Monitoring of Ionized Calcium during Human Hepatic Transplantation: Critical Values and Their Relevance to Cardiac and Hemodynamic Management

Abstract

During human hepatic transplantation, ionized calcium (ICa) measured in whole blood with an ion-selective electrode varied greatly from ICa predicted from total calcium (TCa), protein, albumin, and pH, by means of recently published nomograms. Measurement of ICa was necessary because the interaction of citrate in transfused blood and calcium chloride (administered to offset citrate binding) caused large variations in TCa. During hepatic transplantation, ICa and electrolyte measurements were obtained at approximately 15-minute intervals or more frequently if indicated by changing cardiac status. In one patient, hemodynamic instability was accompanied by a large decrease in ICa, which then was followed by cardiac arrest aggravated by myocardial depression from inadequate ICa. Cardiovascular phenomena associated with ionized hypocalcemia suggest that the critical value for ICa should be no more than 0.4 mmol/L (1.6 mg/dL) below the reference range mean. The authors propose critical limits for ICa and discuss their significance in clinical management of tetany, hypotension, arrythmias, and cardiac arrest.

Critical Values:ASCP Practice Parameter

“…20 Clinical assays for ionized calcium are, however, highly method-dependent. Therefore, consensus surveys express critical limits for ionized calcium relative to the midpoint of the normal reference range.…”

“…Therefore, consensus surveys express critical limits for ionized calcium relative to the midpoint of the normal reference range. 19,20 This technique can be applied to other analytes, as the need arises. 12,21 ''…”

How to Stabilize the Level of& ;Ionized Calcium and Citrate during Plateletpheresis

“…Cytapheresis is in effect a massive autotransfusion. Cardiovascular effects of citrate administration and consequent Ca 2+ decrease are well documented in animals [4, 5, 6, 7], in healthy persons [8, 9] and in patients [10, 11, 12, 13, 14, 15]. During cytapheresis, citrate ion (CI) accumulation and Ca 2+ decrease have been well studied [16, 17, 18, 19, 20, 21, 22, 23].…”

Review of anesthesia in liver transplantation

“…Both ionized calcium and potassium disarrangements may result in cardiac arrest. 114,191 The reported incidence rate of cardiac arrest during the LT procedure is 3.3% 114 to 5.5%. 115 The incidence is almost 100-fold higher when compared with that of noncardiac and nontransplantation procedures (which have a rate of 0.01%).…”