"Blood Products" is a term used to describe products that contain any components of normal blood. When an individual donates a unit of the blood, the donation is usually "whole blood". A unit of whole blood can be broken down into many different products or blood components. Patient's can abe given just the part of the blood that they need, allowing many patients to benefit from one donation.

A CBC (Complete Blood Count) is a blood test that is performed very frequently in the critical care unit. It allows us to measure the amount and type of red and white blood cells and the number of platelets. A "blood smear" or "differential" (often called a "diff") is a detailed look at the CBC under a microscope. A differential provides information about the appearance of each type of cell and can be helpful in diagnosing many diseases.

Blood is divided into plasma (the water portion) and cells. About 45% of the volume of whole blood is cells. About 1% of the cells are white blood cells (called leukocytes) and platelets (called thrombocytes). Leukocytes fight infection. The leukocyte or white blood cell count helps us to identify infection. Neutrophils are a type of white blood cell that is the first to rise following acute inflammation (injury) or infection. Platelets are the cells that make up a clot. A low platelets count can cause bleeding.

The remainder of the blood cells are red blood cells (called erythrocytes). Inside each red blood cell is approximately 300 hemoglobin molecules. Hemoglobin is a protein that carries oxygen. Each hemoglobin can carry 4 oxygen molecules. Red blood cells play a critical role in carrying oxygen from the lung to the tissues. When the red blood cells reach the organs and tissues, the hemoglobin molecule will release some of the oxygen to allow it to move into the cells. A low hemoglobin level indicates that the red blood cell count is low, and is called anemia.

Mild anemia is common in critically ill patients. Bleeding and lab testing can cause a loss of hemoglobin. Red blood cells may not live as long during serious illness, and it is harder to make new ones. Mild anemia is generally tolerated well, however, severe anemia makes it hard to carry enough oxygen to the tissues. We may need to treat anemia with a transfusion of red blood cells.

Although blood transfusions are very safe in Canada, there is always a very small chance of passing a virus from a donor to a recipient. Some blood products undergoing processing that reduces this small risk even further. Even though the risk is extremely low, we are careful to only give blood products when they are absolutely needed. Before a blood transfusion is given, the patient and donor blood are checked carefully to make sure the blood type can be accepted by the patient.

Following blood donation, the red blood cells are removed from the sample and stored as a unit of "packed red cells" (or packed cells). Packed cells are given to increase the hemoglobin and red blood cell level, but do not contain plasma. A preservative is added to prevent the blood from clotting.

The plasma that is separated from a blood donation can be used for a number of purposes. Plasma contains proteins called clotting factors (or coagulation factors). These proteins are needed to make blood clot. When donated plasma is frozen shortly after donation, the clotting factors are preserved. We can give a patient a transfusion of Plasma if the blood is not clotting properly.

Plasma also contains platelets. Platelets are the cells that stick together when needed to form a blood clot. Platelets are usually removed from donated plasma and stored separately. This allows more than one patient to benefit from a donated sample. We can give plasma to one person and give platelets to another.

When a patient needs a platelet transfusion, one unit of donated blood will not provide enough platelets, therefore, the platelets from several donations are "pooled" or mixed together. Platelets may need to be given if the patient has a very low platelet count and is at risk for bleeding.




Last Updated: October 23, 2014


Image 1: Packed Red Blood Cells







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Last Updated October 23, 2014 | © 2007, LHSC, London Ontario Canada