The following is a summary of “Defining the optimal calcium repletion dosing in patients requiring activation of massive transfusion protocol,” published in the August 2023 issue of Emergency Medicine by Robinson et al.
Massive transfusion protocols (MTP) frequently lead to severe hypocalcemia due to the calcium-binding properties of citrate in blood components. The objective of this study is to ascertain the ideal ratio of citrate in grams (g) to deplete calcium in milliequivalents (mEq) (Citrate: Ca) that can effectively decrease 30-day mortality. This was a retrospective, single-centered, cohort study conducted at a level 1 trauma center to assess trauma and surgical patients requiring Massive Transfusion Protocol (MTP) activation between January 1, 2010, and July 31, 2021. Patients presenting with severe hypocalcemia at baseline, as indicated by ionized calcium (iCa) levels below 0.9 mmol/L, were compared to patients who did not exhibit severe hypocalcemia. The main objective was to ascertain the ideal ratio of citrate grams to calcium mEq to decrease mortality in patients undergoing a massive transfusion protocol (MTP).
The secondary endpoints encompass mortality rates at 24 hours and 30 days, utilization of blood components in massive transfusion protocol (MTP), and the specific type of calcium employed. In total, 501 individuals underwent screening for eligibility. Of the total number of patients, 193 were deemed ineligible and excluded from the study. This resulted in a final sample size of 308 patients. Among these patients, 165 individuals (53.6%) exhibited a serum ionized calcium (iCa) level below 0.9 mmol/L within 24 hours, while 143 patients (46.4%) had an iCa level equal to or greater than 0.9 mmol/L within the same time frame. The citrate to calcium ratio for each patient did not show a significant association with mortality at 24 hours (P = 0.79) or 30 days (P = 0.91) when the median repletion citrate to calcium ratio was 1.97 (interquartile range 1.14–2.91).
The mortality rate was the lowest when the Citrate: Ca ratio was 2 for both mortality within 24 hours and mortality within 30 days. No significant disparities in 24-hour or 30-day mortality rates were observed regarding repletion ratios, as indicated by the findings of this study. A Citrate: Ca ratio ranging from 2 to 3 in patients undergoing Massive Transfusion Protocol (MTP) was found to be effective in achieving a normalized ionized calcium (iCa) level within 24 hours of MTP initiation, irrespective of the initial iCa level. Additional prospective studies will be required to ascertain the ideal Citrate: Ca ratio from a medical standpoint.