What is Blood? Blood is composed of a pale yellow fluid called Plasma in which are suspended red cells ( erythrocytes), white cells ( leukocytes) and platelets ( thrombocytes).Blood has important functions such as:
- Transportation and distribution of nutrients and waste product.
- Regulatory functions
- Body defence.
There are four major blood types which are blood type A, B, AB and O.
WHAT DO YOU UNDERSTAND BY BLOOD TRANSFUSION?
This is the process of transferring blood or blood product from one person into the circulatory system of another. It can be obtained by bleeding healthy male and female donors into suitable containers with the right anticoagulant. There are three types of donors namely:
- Voluntary donor which can be from friends
- Relative donors which are relations of the person requiring transfusion
- Commercial donors are donors that donate for money which should be discouraged because there is a significantly higher risk of transmitting infection when the donor is paid and most of them can donate often than is recommended.
Blood transfusion should be voluntary i.e. with no financial reward because the desire for money may make donors not to reveal all their medical history or their life style.
CRITERIA FOR RECRUITMENT AS A BLOOD DONOR
- Age: Donors should not be less than 18 years or more than 65 years.
- Donors are not bled more than twice in one year to protect them from iron deficiency
- Weight of the person: Person weighing 45-50kg or more can safely donate 450ml of blood.
- Medical history of the prospective donor should be known
- Heamoglobin Values: Should not be less than 13.5g/dl for males and not less than 12.5g/dl for females.
- Persons likely to suffer from ill effect of donation should not donate e.g. fainting.
- Prospective donors who received a recent vaccination (within weeks) are not allowed to donate blood to avoid the transmission of living viruses.
- Temperature of the person must not be raised to exclude any febrile disease e.g malaria
- Measurement of blood pressure; A donor should not have an abnormal low blood pressure or a high blood pressure.
MAJOR BLOOD TRANSMITTED INFECTIOUS AGENT TO SCREEN FOR BEFORE DONATION
- Human immunodeficiency Virus (HIV) 1 and 2
- Hepatitis B Virus (HBV)
- Hepatitis C Virus( HCV)
- Treponema pallidum ( agent of syphilis)
- Plasmodium species ( agents of malaria)
- Trypanosoma species
TYPES OF BLOOD TRANSFUSION
- Direct transfusion: This is elective transfusion of blood to a patient with the blood donated by his family member or friend.
- Autologous Transfusion: Is the use of patients own blood or blood products for the patients transfusion. The patient’s blood is preferred because the hazards of immunization of disease do not arise.
CONTRAINDICATION TO AUTOLOGOUS TRANSFUSION
Patients in the following categories should not be permitted to enlist for autologous transfusion:
- Those who suffers from some form of active infection because storage profuse bacteria proliferation in the stored blood.
- Patients who were already anaemic before the commencement of surgery.
- Those who may not need much blood.
- Age and fitness as applicable to blood donors should also apply to autologous blood transfusion.
- Pregnant women should be excluded from autologous transfusion.
REASONS FOR BLOOD TRANSFUSION
- Blood Transfusion may be necessary to restore or maintain the oxygen carrying capacity of blood. It is best achieved by transfusing Packed red cell.
- Maintenance of blood volume: In cases of acute blood loss e.g. post- operative massive bleeding or bleeding after injury; transfusion of whole blood or plasma gives good result.
- Maintenance of haemostasis: It sometimes necessary to replace coagulation factors to maintain haemostasis.Various blood components may be transfused as the situation demands e.g. platelet concentrate, fresh frozen plasma, cryoprecipitate and factor V111 and 1X concentrates
- Restoration of Leucocytes function: The clinical condition demanding transfusion of leucocytes do not arise very often, but may be necessary in a granulocytopenic patient with infection.
USE OF BLOOD COMPONENT,DERIVATIVES AND FRACTION
Each component of whole blood such as the formed element proteins and electrolytes has a different and important function to perform .Indiscriminate use of whole blood is not justified when most patients can be effectively be treated with one or more of the component.
Blood components are prepared from a single blood donation by simple physical separation methods e.g. by centrifugation using plastic bags. The component separated can then be transferred into other blood bags, stored and transfused individually, avoiding contamination.
I. Whole blood: Contains red cells, platelets, and leucocyte, plasma proteins used for treating cases of acute blood loss e.g. surgical severe gastrointestinal or uterine haemorrhage.
II. Packed red cell: This is a unit of blood from one donor from which the plasma has been removed following sedimentation or centrifugation. It is the treatment of choice in chronically anaemic patients to correct anaemia and to raise the oxygen transportation of the red cells.
III. Leucocytes-poor blood: This is the whole blood from which most leucocytes has been removed by centrifugation, filteration and washing. Prepared for patient who as a result of multiple transfusions have developed antibodies to leucocytes or for patients undergoing renal or bone marrow transplants for which those leucocytes antigens are contraindicated.
IV. Platelet-rich plasma, Platelet concentrate: Platelet transfusion is helpful in patients with serious thrombocytopenia due to the failure of the bone marrow to produce viable cells. Thrombocytopenia may be found in patients suffering from acute leukaemia.
V. Fresh Frozen Plasma: It contains all the coagulation factors present in fresh plasma .Used mostly in replacement of coagulation factors. The plasma so obtained is rapidly frozen in order to secure the labile coagulation factors.
CRYOPRECIPITATE: This is a concentrate of factor V111 prepared from fresh frozen plasma. It contains factor V111, fibrinogen, and vonWillebrand’s factor. Used on haemophilia A patients. It may be useful in DIC and other conditions where the fibrinogen level is very low.
FACTOR V111 AND 1X CONCENTRATES: These are freeze dried preparations of specific coagulation factors prepared from large pools of plasma. They are used for treating patients with haemophilia and vonWillebrand’s disease.
COMPLICATIONS OF BLOOD TRANSFUSION
I. IMMUNOLOGICAL COMPLICATIONS: These incompatible transfusions are caused by technical rather than serological errors, eg wrong labeling of blood, giving out to wrong patient.
II. WRONG PATIENT LABELLING: This often cause most of the incompatible transfusion reaction especially when administered as an emergency. Most cases patients are unconscious and cannot complain of the symptoms and signs of incompatible transfusion. These patients, the other symptoms are hypotension and bleeding which are caused by the release of the products of complement into the plasma causing the contraction of smooth muscles, degranulation of mast cells, there after vasoactive substance are released. The bleeding may be caused by disseminated intravascular coagulation and possibly by the direct activation of the coagulation system by antigen-antibody complexes and by cytokines.
Decreased production of urine may result from incompatible transfusion and may be occasioned by changes in the renal blood flow due to hypotension. Febrile reactions occur also. In cases of Rh (D) incompatibility, fever appears to be the only symptom.
III HAEMOLYTIC TRANSFUSION REACTION: These transfusions are usually due to ABO incompatibility. There is complement activation by the antigen- antibody reaction caused by IgM antibodies leading to rigors, lumbar pain, and hypotension. It can also be due to increased destruction of the transfused red cells usually by IgG antibodies.
IV. NON HAEMOLYTIC (FEBRILE) TRANSFUSION REACTIONS: Febrile reactions are common complications of blood transfusion in patients who have previously be transfused or pregnant. The cause are the presence of leucocytes antibodies in an alloimmunized recipient acting against donor leucocytes in red cell concentrates leading to release of pyrogens; signs are: flushing and tachycardia, fever (>38◦C), chills and rigors.
V. ALLERGIC TRANSFUSION REACTION: Allergic reactions usually appear as urticaria appearing during the transfusion. The skin lesions are pale irregular, slightly raised patches.
STORAGE OF BLOOD
Blood can be safely stored in a gas thermostatically controlled refrigerator of the absorption type providing precautions are taken to ensure the temperature of the refrigerator remains as constant as possible within the range 2-8◦C.Blood is best preserved in CPDA( citrate phosphate dextrose adenine) anticoagulant for 28-35 days storing at a temperature range of 2-8◦C,usually 4◦C.