Blood products are therapeutic substances derived from a single unit of whole blood donation, used to treat specific deficiencies or medical conditions. A blood donation is separated into its individual components because patients rarely require all parts of the blood simultaneously. Modern transfusion medicine focuses on providing only the specific component needed, maximizing the utility of each donation and ensuring targeted therapy.
Cellular Products for Transfusion
This category includes the formed elements of blood, which are primarily responsible for oxygen transport and hemostasis. Packed Red Blood Cells (PRBCs) consist of red cells separated from most of the plasma and platelets through centrifugation. These cells contain hemoglobin, a protein that binds oxygen in the lungs and delivers it to tissues throughout the body.
The primary use for PRBCs is to restore the oxygen-carrying capacity of the blood in patients experiencing symptomatic anemia or significant blood loss from trauma or surgery. A single unit of PRBCs typically increases an adult patient’s hemoglobin level by approximately 1 gram per deciliter. To preserve their function, PRBCs are stored under refrigeration at temperatures between 1°C and 6°C, which maintains their viability for up to 42 days.
Platelets are small, anuclear cell fragments necessary for the initiation of blood clotting. Their function is to adhere to the site of a vessel injury and aggregate, forming a temporary plug to stop bleeding. Platelet transfusions are indicated for treating or preventing bleeding in patients with a low platelet count (thrombocytopenia) or those with dysfunctional platelets.
Platelets can be collected either from multiple whole blood donations and pooled, or from a single donor using an apheresis machine. Unlike red cells, platelets must be stored at room temperature (20°C to 24°C) and kept under continuous gentle agitation to maintain their function. Their storage life is significantly shorter than red cells, typically lasting only five to seven days.
Plasma and Cryoprecipitate
Plasma is the pale yellow, liquid portion of blood composed primarily of water, electrolytes, proteins, hormones, and coagulation factors. Fresh Frozen Plasma (FFP) is prepared by separating plasma from whole blood and freezing it rapidly, typically within eight hours of collection, to preserve the activity of labile clotting factors. This rapid freezing allows FFP to be stored for up to a year or more at ultra-low temperatures, usually -18°C or colder.
FFP is transfused to patients who are actively bleeding or are undergoing an invasive procedure and have multiple clotting factor deficiencies, often due to liver failure or massive blood loss. It provides a broad replacement of all coagulation factors, helping to restore the patient’s ability to form clots. FFP’s use is focused on replacing these coagulation factors and restoring plasma volume.
Cryoprecipitate is a specific derivative of FFP, created by slowly thawing the plasma at a temperature between 1°C and 6°C. This controlled thawing causes a cold-insoluble precipitate to form, which is then separated and refrozen. This product is concentrated with specific large proteins, including fibrinogen, Factor VIII, Factor XIII, and von Willebrand factor.
The primary indication for cryoprecipitate is the replacement of fibrinogen, a protein that forms the stable mesh of a blood clot, in patients with low levels, such as those experiencing major hemorrhage. It is a potent source of this specific clotting protein. Cryoprecipitate is typically administered in pools of multiple units to achieve a therapeutic dose.
Specialized Protein Products
Beyond bulk components and simple derivatives like FFP and cryoprecipitate, extensive industrial processing called fractionation is used to produce highly purified protein products. This complex process involves pooling plasma from thousands of donors and utilizing methods like Cohn cold ethanol fractionation to isolate specific proteins. This purification distinguishes these products from the less processed components used for direct transfusion.
Albumin is the most abundant protein in human plasma, and purified concentrates are used therapeutically to maintain oncotic pressure, the force that keeps fluid within the blood vessels. Concentrated solutions of albumin (often 5% and 25%) are administered to expand circulating blood volume in patients with shock, severe burns, or certain types of liver disease. The hyperoncotic 25% solution draws fluid from the tissues into the circulation, providing significant volume expansion.
Immunoglobulins (IVIG) are purified preparations of antibodies (Immunoglobulin G class) derived from the pooled plasma of thousands of healthy donors. These antibodies are administered intravenously to patients with primary immunodeficiency disorders to replace low levels of protective antibodies, helping to prevent recurrent infections. IVIG is also used in high doses to treat various autoimmune and inflammatory conditions by modulating the immune system’s response.
Concentrated Clotting Factors are highly purified products designed to treat specific, inherited bleeding disorders. For instance, patients with Hemophilia A, who lack Factor VIII, receive Factor VIII concentrate, while those with Hemophilia B receive Factor IX concentrate. These factor concentrates allow for precise dosing and effective prophylactic or on-demand treatment of bleeding episodes, improving the quality of life for individuals with these lifelong conditions.