Blood Banking: Collection and Processing

• Blood banking is the process of collecting, testing, processing, and storing blood and its components for transfusion purposes
• It involves various steps to ensure the safety and compatibility of blood products for patients in need

Blood Collection

• Blood is typically collected from volunteer donors
• Donors must meet specific eligibility criteria, including age, weight, health status, and hemoglobin levels
• A medical screening and health history questionnaire are used to assess donor suitability and minimize the risk of transmitting infectious diseases
• The blood collection process, known as phlebotomy, involves inserting a needle into a vein, usually in the arm, and collecting blood into a sterile collection bag containing an anticoagulant
• The anticoagulant prevents the blood from clotting during storage

Blood Processing

• After collection, blood undergoes processing to separate it into its components: red blood cells, plasma, platelets, and cryoprecipitate
• Centrifugation is commonly used to separate blood components based on density
• Red blood cells are typically stored in an additive solution that provides nutrients and helps maintain their viability
• Plasma can be frozen to create fresh frozen plasma (FFP), which contains clotting factors and other plasma proteins
• Platelets can be separated and stored for transfusion to patients with thrombocytopenia or platelet dysfunction
• Cryoprecipitate is a plasma fraction rich in clotting factors, including factor VIII and fibrinogen, and is used to treat bleeding disorders

Blood Testing

• Collected blood undergoes rigorous testing to ensure safety and prevent transfusion-transmitted infections
• Testing includes:
  • ABO and Rh blood typing to determine the donor's blood group
  • Antibody screening to detect unexpected red blood cell antibodies in the donor's plasma
  • Testing for infectious diseases such as HIV, hepatitis B and C, syphilis, and West Nile virus
• Nucleic acid testing (NAT) is used to detect viral genetic material and can identify infections in the early stages
• If any test results are positive, the blood unit is discarded and the donor is notified

Blood Storage

• Blood components are stored under specific conditions to maintain their viability and prevent bacterial contamination
• Red blood cells are typically stored at refrigerated temperatures (1–6°C) for up to 42 days, depending on the additive solution used
• Platelets are stored at room temperature (20–24°C) with continuous agitation for up to 5–7 days
• Plasma is frozen at -18°C or lower for up to one year to preserve clotting factors
• Cryoprecipitate is also stored frozen and thawed before transfusion

Blood Group Systems

• The ABO blood group system is the most important blood group system in transfusion medicine
• It consists of four main blood groups: A, B, AB, and O
• Individuals with type A blood have A antigens on their red blood cells and anti-B antibodies in their plasma
• Individuals with type B blood have B antigens on their red blood cells and anti-A antibodies in their plasma
• Individuals with type AB blood have both A and B antigens on their red blood cells and neither anti-A nor anti-B antibodies in their plasma
• Individuals with type O blood have neither A nor B antigens on their red blood cells and both anti-A and anti-B antibodies in their plasma
• The Rh blood group system is another important blood group system
• The most significant Rh antigen is the D antigen
• Individuals who have the D antigen on their red blood cells are Rh-positive, while those who lack the D antigen are Rh-negative

Blood Compatibility Testing

• Compatibility testing, also known as crossmatching, is performed to ensure that the donor's blood is compatible with the recipient's blood
• The process involves:
  • ABO and Rh typing of the recipient's blood
  • Antibody screening to detect unexpected red blood cell antibodies in the recipient's plasma
  • A crossmatch, in which the recipient's plasma is mixed with the donor's red blood cells to check for agglutination (clumping) or hemolysis (destruction) of the red blood cells
• If agglutination or hemolysis occurs, the blood is considered incompatible and cannot be transfused

Transfusion Reactions

• Transfusion reactions are adverse events that occur as a result of a blood transfusion
• They can range from mild to life-threatening
• Acute hemolytic transfusion reactions are caused by the destruction of red blood cells due to incompatible blood
• Symptoms can include fever, chills, chest pain, back pain, and hemoglobinuria (hemoglobin in the urine)
• Allergic reactions are caused by antibodies in the recipient's plasma reacting to allergens in the donor's blood
• Symptoms can include hives, itching, and facial swelling
• Febrile non-hemolytic transfusion reactions (FNHTR) are caused by cytokines released from white blood cells in the transfused blood component
• Symptoms include fever and chills
• Transfusion-related acute lung injury (TRALI) is a serious complication characterized by acute respiratory distress and pulmonary edema
• It is caused by antibodies in the donor's plasma reacting to antigens on the recipient's neutrophils or pulmonary endothelial cells
• Transfusion-associated circulatory overload (TACO) occurs when the recipient's cardiovascular system is unable to handle the volume of transfused blood
• Symptoms include shortness of breath, cough, and edema

Autologous Transfusion

• Autologous transfusion involves collecting and storing a patient's own blood for transfusion at a later date, typically before a planned surgery
• This eliminates the risk ofalloimmunization and transfusion-transmitted infections
• Preoperative autologous donation involves collecting blood several weeks before surgery
• Acute normovolemic hemodilution involves collecting blood at the start of surgery and replacing it with crystalloid or colloid solutions to maintain blood volume
• The collected blood is then reinfused at the end of surgery
• Cell salvage involves collecting blood lost during surgery, washing and filtering it, and reinfusing it back into the patient

Blood Alternatives

• Blood alternatives are being developed to address the limitations of blood transfusions, such as the risk of transfusion-transmitted infections and the limited availability of blood
• Oxygen-carrying solutions, such as hemoglobin-based oxygen carriers (HBOCs) and perfluorocarbons (PFCs), are designed to deliver oxygen to tissues
• Volume expanders, such as crystalloid and colloid solutions, are used to increase blood volume and maintain blood pressure
• Hemostatic agents, such as recombinant factor VIIa and fibrin sealants, are used to control bleeding