Hypocalcaemia upon arrival (HUA) in trauma patients who did and did not receive prehospital blood products: a systematic review and meta-analysis

Purpose Hypocalcaemia upon arrival (HUA) to hospital is associated with morbidity and mortality in the trauma patient. It has been hypothesised that there is an increased incidence of HUA in patients receiving prehospital transfusion as a result of citrated blood products. This research aimed to determine if there was a difference in arrival ionised calcium (iCa) levels in trauma patients who did and did not receive prehospital transfusion. Methods We conducted a systematic review and meta-analysis of patients with an Injury Severity Score (ISS) > / = 15 and an iCa measured on hospital arrival. We then derived mean iCa levels and attempted to compare between-group variables across multiple study cohorts. Results Nine studies reported iCa on arrival to ED, with a mean of 1.08 mmol/L (95% CI 1.02-1.13; I-2 = 99%; 2087 patients). Subgroup analysis of patients who did not receive prehospital transfusion had a mean iCa of 1.07 mmol/L (95% CI 1.01-1.14; I-2 = 99%, 1661 patients). Transfused patients in the 3 comparative studies had a slightly lower iCa on arrival compared to those who did not receive transfusion (mean difference - 0.03 mmol/L, 95% CI - 0.04 to - 0.03, I-2 = 0%, p = 0.001, 561 patients). Conclusion HUA is common amongst trauma patients irrespective of transfusion. Transfused patients had a slightly lower initial iCa than those without transfusion, though the clinical impact of this remains to be clarified. These findings question the paradigm of citrate-induced hypocalcaemia alone in trauma. There is a need for consensus for the definition of hypocalcaemia to provide a basis for future research into the role of calcium supplementation in trauma.