血液回收技術(自體輸血）

From surgeryencyclopedia

Blood Salvage(自體輸血）

Definition

Blood salvage is the recovery of a patient's own blood from the surgical site to be re-administered to the patient.

Purpose

Pre-operative blood salvage can be performed prior to the surgical incision during the induction of anesthesia. This blood is collected to be administered post-operatively, because the clotting factors and platelets are protected from activation and destruction caused by the surgery. This procedure is most often used if cardiopulmonary bypass (use of a heart-lung machine) will be instituted. If the blood is not given to the patient, it will be discarded. Pre-operative blood donation or autologous blood donation is a coordinated donation process planned prior to a scheduled surgical procedure, but it is not considered blood salvage.
Blood salvage is performed during surgical procedures when the risk of significant blood loss is expected. The recovered blood is collected, processed, and readministered to the patient, decreasing or preventing the need for allogeneic (from a donor) blood product administration. If the blood is not given to the patient, it will be discarded.
Post-operative blood salvage is used to collect blood from the surgical cavity as the wound heals. The blood is collected, may or may not be processed, and returned to the patient. If the blood is not given to the patient, it will be discarded.
Administration of the patient's own blood eliminates the risk of transfusion-transmitted viral disease and transfusion reactions. Patients with multiple red blood cell antibodies or rare blood types benefit by blood salvage during the perioperative (during surgery) and postoperative period. Shortages of rare blood types can put the patient at risk for cardiovascular collapse caused if hemorrhage occurs during the surgical procedure.
Some Jehovah's Witnesses patients refuse allogeneic blood donation. Blood salvage provides an opportunity for autologous blood donation for these patients. Certain modifications in collection technique make autologous blood donation an acceptable treatment for members of this faith.
Neurological, vascular, cardiac, liver transplant, and orthopedic procedures make extensive use of blood salvage techniques. Patients having surgical procedures involving amniotic fluid, malignancies, bowel contamination, or microfibrillar collagen materials are not eligible for blood salvage. In the presence of amniotic fluid or bowel contamination, thorough rinsing of the surgical site may allow for blood salvage.

Description

Preoperative blood salvage
The patient will be provided with cardiac monitoring prior to the initiation of autologous blood collection. A venous access site will be gained with a catheter. The 500–1,000 ml of whole blood is collected into a transfusion container treated with anticoagulant. The container is properly labeled for the patient and clearly marked "AUTOLOGOUS DONOR." The blood can be stored for six hours if refrigerated, and will be destroyed if not used within that time.
Blood collected in this manner is not processed further, but stored for later administration. The whole blood product provides not only red blood cells, but more importantly, plasma proteins including clotting factors and platelets. This technique is most often associated with cardiopulmonary bypass, since the heart-lung machine can damage clotting factors and platelets. The pre-operative collection protects the blood components.

Perioperative blood salvage
During surgery, the surgeon uses suction in the surgical cavity to collect blood. Anticoagulant is mixed with the blood at the tip of the suction apparatus. The blood is filtered as it is collected into a container. From this collection container the blood may be placed into a transfusion container for direct administration to the patient. This blood will be anticoagulated and will contain all plasma proteins, including activated clotting factors and platelets. More commonly, the blood is processed by centrifugation. The blood is centrifuged to separate the red blood cells from the plasma. The plasma is removed as saline enters the centrifuge to wash the blood. Washing the blood removes anticoagulation, plasma-free hemoglobin, and plasma proteins, including activated clotting factors and platelets. This product is called washed packed red cells. After washing is complete, the blood is collected into a transfusion container free of anticoagulant since all clotting factors have been removed during washing. The container is properly labeled for the patient and clearly marked "AUTOLOGOUS DONOR." The blood can be stored for six hours if refrigerated, and will be destroyed if not used within that time.

Postoperative blood salvage
Postoperative blood salvage is used to remove shed blood from the surgical cavity that has been closed at the completion of the surgical procedure. At wound closure, a catheter is left in the cavity and penetrates the skin for connection to the collection reservoir. If the blood is collected from the chest cavity, no anticoagulation is required. If the blood is collected from a joint, it must receive anticoagulation during collection. The blood from the chest cavity is usually reinfused without additional processing, but may be washed. Blood collected from a joint must be washed prior to infusion. Washing involves centrifugation of the blood to separate the red blood cells from the plasma. In the plasma are the anticoagulant-free hemoglobin and plasma proteins, including activated clotting factors and platelets. Once the red blood cells and plasma are separated, saline is introduced to the centrifuge to displace the plasma with the end product collected into a transfusion container. The final product is called washed packed red blood cells. The container is properly labeled for the patient and clearly marked "AUTOLOGOUS DONOR." The blood can be stored for six hours if refrigerated, and will be destroyed if not used within that time.

Normal results

The patient will receive autologous blood donation when the red blood cell volume, as measured by hemoglobin or hematocrit values, falls below the desired level, commonly 18–21% or 6–7 g/dl, respectively. These values will be dictated by the physician in the orders for patient care.
If with the patient's condition is acceptable, autologous blood donation with preoperative blood collection occurs immediately following the termination of cardiopulmonary bypass. Treatment of low red cell volume is not best accomplished with this technique. Instead, this technique supports coagulation.
Blood collected postoperatively will be administered as need for maintenance of blood pressure or red cell volume.
The patient benefits from blood salvage by the elimination of the risk of blood-transmitted virus or blood transfusion reactions. Blood transfusion reactions are experienced by about 10% of recipients for each unit transfused.

Resources

Books
Spiess, Bruce D., et al., eds. *Perioperative Transfusion Medicine. *Baltimore: Williams & Wilkins, 1998.

Other
"Guidance for Autologous Blood and Blood Components." *Autologous Blood and Blood Components. *Division of Blood and Blood Products, HFB-400, Bethesda, MD 20892. March 15, 1989 [cited April 3, 2003]. http://www.fda.gov/cber/bldmem/031589.pdf .

Allison Joan Spiwak, MSBME

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