218: Evaluation of Calcium Gluconate Repletion Scales at a Tertiary Academic Medical Center

Introduction: Calcium is an essential electrolyte, and while electrolytes such as potassium and magnesium are often administered according to repletion scales, calcium is frequently repleted through one-time medication orders. Minimal data exist regarding the safety and efficacy of calcium gluconate administration via repletion scales. At Brigham and Women’s Hospital (BWH), a calcium gluconate order panel was created to facilitate repletion based on ionized calcium (iCa) levels and implemented in November 2023. This study aimed to describe and evaluate the impact of a calcium repletion scale on safety and efficacy in a critically ill population. Methods: This study was a retrospective pre-post analysis at a tertiary academic medical center deemed exempt by the health system institutional review board. Patients ≥ 18 years admitted to BWH intensive care units (ICUs) between May 2023 to October 2023 (“pre” group) and January 2024 to June 2024 (“post” group) were evaluated until pre-specified n=100 in each group was met. The primary endpoint was the incidence of severe hypocalcemia, defined as ionized calcium (iCa) < 0.85 mmol/L. Secondary endpoints included the incidence of overall hypocalcemia (iCa < 1.12 mmol/L), mild hypocalcemia (iCa 1.0–1.12 mmol/L), moderate hypocalcemia (iCa 0.85–0.99 mmol/L), and time to repletion. Results: A trend toward a lower incidence of severe hypocalcemia was observed in the post-group, with 0.5% of ionized calcium (iCa) measurements in the pre-group and 0.2% in the post-group meeting criteria for severe hypocalcemia (p = 0.12). Mild and moderate hypocalcemia were not significantly different (p=0.39 and p=0.29, respectively). Overall hypocalcemia was similar between the groups (p=0.76). Time from lab results to electrolyte repletion was significantly lower in the post group compared with the pre group (57.6 vs 86.4 minutes, p< 0.01). Conclusions: In this analysis, there were no differences in rates of hypocalcemia, but time to repletion was significantly reduced in the group that was ordered for calcium scales. Standardized calcium gluconate repletion yields efficacious and efficient repletion compared to one-time, non-protocolized repletion practices in critically ill patients.