Resuscitation strategies for the acutely injured patient in hemorrhagic shock have evolved. Patients benefit from receiving less crystalloid in favor of blood transfusions with balanced ratios of plasma and platelets or whole blood resuscitation. These resuscitation practices are termed Damage Control Resuscitation and have been incorporated into resuscitation protocols in Level I trauma centers across the country. Damage Control Resuscitation represents standard practice for military and civilian trauma. Despite these changes, deaths from traumatic hemorrhage continue to occur in the first hours following trauma center arrival, underscoring the importance of early, novel interventions.

Hypocalcemia following traumatic injury is exceedingly common following severe traumatic injury in patients at risk of hemorrhagic shock. During hemorrhagic shock resuscitation, pathways reliant upon calcium such as platelet function, intrinsic and extrinsic hemostasis, and cardiac contractility are disrupted. Citrate containing transfusion products are known to further reduce calcium levels through chelation during trauma resuscitation. Hypocalcemia has consistently been shown to be independently associated with the risk of large volume blood transfusion and mortality. Current management practices include calcium replacement during the in hospital phase of care in patients receiving blood products. Early calcium replacement in patients at risk of hemorrhage and hypocalcemia may mitigate coagulopathy, maintain hemostasis, improve hemodynamics and outcomes, and may reduce complications attributable to hemorrhagic shock.

Arginine vasopressin is a physiologic hormone released by the posterior pituitary in response to hypotension and is commonly used as a vasopressor for critically ill patients for the treatment of hypotension due to multiple causes including sepsis. Prolonged hemorrhagic shock has the potential to alter systemic vasomotor tone which can progress to refractory/recalcitrant hypotension. Patients receiving resuscitation for hemorrhage are at risk of vasopressin deficiency. Vasopressin may improve hemostasis by enhancing platelet function and augmenting clot formation. Vasopressin infusion soon after injury in patients in hemorrhagic shock has been demonstrated to be safe and result in a reduction in blood transfusion requirements and a lower incidence of deep venous thrombosis.

Whole blood, red cells, and blood components are a precious and limited resource. Trauma resuscitation adjuncts such as early calcium and vasopressin may provide benefit when transfusion products are limited and may provide additional benefit even when transfusion capabilities remain robust. Due to their action on coagulation and hemodynamic cascades in the injured patient, these resuscitation adjuncts have the potential to interact and provide additive benefit to the injured patient. However, safety and efficacy of prehospital calcium and early in hospital vasopressin remain inadequately characterized. Enrolled patients may participate in the prehospital phase (calcium), in-hospital phase (vasopressin), or both. The aims of the CAlcium and VAsopressin following Injury Early Resuscitation (CAVALIER) trial are to determine the efficacy and safety of prehospital calcium supplementation and early in hospital vasopressin infusion as compared to standard care resuscitation in patients at risk of hemorrhagic shock and to appropriately characterize any additive effect of both resuscitation adjunct interventions.