Intraoperative blood salvage (IOS), also known as cell salvage, is a specific type of autologous blood transfusion.
Specifically IOS is a medical procedure involving recovering blood lost during surgery and re-infusing it into the patient.
It is a form of autotransfusion.
Normovolemic! hemodilution is performed in approximately 20% of cardiac surgery departments and allows for the transfusion of the patient’s whole blood, which is withdrawn before the patient receives heparin and undergoes cardio pulmonary bypass.
This technique improves the coagulation profile after cardiopulmonary bypass and reduces activation of inflammatory pathways, consumption of clotting factors and platelets owing to activation of circuit contracts, the need for allogeneic red cell transfusion, and blood viscosity, thereby contributing to improved microcirculatory perfusion.
The procedure is frequently used in cardiothoracic and vascular surgery, during which blood usage has traditionally been high.
Advances in preventing transmission of hepatitis B virus (HBV), hepatitis C virus (HCV), AIDS/HIV, HTLV-I/II, West Nile virus (WNV), syphilis, Chagas disease, Zika virus, and transfusion-transmitted bacterial infection have improved blood transfusion safety.
Human errors such as misidentifying patients and drawing blood samples from the wrong person is more of a risk than transmissible diseases in many developed nations.
Much more common risks of allogeneic transfusion include allergic transfusion reactions as well as febrile non-hemolytic transfusion reactions.
Transfusion risks include transfusion related acute lung injury (TRALI), transfusion associated circulatory overload (TACO) and transfusion-associated immunomodulation.
TRALI is a potentially life-threatening condition with symptoms such as dyspnea, fever, and hypotension occurring within hours of transfusion.
TACO is a much more common potentially life-threatening condition involving respiratory compromise within hours of a transfusion.
TACO must be suspected when there is respiratory distress with other signs, including pulmonary edema, unanticipated cardiovascular system changes, and evidence of fluid overload during or up to 24 hours after transfusion.
Transfusion-associated immunomodulation, which may suppress the immune response and cause adverse effects such as a small increase in the risk of postoperative infection.
Other risks such as Creutzfeldt–Jakob disease (vCJD), an invariably fatal disease, for which currently there is no approved tests for which to screen blood donors for this disease.
In many industrialized countries 5% or less of the eligible population are blood donors.
The global medical community have moved from allogeneic blood (blood collected from another person) towards autologous transfusion, in which patients receive their own blood.
Another impetus for autologous transfusion is the position of Jehovah’s Witnesses on blood transfusions.
Cell processors are red cell washing devices that collect anticoagulated shed or recovered blood, wash and separate the red blood cells (RBC) by centrifugation or filtration.
After, the washed RBCs can be returned to the same patient by reinfusion.
RBC washing devices can help remove byproducts in salvaged blood such as activated cytokines, anaphylatoxins, and other waste substances that may have been collected in the reservoir suctioned from the surgical field.
However, they also remove viable platelets, clotting factors, and other plasma proteins essential to whole blood and homeostasis.
Direct transfusion is a blood salvaging method associated with cardiopulmonary bypass (CPB) circuits or other extracorporeal circuits (ECC) that are used in surgery such as coronary artery bypass grafts (CABG), valve replacement, or surgical repair of the great vessels.
The ECC circuit contains a significant volume of diluted whole blood that can be harvested in transfer bags and re-infused into patients.
Residual CPB blood is fairly dilute ([Hb] = 6–9 g/dL; 60–90 g/L) compared to normal values (12–18 g/dL; 120–180 g/L) and can also contain potentially harmful contaminants such as activated cytokines, anaphylatoxins, and other waste substances that have been linked to organ edema and organ dysfunction and need a diuretic to reverse.
Acute normovolemic hemodilution (ANH) is a form of autologous transfusion where whole blood is collected from a patient at the start of surgery into a standard blood collection bag with anticoagulant with the simultaneous replacement of intracellular volume using acellular fluids such as normal saline.
The patient’s own blood is re-infused at the end of the surgical case when any bleeding has stopped.
Hemofiltration or ultrafiltration devices constitute the third major type of blood salvage in operating rooms.
Ultrafiltration devices filter the patient’s anticoagulated whole blood.
The filter process removes unwanted excess non-cellular plasma water, low molecular weight solutes, platelet inhibitors and some particulate matter through hemoconcentration, including activated cytokines, anaphylatoxins, and other waste substances making concentrated whole blood available for reinfusion.
Hemofilter devices return the patient’s whole blood with all the blood elements and fractions including platelets, clotting factors, and plasma proteins with a substantial Hb level.
Coagulation and homeostasis are immediately improved with the return of concentrated autologous whole blood.
Intraoperative.normovolumic hemodilution is performed in approximately 20% of cardiac surgery departments and allows for the transfusion of the patient’s whole blood, which is withdrawn before the patient receives heparin and undergoes cardio pulmonary bypass.
This technique improves the coagulation profile after cardiopulmonary bypass and reduces activation of inflammatory pathways, consumption of clotting factors and platelets owing to activation of circuit contracts, the need for allogeneic red cell transfusion, and blood viscosity, thereby contributing to improved microcirculatory perfusion.
However, among adults undergoing cardiac surgery normovolemic hemodilution does not reduce the number of patients receiving allogeneic red cell transfusion.