The Incidence, Degree, and Timing of Hypocalcemia From Massive Transfusion: A Retrospective Review

Background: Electrolyte administration during massive transfusion without readily available calcium laboratory values is likely ubiquitous but not well standardized. We aimed to quantify the incidence, degree, and timing of hypocalcemia during the first 24 hours after initiation of a massive transfusion with the institutional massive transfusion protocol (MTP). We hypothesized that hypocalcemia is prevalent during acute resuscitation (first six hours) despite efforts of the treatment team to replete calcium during active resuscitation. Methods: A retrospective chart review of all patients who underwent MTP at our institution between January 1, 2017, and December 31, 2017, was performed. The primary outcome was hypocalcemia from a massive transfusion during the first six hours after the initiation of the MTP. Secondary outcomes of interest included hypercalcemia, hypomagnesemia, hospital mortality, peak and nadir timing of hypocalcemia and hypercalcemia, calcium supplementation, and calcium supplementation timing. Calcium administration and blood product transfusion is reported relative to the start of the MTP. The association between the total amount of calcium administered and the total number of blood products transfused was assessed. Results: Data from 52 massive transfusions were analyzed. Ninety-seven percent of patients were hypocalcemic during the first six hours of resuscitation. The nadir occurred after median of eight units of blood product were given, (interquartile range {IQR}: 4-16). Calcium supplementation correlated with the total number of blood products transfused (ρ = 0.47, p < 0.01). Patients in whom calcium was supplemented received more blood products when compared to patients in whom calcium was not supplemented (median: 16, IQR: 12-26 vs. median: 9, IQR: 7-12, p <0.01). Conclusions: Hypocalcemia from massive transfusion is common. The incidence of hypocalcemia in MTP has been reported to be 85-97%. Calcium supplementation that is not standardized in MTP may lead to underutilization during massive transfusion and to hypocalcemia in these patients.