Background: Hypocalcemia is cited as a complication of massive transfusion. However, this is not well studied as a primary outcome in trauma patients. Our primary outcome was to determine if transfusion of packed red blood cells (pRBC) was an independent predictor of severe hypocalcemia (ionized calcium ≤ 3.6 mg/dL).
Methods: Retrospective, single-center study (01/2004-12/2014) including all trauma patients ≥ 18 yo presenting to the ED with an ionized calcium (iCa) level drawn. Variables extracted included demographics, interventions, outcomes, and iCa. Regression models identified independent risk factors for severe hypocalcemia (SH).
Results: Seven thousand four hundred and thirty-one included subjects, 716 (9.8%) developed SH within 48 h of admission. Median age: 39 (Range: 18-102), systolic blood pressure: 131 (IQR: 114-150), median Glasgow Coma Scale (GCS): 15 (IQR: 10-15), Injury Severity Score (ISS): 14 (IQR: 9-24). SH patients were more likely to have depressed GCS (13 vs 15, p < 0.0001), hypotension (23.2% vs 5.1%, p < 0.0001) and tachycardia (57.0% vs 41.9%, p < 0.0001) compared to non-SH patients. They also had higher emergency operative rate (71.8% vs 29%, p < 0.0001) and higher blood administration prior to minimum iCa [pRBC: (8 vs 0, p < 0.0001), FFP: (4 vs 0, p < 0.0001), platelet: (1 vs 0, p < 0.0001)]. Multivariable analysis revealed penetrating mechanism (AOR: 1.706), increased ISS (AOR: 1.029), and higher pRBC (AOR: 1.343) or FFP administered (AOR: 1.097) were independent predictors of SH. SH was an independent predictor of mortality (AOR: 2.658). Regression analysis identified a significantly higher risk of SH at pRBC + FFP administration of 4 units (AOR: 18.706, AUC:. 897 (0.884-0.909).
Conclusion: Transfusion of pRBC is an independent predictor of SH and is associated with increased mortality. The predicted probability of SH increases as pRBC + FFP administration increases.