7.1 Blood Donor Selection, Screening, Collection, and Component Storage

Blood Donor Selection and Screening

The foundation of a safe blood supply begins with the rigorous screening of prospective blood donors. The process involves multiple steps: donor identification, educational materials, a health history questionnaire, and a physical examination. The overarching goal is twofold: to protect the donor from potential harm associated with blood loss and to protect the recipient from transfusion-transmitted infections and other complications.

Physical Examination Requirements

To ensure the safety of the donor, specific physical criteria must be met before an allogeneic whole blood donation can proceed. The AABB (Association for the Advancement of Blood & Biotherapies) sets strict guidelines:

• Age: Generally, donors must be at least 16 or 17 years old, depending on state laws. There is typically no upper age limit, provided the donor is in good health.
• Weight: A minimum weight of 110 lbs (50 kg) is required to tolerate the standard 450-500 mL collection volume without experiencing adverse hypovolemic effects. If a donor weighs less, a proportionate reduction in blood volume drawn and anticoagulant used is mandatory.
• Hemoglobin and Hematocrit: For allogeneic donation, capillary or venous hemoglobin must be >= 12.5 g/dL, or the hematocrit must be >= 38%. For autologous donations (donating for oneself), the requirement is slightly lower: hemoglobin >= 11.0 g/dL or hematocrit >= 33%.
• Blood Pressure: Systolic pressure must be <= 180 mm Hg and diastolic <= 100 mm Hg.
• Pulse: The pulse should be regular and between 50 and 100 beats per minute. Athletes may have a lower heart rate, which is acceptable if evaluated by the medical director.
• Temperature: Must be <= 37.5°C (99.5°F).

Donor Deferrals

Deferrals can be temporary, indefinite, or permanent, depending on the risk posed by the donor's medical history, travel, or behavior.

Temporary Deferrals

• 12 Months: After travel to a malaria-endemic area; after a tattoo or piercing (unless done in a state-regulated facility with sterile needles); after receiving a blood transfusion; after completion of therapy for syphilis or gonorrhea.
• 3 Years: After recovery from malaria, or for a resident of a malaria-endemic country returning to a non-endemic country.
• Medications: Proscar, Propecia, Accutane (1 month); Avodart (6 months); Soriatane (3 years); Tegison (permanent). Aspirin delays platelet donation for 48 hours because it irreversibly inhibits platelet function.

Indefinite or Permanent Deferrals

• History of viral hepatitis after the age of 11.
• Confirmed positive test for HBsAg, anti-HBc, HCV, HIV, or HTLV.
• Risk behaviors for HIV, such as exchanging sex for money or drugs.
• History of Chagas disease or Babesiosis.
• Receipt of human pituitary-derived growth hormone (risk of Creutzfeldt-Jakob Disease, CJD).

Blood Component Preparation and Storage

Whole blood is rarely transfused; instead, it is separated into specialized components: Packed Red Blood Cells (PRBCs), Platelets, Fresh Frozen Plasma (FFP), and Cryoprecipitate. Each component has unique storage temperature and shelf-life requirements.

Packed Red Blood Cells (PRBCs)

PRBCs are used to increase oxygen-carrying capacity. During preparation, plasma is removed, and anticoagulant-preservative solutions are added.

• CPD / CP2D: 21 days at 1-6°C.
• CPDA-1: Contains adenine, extending shelf life to 35 days at 1-6°C.
• Additive Solutions (AS-1, AS-3, AS-5): Provide extra nutrients, extending viability to 42 days at 1-6°C. Note: If the hermetic seal is broken (open system), PRBCs expire in 24 hours if kept at 1-6°C.

Platelets

Platelets are critical for hemostasis and are prepared either from whole blood (Random Donor Platelets) or apheresis (Single Donor Platelets).

• Storage: Must be kept at 20-24°C (room temperature) with continuous gentle agitation.
• Shelf Life: Only 5 days, making them highly susceptible to bacterial contamination. A pH of >= 6.2 must be maintained.

Fresh Frozen Plasma (FFP)

FFP contains all coagulation factors, including the labile factors V and VIII. It is separated and frozen rapidly after collection.

• Storage: Frozen at <= -18°C.
• Shelf Life: 1 year from the date of collection. If stored at <= -65°C, it can last 7 years.
• Thawing: Thawed in a 30-37°C water bath. Once thawed, it must be stored at 1-6°C and transfused within 24 hours. If not used, it can be relabeled as Thawed Plasma (valid for up to 5 days, though factor VIII levels will drop).

Cryoprecipitate Antihemophilic Factor (CRYO)

CRYO is the cold-insoluble portion of plasma that precipitates when FFP is thawed between 1-6°C. It is rich in Fibrinogen (Factor I), Factor VIII, Factor XIII, and von Willebrand Factor (vWF).

• Storage: Frozen at <= -18°C for up to 1 year.
• Thawing: Thawed at 30-37°C. After thawing, it must be kept at 20-24°C (room temperature).
• Shelf Life after Thawing: Must be transfused within 6 hours. If pooled in an open system, it expires in 4 hours.

These storage requirements ensure optimal viability and minimal toxicity, keeping patients safe while maximizing the utility of every donation.