14 March 2019 The transfusion may consist of blood components : Red blood cells; Platelets; Plasma. Substances involved in the formation and normal functioning of blood may also be transfused: Fibrinogen; Coagulation factors; Prothrombin complex; Cryoprecipitate; Fibrin glue; Albumin; Immunoglobulins. The products to be transfused are prepared from blood donations from voluntary donors . After it is taken, the donor’s blood is typed and tested for various diseases. It is then separated into its various components , which can be transfused, processed , packed and kept in optimal storage conditions until needed. In what situations is a blood transfusion carried out? It is always up to the doctor to decide whether there is a need for a particular therapeutic procedure, depending on the individual characteristics of each person and their particular situation. Most patients will never need transfusions when they are suffering from a disease, even when moderate blood loss occurs. This is because within a few weeks new blood cells are produced that replace the lost ones. However, when a large amount of blood is lost , transfusion of blood or blood components may be the only way to achieve timely replacement . Generally speaking, a blood transfusion or blood components may be required in the following situations: When a large amount of blood is lost; When there is loss and/or impairment of the functioning of one of its components; in particular, during or after surgical intervention or giving birth; Accidents involving significant blood loss; Patients treated for blood diseases; Severe anaemia, cancer or leukaemia. Where possible, before a patient receives a transfusion, a sample of their blood is sent for typing . Only afterwards is the batch of blood or component of the blood compatible with the patient chosen . The product is then administered via a catheter into a vein , in the same way as serum. Most patients feel nothing while undergoing a transfusion. In rare cases, mild and temporary reactions (e.g. an increase in body temperature) can occur, which are easily resolved with medical treatment or by slowing down the rate of transfusion. Serious reactions are very rare . What is blood typing? Blood typing is the determination of the type or group of blood . It is performed in accordance with the ABO classification (A, B, AB and O blood) and the presence of the rhesus factor (Rh+ and Rh-). In view of these two groups of antigens, blood groups may be: A Rh+ (or A+); A Rh- (or A-); B Rh+ (or B+); B Rh- (or B-); AB Rh+ (or AB+); AB Rh- (or AB-); O Rh+ (or O+); O Rh- (or O-). The importance of the type of blood in transfusions is due to the fact that not all blood types are compatible with one another . Blood types classified according to the ABO system have the following characteristics: Type A - has A antigens in the red blood cells and anti-B antibodies in plasma; Type B - has B antigens in the red blood cells and anti-A antibodies in plasma; Type AB - has A and B antigens in the red blood cells and has no antibodies in plasma; Type O - has no A or B antigens in the red blood cells and has anti-A and anti-B antibodies in plasma. Taking into account groups A, B, AB and O , the following l imitations exist with regard to transfusions : People with type A blood can only receive type A and type O blood; People with type B blood can only receive type B and type O blood; People with type AB blood can receive type A, B, AB and O blood; Because people with type AB blood can receive any of the other types, they are called universal recipients ; People with blood type O can only receive type O blood; As people who have type O blood can donate blood to any of the other types, they are called universal donors . Taking the presence of the rhesus factor into account, the following limitations exist in transfusions : People with Rh+ blood can only receive Rh+ blood; People with Rh- blood can only receive Rh- blood. What types of blood transfusions are there? There are various types of blood transfusions and blood components. They are therefore prescribed i n accordance with the individual characteristics of each person and their specific situation. For blood components, there are transfusions of red blood cells, platelets and plasma . Isolated transfusions of white blood cells are not carried out. Red blood cell transfusion Red blood cell transfusions are used in people who do not have enough red blood cells. Without these cells, the blood does not have the capacity to transport oxygen in sufficient quantities to maintain the functioning of the various organs. A substantial loss of red blood cells may occur in the following circumstances: Accidents; During or after surgery; Any abundant bleeding. Some diseases lead to the destruction of red blood cells. Therefore, red blood cell transfusion may be necessary: During or after surgery; During or after giving birth; For the victims of accidents; For the treatment of anaemia of various causes; For the treatment of other diseases that interfere with the number and/or function of these cells. Platelet transfusion Platelet transfusions may be used in patients with active bleeding or who are at risk of bleeding , either because they have few platelets or because the function of these cells is impaired. Plasma transfusion Plasma transfusions provide proteins that are important for coagulation to take place and may therefore also be necessary in situations where there is haemorrhaging. Plasma transfusion is therefore used to help control bleeding and to treat autoimmune diseases . Are there any alternatives to blood transfusion? Yes. These alternatives include: Administration of minerals or hormones that stimulate the bone marrow to produce cells; Treatment of the cause of the problem that has led to the need for a transfusion. However, the effects obtained in this way are not immediate , and can take weeks or even months. Therefore, these alternatives are not the best option in situations of sudden blood loss. What is autologous transfusion? In situations where surgery is scheduled in the medium term (at least 4 to 6 weeks away), an autologous transfusion or self-transfusion is possible -the patient receives their own blood or blood component. In these cases, blood is taken from the patient which may, after the correct processing and storage, be used during or after their surgery if necessary. Blood collected for autologous transfusions cannot be used in other patients . If it is not needed, it will be disposed of . What are the risks and complications of blood transfusion? Receiving blood in Portugal is safe and associated with a low rate of risk or complications . The risks of transfusion are: HIV infection (1 in 4,700,000 transfusions); Hepatitis C (1 in 82,000 transfusions); Development of antibodies and immune reactions; Bacterial contamination; Respiratory distress related to antibodies in donor blood; Temporary reduction of natural immunity. Reactions to transfusions can sometimes happen. They are usually mild and temporary , arising from the patient’s antibodies reacting to the blood product, and there is specific treatment provided. Very rarely (1 in 250,000 cases of reactions) they can be fatal. This article was written with the support of physicians and other clinical professionals from the Hospital da Luz network . The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
