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Glossary on Blood Transfusion
Apheresis blood donation
This type of blood donation involves the use of a machine to selectively collect a specific blood component (red blood cells, white blood cells, platelets or plasma). The other components are then returned back to the donor. The process of apheresis blood donation is also used to collect Stem cells for use in Bone Marrow Transplantation.
Autologous blood donation
Patients scheduled for elective surgery may sometimes be able to donate their own blood to be stored until the date of their surgery. This blood then can be transfused back to them should they require a blood transfusion during or following the surgery. This reduces the risk of receiving blood donated from another person. Autologous donated blood is only given back to the person who donates it. If it is not required for this person, it is discarded.
Blood component
When a blood donor donates a unit of whole blood, the whole blood unit can be separated into different parts (or components). These components are: Red blood cells, platelets, plasma. Each part or component of the blood has a different function. This is the reason why one blood donation can help 3 people since patients receive only the specific part of the blood that is needed.
Blood Transfusion
A medical procedure, ordered by a Physician, that involves the introduction of blood or blood components directly into the blood stream of a patient by using a needle that is inserted into a vein.
Blood product
Plasma from blood can be pooled and further processed into various products to provide specific therapy for patients. These products include proteins such as albumin, immune globulin and factors to reduce bleeding.
Blood donation
Blood is donated voluntarily in Canada, blood donors are not paid. Two agencies collect blood from blood donors – Canadian Blood Services throughout Canada (with the exception of Quebec) and Hema-Quebec in Quebec.
Blood donor testing
All blood donated at Canadian Blood Services or Hema-Quebec is tested before being given to patients for diseases to reduce the risk that the blood or blood component will pass on the disease to the patient. This testing also helps ensure that the blood or blood component will be compatible with the blood of the patient who receives it. The donated blood is tested for the following:
- Hepatitis B
- Hepatitis C
- Human Immunodeficiency Virus (HIV)
- Human T cell Lymphotropic virus (HTLV – virus linked to leukemia)
- Syphilis
- West Nile Virus
- Blood type (ABO and Rh)
- Antibodies to red blood cells
Blood found positive for any of the diseases listed above is not used for transfusion but discarded.
Risks of receiving blood transfusion
The most current published risk* of transmission of infection from blood Transfusion in Canada is:
 |
HIV |
Hepatitis C |
Hepatitis B |
HTLV |
|
1 in 7.8 million |
1 in 2.3 million |
1 in 153,000 |
1 in 4.3 million |
*O’Brien et al Transfusion 2007;47:316-325. |
Directed blood donation
In certain circumstances, family members who have compatible blood types are able to donate blood that can then be stored for use for a relative who may be undergoing elective surgery (usually parent to child).
Blood dilution
This process, also known as hemodilution, can occur during surgery to reduce the need for the use of blood donated by another person and is a type of Autologous donation. Two to three units of the patients blood are removed at the start of surgery and are replaced by fluids. The blood can then be returned to the patient at the end of the surgery if required.
Blood salvage
During or after surgery, patients may lose blood. In some circumstances, blood can be saved into a machine as it is lost during surgery. This blood can then be filtered and returned to the patient during or at the end of the surgery. This reduces the need to receive blood donated by another person.
Blood conservation
A Blood Conservation program is designed to reduce the need for patients to receive blood or blood components donated from another person during or after their surgery. This program may include:
- Autologous donation
- Medication (to boost the patient’s blood levels before surgery)
- Medication to reduce blood loss during surgery
- Blood dilution
- Blood salvage
Red blood cells
These are the cells in blood that contain hemoglobin and give blood its red colour. Red blood cells deliver oxygen to tissues and remove carbon dioxide.
Platelets
These are colourless cells in blood that help to prevent bleeding by clustering and forming a clot at the site of injury.
White blood cells
These cells travel throughout the body in the blood and tissues to help protect against bacteria and viruses. White blood cells attack bacteria and viruses by ‘eating’ them and also by forming ‘antibodies’ to destroy bacteria and viruses. White blood cells can also carry bacteria and viruses though so most are removed from donated blood as part of the processing prior to blood transfusion.
Plasma
Plasma is a protein – salt solution that is the fluid portion of blood. The red blood cells, white blood cells and platelets are suspended in plasma. Plasma is a straw coloured clear liquid that is about 90% water. Plasma helps in the formation of clots to stop the loss of blood and also helps to maintain blood pressure.
Cryoprecipitate
Specific proteins (fibrinogen and clotting factor VIII) can be recovered from processed plasma (precipitate out when plasma is thawed under certain conditions). When transfused this blood component helps blood to clot.
Blood Stem Cells
These cells are capable of developing into many types of blood cells (red blood cells, white blood cells and platelets) and are used to regenerate / repopulate bone marrow during a Bone Marrow Transplant. These are also called hematopoietic progenitor cells.
Transfusion reaction
Although blood transfusions are given to help patients recover from surgery or illness, occasionally, as with many medical treatments, a patient may experience discomfort or a have negative outcome. This ‘reaction’ is most often mild such as a slight fever or rash but can be more serious and can range from a high fever, difficulty breathing or developing an infection, shock or in extreme cases even death. This reaction is also referred to as an Adverse Transfusion Event (ATE).
References:
1. About Blood Transfusion – Information for Patients. 1st ed.
Pamphlet published by Transfusion Ontario Program; 2005.
2. About Blood Transfusion – Information for Nurses and other health care professionals. 2nd ed.
Booklet published by Transfusion Ontario Program; July 2005.
3. O’Brien et al. Current incidence and estimated residual risk of transfusion-transmitted infections in donations made to Canadian Blood Services. Transfusion 2007;47:316-325.
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