Patients are typically transfused in the emergency department to treat acute blood loss and/or circulatory shock. The goal of transfusion is to improve oxygen delivery to tissues, provide intravascular volume expansion, and replace missing or depleted clotting factors. Great care must be taken to ensure that the correct blood product is delivered to the correct patient.
There are few indications for the use of whole-blood transfusion. Although whole-blood transfusion would seem ideal to replace acute blood loss, storage of whole blood inactivated platelets, and other factors. Therefore, whole blood is fractionated to its components for transfusion.
Packed red blood cells (PRBCs) are prepared from whole blood by removing most platelets and/or white cells. A single unit of PRBC has 250 mL and raises an adult's hemoglobin by 1 g/dL (hematocrit by 3%). In children, 10 to 15 mL/kg of PRBCs raises the hemoglobin level by approximately 2 to 3 g/dL (hematocrit by 6% to 9%). PRBCs increase oxygen-carrying capacity in anemic patients.
The decision to transfuse PRBC is based on individual clinical judgment, taking into account patient's hemodynamic status, underlying medical condition, tolerance for anemia, and risk of end-organ ischemic injury. Adequate oxygen delivery in healthy normovolemic patients can be maintained with hemoglobin levels as low as 7 g/dL, although patients with comorbid conditions may require transfusion at higher levels of hemoglobin. The usual indications for PRBC transfusion include (a) acute blood loss about 30% of blood volume (1500 mL in adult), (b) acute hemorrhage, (c) unstable trauma patients based on inadequate response to an initial 2-L bolus of IV crystalloid or 40 mL/kg in children; and (d) symptomatic anemia with hemoglobin <7 g/dL or being at-risk for ischemic events, such as patients with hemoglobin <8 to 9 g/dL who have sepsis or ischemic heart or brain injury.
Type and cross-match assesses ABO/Rh blood type, the presence of antibodies, and patient and donor blood compatibility. Blood type can be determined in approximately 15 minutes, whereas it takes about 45 to 60 minutes to perform a serologic cross-match.
In critical situations, where there is no time to perform a complete ABO/Rh-typing, group O/Rh-negative blood (“universal donor”) can be given to patients without waiting for a complete type and cross-match. Type O/Rh-positive blood may be used if Rh-negative blood is unavailable, but should be avoided in girls and women of childbearing potential. Before transfusion, blood for baseline laboratory tests, type, and crossmatching should be obtained.
Packed red blood cells may be further treated to minimize complications in special patient populations, such as neonates, transplant and patients on transplant list, patients who have received prior transfusions, pregnant patients, immunocompromised patients, and patients with hypersensitivity to plasma. Options include leukocyte-reduced, irradiated, frozen deglycerolized, washed, and Cytomegalovirus-negative PRBCs.