What is blood transfusion?
Blood transfusion is a life saving measure in which blood from a blood bag is transferred into the vein of a recipient. Care and survival of patients brought in emergency situations such as natural disasters, road accidents and gun-shots would be impossible without blood transfusions. Patients may also require transfusions associated with treatment of conditions like thalassaemia, chemotherapy for cancer or bone marrow transplant.
Where does the blood come from?
A normal adult has about 5 litres of blood in his body and can safely donate 10% of it. Blood banks conduct blood donation drives where healthy individuals between 18-60 years are invited to donate a part of their blood (350ml or 450ml depending on the donor’s weight). Proper care is taken in selecting a donor. The medical history is taken and the prospective donor is examined for any ailments. The blood then collected is also screened for infectious agents such as Hepatitis B, C and HIV.
Blood groups and Rh factor
Before the blood can be given to a patient, its blood group is determined. An individual may have A, B, AB or O blood group and Rh positive or negative, making a total of eight groups, eg. A Rh positive, A Rh negative and so on. The donor blood should have a blood group that matches with the patient’s blood.
Is blood transfusion safe?
Strict screening practices should be adopted in the selection of blood donors. Their medical history is taken and blood is checked for HIV and other such infections before it is administered. The storing and processing also has to be carefully monitored. Whole blood can be stored for a limited time only but its various components can be frozen and stored for a year or longer.
A technique called haemapheresis is used wherein only a desired blood component is taken from the donor’s blood and the remaining fluid and blood cells are immediately transfused back into the donor. This technique allows the collection of large amounts of a particular component, such as platelets, from a single donor. Blood for transfusion must be taken only from blood banks that are certified by the Ministry of Health, Government of India. Most major hospitals have such certified blood banks.
What are the various blood components that can be transfused?
- Red blood cells: These cells give red colour to the blood. They carry oxygen from the lungs to the body tissues and take carbon dioxide back to the lungs. They are administered in cases of anaemias resulting from kidney failures, gastrointestinal bleeding and acute blood loss resulting from trauma.
- Platelets: These are cell fragments in the blood responsible for stopping bleeding. They are given in the treatment of decreased platelet counts associated with chemotherapy or a condition called thrombocytopaenia.
- Plasma: It consists of 90% water and 10% plasma proteins. It is given in case of clotting disorders.
- White blood cells or leukocytes: They are the disease-fighting cells in the blood. They are given in cases of infections unresponsive to antibiotics.
How is blood transfused?
When a patient requires a blood transfusion, a small volume (3ml-5ml) of his blood is sent to a blood bank. There it is grouped for ABO and Rh and it is cross-matched with the stored donor blood of the same group. If the donor blood matches the patient’s blood, it is considered suitable for transfusion.
A patient receives a blood transfusion through a superficial vein of the forearm or the upper surface of the hand. A transfusion set, which consists of a fine needle attached by a plastic tubing to a drip chamber with a filter, is connected to the blood bag. The blood or blood component is given as a steady slow drip and one transfusion generally takes 3-4 hours to complete.
What is a blood transfusion reaction?
This is a complication of blood transfusion in which there is an immune response against the transfused blood cells. Transfusion of blood between compatible groups causes no problem. Blood transfusion between incompatible groups causes an immune response against the cells that carry the antigen, resulting in transfusion reaction. The immune system of the recipient attacks the donated blood cells, causing them to break. Serious symptoms such as kidney failure and shock may occur. Other symptoms may include fever, rash, blood in the urine and dizziness.
What are the risks involved?
Blood transfusion carries certain risks. Some patients may not tolerate the blood of another individual, inspite of it being matched and may have a transfusion reaction. This may manifest as fever, chills, breathlessness, a drop in blood pressure and even collapse. Blood transfusion may also transmit infections like hepatitis B, C, or HIV despite the blood being screened. This is because no test can detect all infections or provide absolutely safe blood. It is important that blood transfusions be given only when absolutely necessary. When used judiciously, its benefits far outweigh the risks.