Processing

This section discusses how the blood is actually collected. This is obviously a critical step, and the methods used depend on what specific blood components are needed and the donor’s eligibility

Think of collection methods falling into two main categories: the traditional Whole Blood donation and the more targeted Apheresis procedures. Both require meticulous technique to ensure donor safety and product quality

Whole Blood Collection

This is the classic method most people picture when they think of donating blood

• Concept: A standard, fixed volume of blood (typically 450-500 mL) is collected directly from the donor’s vein into a sterile bag containing an anticoagulant-preservative solution
• Procedure
  1. Site Selection Usually a large, prominent vein in the antecubital area (the crook of the elbow)
  2. Aseptic Preparation This is crucial to prevent bacterial contamination of the blood product! The site is vigorously scrubbed using an FDA-approved disinfectant (often an iodine compound like povidone-iodine or, for donors sensitive to iodine, chlorhexidine gluconate and isopropyl alcohol). The aim is to remove surface bacteria and kill microbes deeper in the skin follicles. The prepared area must not be touched again before venipuncture
  3. Venipuncture A sterile, single-use needle (typically 16-17 gauge) attached to the collection bag tubing is inserted smoothly into the vein
  4. Collection Blood flows by gravity into the primary collection bag. The bag contains a specific amount of anticoagulant (like CPD, CPDA-1, or CPD with an additive solution like AS-1, AS-3, AS-5, or AS-7 in a satellite bag)
  5. Mixing The bag must be mixed gently and frequently (either manually or using an automated mixer/scale) during collection to ensure the blood immediately combines with the anticoagulant, preventing clots
  6. Volume Monitoring The collection is stopped when the target volume is reached (often monitored by weight using the scale). Scales also clamp the tubing automatically
  7. Sample Collection Before removing the main needle, tubes are filled with blood samples from the diversion pouch or collection line for mandatory infectious disease testing and blood typing. A diversion pouch on the collection bag collects the first few mL of blood (containing the skin plug potentially contaminated during venipuncture) and diverts it away from the main unit, further reducing contamination risk
  8. Needle Removal & Post-Care The needle is withdrawn, pressure is applied to the site, and a sterile bandage is applied. The donor rests and is given refreshments
• Anticoagulant/Preservative Solutions: These solutions (like CPD, CPDA-1, AS-1) prevent clotting and provide nutrients to keep red cells viable during storage. The type of solution dictates the shelf-life of the red blood cells (e.g., 21 days for CPD, 35 days for CPDA-1, 42 days for AS solutions)
• Outcome: A unit of Whole Blood, which is typically processed in the lab into components: Red Blood Cells (RBCs), Plasma (usually Fresh Frozen Plasma - FFP), and sometimes Platelets (though platelet concentrates from whole blood are less common now due to the popularity of apheresis platelets)
• Donation Frequency: Typically, donors must wait at least 56 days (8 weeks) between whole blood donations

Apheresis Collection (Hemapheresis)

Apheresis (from Greek, meaning “to take away” or “separate”) is a more specialized collection method where whole blood is drawn, a specific component is separated and collected using a machine, and the remaining components are returned to the donor during the same procedure

• Concept: Allows for the collection of a larger volume of a specific component (like platelets, plasma, or red cells) from a single donor compared to what can be separated from one unit of whole blood
• General Procedure
  1. Similar donor qualification and rigorous site preparation as whole blood
  2. Venipuncture is performed, often in both arms (one for draw, one for return) or sometimes using a single, larger needle capable of alternating draw/return cycles
  3. Blood is drawn into a sterile, closed system connected to the apheresis machine
  4. Anticoagulation An anticoagulant, typically citrate, is added as the blood enters the machine. Citrate prevents clotting by binding calcium
  5. Separation The machine uses centrifugation to separate whole blood into its components based on density (RBCs are heaviest, then WBCs, platelets, and plasma is lightest)
  6. Collection & Return The desired component is diverted into a collection bag, while the other components (e.g., red cells, plasma) are returned to the donor through the return line
  7. Monitoring The donor is continuously monitored throughout the procedure (which takes longer than whole blood donation, often 1-2 hours) for any adverse reactions, particularly those related to citrate
• Types of Apheresis Procedures
  • Plateletpheresis (Platelets): Collects concentrated platelets. A single apheresis platelet unit is equivalent to the platelets derived from 5-6 whole blood donations. Frequency: Donors can often donate platelets more frequently than whole blood (e.g., every 7 days, up to 24 times per year, regulations vary)
  • Plasmapheresis (Plasma): Collects plasma (FFP or Source Plasma for further manufacturing). Frequency: Can be done relatively frequently (e.g., every 4 weeks for FFP, even more often for Source Plasma under specific programs)
  • Red Cell Apheresis (Double Red Cell / “Power Reds”): Collects two units’ worth of red blood cells. Donors need higher hemoglobin/hematocrit levels and meet weight/height requirements. Frequency: Less frequent than whole blood (e.g., every 112 days / 16 weeks) because more RBCs are removed
  • Granulocyte Apheresis: Collects granulocytes (neutrophils). Less common, usually for specific patients with severe infections unresponsive to antibiotics. Often requires donor pre-treatment with medications (like G-CSF and/or corticosteroids) to boost their granulocyte count
  • Multicomponent Apheresis: Collects two or more components simultaneously (e.g., platelets and plasma, or platelets and red cells). Efficient use of a single donation
• Advantages of Apheresis
  • Higher yield of the targeted component from one donor
  • Reduces recipient exposure to multiple donors (e.g., one apheresis platelet unit vs. a pool of 5-6 whole blood-derived platelets)
  • Allows donors to give specific needed components more frequently (platelets, plasma)
• Donor Considerations
  • Longer procedure time
  • Citrate Reaction: Because citrate anticoagulant is returned to the donor (unlike in whole blood donation where it stays in the bag), donors can experience symptoms of temporary hypocalcemia (low calcium) like tingling around the lips or fingers, chills, or rarely, muscle cramps. This is managed by slowing the return rate or giving calcium supplements (like Tums)

Key Elements Common to All Methods

• Donor Safety & Comfort: Constant monitoring, managing reactions promptly
• Aseptic Technique: Paramount to prevent bacterial contamination
• Accurate Labeling: Ensuring the unit is correctly labeled and linked to the donor record and test samples
• Quality Control: Regular checks on equipment (scales, apheresis machines, sealers, etc.)

Key Terms

• Whole Blood Donation: Collection of a standard unit (approx. 450-500 mL) of blood into a bag containing anticoagulant-preservative solution. The unit is later separated into components
• Apheresis (Hemapheresis): A procedure where whole blood is drawn from a donor, a specific component (like platelets, plasma, or red cells) is separated and collected using a machine, and the remaining components are returned to the donor
• Anticoagulant-Preservative Solution: Solutions like CPD, CPDA-1, or those containing Additive Solutions (AS) used in whole blood collection bags to prevent clotting and maintain red cell viability during storage
• Citrate: The anticoagulant typically used in apheresis procedures. It works by chelating (binding) calcium, which is necessary for coagulation. Can cause temporary hypocalcemia symptoms in the donor
• Aseptic Technique: Procedures used to prevent microbial contamination, critically important during skin preparation and venipuncture in blood collection
• Diversion Pouch: A small pouch integral to the blood collection bag tubing that collects the initial few mL of blood drawn, diverting the skin plug and potential surface bacteria away from the main collection bag
• Venipuncture: The act of puncturing a vein with a needle for the purpose of drawing blood
• Plateletpheresis: An apheresis procedure specifically designed to collect platelets
• Plasmapheresis: An apheresis procedure specifically designed to collect plasma
• Red Cell Apheresis (Double Red Cell Donation): An apheresis procedure designed to collect two doses of red blood cells
• Citrate Reaction/Toxicity: Symptoms experienced by some apheresis donors due to the temporary reduction of ionized calcium caused by the return of citrated blood. Symptoms often include tingling sensations (paresthesia)