Autotransfusion techniques reduce the need for allogenic blood transfusion. Patients are transfused with their own blood via either preoperative self-donation or intraoperative blood salvage.
PREOPERATIVE AUTOLOGOUS DONATION
Patients donate their own blood at weekly intervals prior to surgery; patients may donate three or more units prior to elective surgery. Donated blood is stored, often without the need for freezing, and may be used perioperatively to treat anemia. Consideration must be given to the patients’ overall medical condition, including hemoglobin and cardiac status. Relative contraindications for autologous donation include severe aortic stenosis, coronary artery disease, low initial hematocrit, and low initial blood volume. Though patients receive their own blood, the use of autotransfusion does not eliminate the chance of human clerical errors that may occur.
Anemia typically limits donation. Erythropoietin and iron supplementation prior to donations effectively increases blood collection; however, these strategies may be expensive. The costs, administrative efforts, potential wasted autologous blood, and resulting anemia must be weighed against the benefits of possibly avoiding allogenic transfusion.
ACUTE NORMOVOLEMIC HEMODILUTION
Two to four units of blood may be withdrawn from a patient early in the operative course, with the withdrawn blood volume replaced with an equivalent volume of crystalloid. Crystalloid is typically substituted for blood in a 3:1 ratio; or colloid replacement can be used in a 1:1 ratio. Hemodynamic monitoring and serial hemoglobin checks during acute normovolemic hemodilution (AHN) confirm tolerance of the procedure as notable blood volume shifts occur. Additionally, care must be taken to ensure that anticoagulant in the collection bags mixes thoroughly with removed blood to prevent clotting. Depending on the patient’s medical status, goal of dilution for hematocrit is 27%-33%. Acute normovolemic hemodilution theoretically permits low-hematocrit blood loss during the operation, and patient’s own blood may be transfused later, as needed. Since the blood does not leave the operating room, the risk of clerical error is minimized. Few data exist to prove efficacy of the technique. As with preoperative autologous donation (PAD), use of ANH must weigh the effort required to donate and monitor the patient against the theoretical benefits.
PERIOPERATIVE BLOOD SALVAGE
Blood salvage (ie, CellSaver; Haemonetics Corp., Braintree, MA) allows surgical blood loss collection, processing, and transfusion back to the patient. Salvage techniques should be considered for significant blood loss surgical procedures, including cardiac, spinal instrumentation, liver transplant, and trauma surgery. Contraindications include pus or fecal material exposure, amniotic fluid contamination, or certain types of malignant cell exposure during surgery. Additionally, intraoperative salvage should be avoided in patients exposed to antibiotic irrigants or microfibrillar collagen hemostat (Avitene Hemostat [Davol, Warwick, RI]).
Surgical blood loss is collected via suction and anticoagulated as it leaves the surgical field. Collected blood undergoes centrifuge processing to separate red blood cells from other blood components, such as fat, clot, free hemoglobin, clotting factors, ...