Research Units are designed to provide clear summaries of results and impacts of research conducted at Canadian Blood Services. Written by Canadian Blood Services researchers in collaboration with the knowledge mobilization team, these summaries will help in further disseminating research findings to facilitate informed decision-making.
After cardiac surgery, it’s common for patients to lose so much blood that they need to replace some blood components (red blood cells, platelets, plasma) through transfusion. Excessive bleeding can happen when fibrinogen, a protein essential to the blood clotting process, is in short supply in a patient’s blood. Having abnormally low levels of fibrinogen for reasons that are not hereditary is a condition called acquired hypofibrinogenemia.
Hypofibrinogenemia is treated by replacing the patient’s fibrinogen with either cryoprecipitate or fibrinogen concentrate. Although both products come from blood plasma, they differ in purity, fibrinogen content and shelf life. They also have different storage and shipping requirements. In North America, cryoprecipitate is the most common product used, while in most European countries, fibrinogen concentrate is the preferred product.
This study examined whether fibrinogen concentrate performs as well as cryoprecipitate in patients who have cardiac surgery and require fibrinogen replacement.
When a unit of red blood cells is selected for transfusion, compatibility is determined by the blood type of the donor and the recipient, but not their sex. However, observational studies that have looked at the relationship between donor characteristics and patient outcomes suggest that identifying a compatible donor may involve knowing more than just their blood type. Research findings point to donor characteristics like sex, age and parity (the number of times a woman has carried a pregnancy to a viable stage), as factors that may affect patient outcomes after blood transfusion.
This study summarized evidence from studies that examined the impact of sex-mismatched transfusions (when a patient receives a red blood cell transfusion from a donor of the opposite sex) on patient outcomes.
Inflammation is characterized by redness, heat, swelling, pain and loss of function. It is a sign that the immune system is fighting something harmful. While helpful to fight injury or infection, excessive or inappropriate inflammation can cause disease. Inflammatory diseases include autoimmune diseases, which occur when the immune system attacks the body with inappropriate immune and inflammatory responses. Approximately 80 disorders are considered autoimmune, affecting an estimated 4.5 per cent of people. Autoimmune diseases include rheumatoid arthritis, type 1 diabetes and Crohn’s disease.
Blood type is determined by whether specific molecules (called antigens) are present or absent on the surface of red blood cells. There are over 300 red blood cell antigens and over 30 blood group systems, including the well-known ABO and Rh groups. Some combinations of antigens are far less common than others, making some blood types rarer than others. Blood is considered rare if the combination of antigens is only found in one person in 500, and is very rare if only found in one person in 1000.
At Canadian Blood Services, blood safety is paramount. At every step along the path from donor to recipient, measures are taken to protect recipients from receiving blood that contains infectious disease agents such as viruses or bacteria. Donors are screened for risk factors, blood donations are tested for infectious disease agents, and production processes and storage conditions that limit the risk are use.
Plasma is the protein-rich, fluid portion of blood. It contains proteins important for blood clotting and fighting infections. Biological drugs derived from plasma are essential, life-saving treatments for a variety of diseases. They include coagulation factors used to treat bleeding disorders and immunoglobulins, including intravenous immunoglobulin (IVIg), which are used to treat immune disorders. To manufacture these drugs, blood plasma from thousands of donations is pooled together, treated to reduce the risk of transfusion-transmitted infections, and fractionated into components that are used to manufacture biological drugs.
Quality control testing ensures manufacturers continue to provide the highest quality products. For blood product manufacturers, quality control testing ensures patients receive a safe and effective product. For example, for red blood cell concentrates (RCCs), a blood product given to patients who have low iron or hemoglobin levels due to injury or illness, quality control includes sterility testing, and determining the integrity and quality of the red blood cells.
Exposure to cells or tissues that are genetically different to your own, for example through blood transfusion, a tissue or organ transplant, or pregnancy, comes with a risk. If the immune system identifies these cells and tissues as foreign, it will mount an immune response against the transfused or transplanted cells or tissues. To avoid these serious reactions, the blood and tissue type of recipients and donors is determined before transfusion or transplantation. To ensure compatibility, cross-matching can also be done, using laboratory tests to determine if a specific donor is compatible with a specific recipient.
Platelets are tiny cell fragments that circulate at the periphery of the blood flow near the blood vessel wall. If they encounter damage, they become “activated”, changing shape and forming a clot. Platelets are essential for wound repair and to stop blood loss after injury. If a person has low platelet numbers or their platelets are not functioning well, they are at risk of bleeding.
High-dose intravenous immunoglobulin (IVIg) is given to treat patients with immune and inflammatory diseases. It is usually an effective treatment that is well-tolerated. However, high-dose IVIg can cause an adverse reaction in which the patient’s red blood cells burst (hemolysis). The hemolysis is often mild and self-limiting, but it can become severe. Some patients who develop hemolysis may require transfusion of red blood cells to treat the resulting anemia.