Blood Component & Testing - Part 2

Blood Components and Testing

Red Blood Cells (RBCs)

  • Overview of RBCs

    • Discussed as one of the main components from a whole blood unit.

  • Freezing RBCs

    • Stored at 1°C to 6°C for up to six days before being frozen.

    • Cryoprotectant used is glycerol, which is commonly employed for freezing.

  • Deglycerized Red Cells

    • Process involves thawing and washing cells to remove leukocytes, platelets, and plasma.

    • Two types of glycerol used: high glycerol and low glycerol.

    • High Glycerol: Most common, uses uncontrolled freezing.

    • Low Glycerol: Uses liquid nitrogen for controlled freezing.

  • Storage and Shelf Life

    • Frozen RBCs kept at -65°C and can be stored for ten years.

  • Usage in Rare Phenotypes

    • Frozen RBCs utilized for rare phenotypes, such as donors without the Solano antigen.

    • Used in certain disease states like paroxysmal nocturnal hemoglobinuria (PNH) and IgA deficiency.

    • Patients with IgA deficiency may use autologous donations, freezing their own blood for later use.

  • Military Use

    • Frozen RBCs used by military to maintain blood inventories.

  • Post-Thawing

    • After thawing and deglycerizing, RBCs must be used within 24 hours due to glycerol remnants.

Fresh Frozen Plasma (FFP)

  • Definition and Purpose

    • FFP is the fluid component of blood that contains all clotting factors.

    • Most common plasma component derived from whole blood.

  • Preparation

    • Blood must be collected without delay, ideally less than eight hours old.

    • Logistics may require timely courier transport to limit delays.

  • Indications for Use

    • Utilized for clotting deficiencies and trauma to maintain hemostasis.

    • Administered during surgeries and in cases of liver disease where clotting factors are produced.

    • Effective in treating disseminated intravascular coagulation (DIC).

  • Preparation Process

    • Blood is centrifuged; packed cells settle at the bottom.

    • Plasma is then expressed into a satellite bag to keep red cells separate.

    • Must be frozen at -18°C or lower after initial processing.

  • Thawing and Storage

    • Thawing methods: preferably in a water bath rather than an FDA-approved microwave.

    • Thawed FFP stored at 1°C to 6°C for 24 hours, used within that time frame due to manipulation.

  • Plasma Exchange

    • Plasma exchange involves replacing patient plasma with FFP to dilute certain conditions.

Other Plasma Products

  • Cryoprecipitate Reduced Plasma

    • Produced from thawed FFP; centrifuging separates cryoprecipitate.

    • Contains albumin, factors II, V, VII, IX, X, XI, and von Willebrand's factors.

    • Must be refrozen within 24 hours of preparation.

  • Single Donor Plasma

    • Prepared by freezing a unit within 8 to 24 hours of collection.

    • Can be stored for five days at 1°C to 6°C.

    • Commonly used for patients with active bleeding or multiple clotting factor deficiencies.

  • Soldier Plasma Storage

    • Similar storage conditions and shelf life to FFP, minus cryoprecipitate.

Platelet Concentrates

  • Production

    • Created by centrifuging platelet-rich plasma from whole blood through hard spins (3,600 to 5,000 RPM for 5-7 minutes).

    • Plasma is removed, retaining a small volume for platelet suspension.

  • pH and Concentration

    • Target pH must be greater than or equal to 6.2.

    • Minimum of 5.5 × 10^10 platelets must be present in the concentrate.

    • Historical context of pH measurement methods and their inadequacies discussed.

  • Storage and Shelf Life

    • Platelet concentrates stored at 20°C to 24°C under gentle agitation, only good for five days.

    • Pooled platelets have a shorter shelf life of four hours.

  • Donor Criteria

    • Must label platelets from donors who have taken aspirin, as it can affect platelet function.

  • Platelet Lesions

    • Concerns include bacterial contamination leading to increased risk factors due to temperature and handling.

    • Issues with ATP, ADP levels, and implications for platelet viability if pH falls below target.

Indications for Use of Platelets

  • General Usage

    • Used in actively bleeding patients with thrombocytopenia (commonly defined as a platelet count lower than 50,000/μl).

    • Cancer patients with induced thrombocytopenia typically see counts lower than 20,000/μl, necessitating transfusions.

    • Oncology practices recognize counts below 10,000/μl as critical.

  • Platelet Apheresis

    • Required for patients with previous HLA exposure to ensure compatibility.

    • Reduces exposure risks by limiting platelet donations to one donor rather than multiple.

Cryoprecipitate

  • Contents

    • Comprises von Willebrand factor, factor VIII, factor XIII, and fibrinogen.

  • Preparation

    • Created from frozen FFP; thawed at 1°C to 6°C, leading to the precipitation of cryoprecipitate.

    • Requires separation and refreezing.

  • Storage

    • Good at -18°C or lower for one year; thawed cryo valid for six hours.

  • Indications for Use

    • Supplementation for patients with deficiencies in factor XIII or fibrinogen.

    • Previously utilized as a fibrin sealant in various surgical procedures (e.g., cardiac, dental).

    • Current advancements include pharmaceutical alternatives for treatment of hemophilia A and von Willebrand disease.