twenty patients in the series had Ca2+ levels below 1.25 meq/l, i.e., in the range of 0.5-1.24 meq/l. With the possible exception of 1 patient, no adverse cardiovascular effects could be attributed to the low levels of Ca2+. The administration of exogenous Ca is not necessary during massive transfusion, with the possible exception of bypass open heart procedures and exchange transfusions in children.

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