Taking a slight detour into the trauma critical care realm today…
BLUF: Favor aggressive calcium supplementation following trauma, especially when patient requires transfusion. Recent evidence is pointing towards a signal for improved outcomes.
Hypocalcemia in trauma is common. Roughly half to two-thirds of trauma patients are hypocalcemic on arrival, driven by both shock physiology and citrate chelation from blood products. Some authors advocate for hypocalcemia to be added as the fourth element of a "lethal diamond" alongside coagulopathy, acidosis, and hypothermia. See reference 1&2 for good discussions of this physiology.
Time for a grain of salt: A recent article in JTACS advocates for favoring calcium chloride during whole-blood or massive transfusion and was associated with improved early survival. Calcium chloride at a threshold of at least 1 g per 2 units of low-titer O whole blood was independently associated with an 84% (!) reduction in 24-hour mortality, with the benefit strongest at this 1:2 ratio and weaker at less aggressive thresholds. (LOTS of caveats with this finding, but interesting nonetheless).
Current major civilian guidelines say only that hypocalcemia should be prevented, with limited specificity on timing or dose, and the Joint Trauma System recommends 1 g calcium after the first unit and after every fourth unit thereafter. The current CAVALIER trial is evaluating prehospital calcium specifically. Those results and other recent literature could push major trauma organizations to update their recommendations in the near future.
References
https://pubmed.ncbi.nlm.nih.gov/41995161/
https://pmc.ncbi.nlm.nih.gov/articles/PMC13082262/
https://clinicaltrials.gov/study/NCT05958342