What is blood Transfusion?
Blood transfusion refers to the process of receiving blood or blood components into one’s circulation intravenously.These component of blood are Red blood cells,Plasma,Platelets,Clotting factors and White blood cells
Reasons for blood transfusion
Basically some cases may be to save by
- Replacing the blood lost during medical intervention such as surgery
- Replacing a deficiency of specific blood components such as platelets (thrombocytes) ,the red blood cells (erythrocytes), and clotting factors such as fibrinogen,prothrombin,ionized calcium ( Ca++ ) etc
- To Increase the oxygen-carrying capacity of the haemoglobin in blood, as in the case of anaemia.
- To increase the intravascular volume in shock caused by bleeding.
Normally, The blood is collected from donors in containers that contains anticoagulants which prevent the blood from clotting. The most common anticoagulant used in blood bags are a mixture of sodium citrate, citric acid and dextrose (acid citrate dextrose – ACD), (Citrate Phosphate Dextrose Adenine CPDA).
It has the following properties that helps to maintain the quality of the blood
- The sodium citrate prevents clotting.
- The citric acid serves as a preservative
- Dextrose (Source of Energy) prolongs the lifespan of the red blood cells (erythrocytes).
- Heparin is also used as an anticoagulant in blood that is to be transfused within 24 hours of collection.
- Adenine used for the preservation of whole blood and red blood cells for up to 35 days
Heparinized blood is necessary for extracorporeal shunts (as in open heart surgery). The heparin is less damaging to platelets and to the enzyme: 2,3-diphosphoglycerate (DPG), which promotes the release of oxygen from oxyhaemoglobin.
Blood grouping before blood transfusion
A number of laboratory tests must be completed before blood or blood products can be transfused in order to avoid blood related hazard. This tests includes
- Determination of compactibility by crossmatch.
- Screening for antibodies that may produce adverse effects if transfused.
- Screening for possible infectious agents that could be transmitted with transfusions
- Hemoglobin level
- Blood pressure etc
The following tests are mandatory on all units of blood collected for transfusion:
- Determination of the ABO group and Rh type of both donor and receptor
- Screening for blood-group antibodies
- Hepatitis B
- Hepatitis C
- Syphilis (Treponema pallidum
- West Nile virus
- Chagas disease (Trypanosoma cruzi)
Screening for HBV,Syphilis,HIV,HCV before blood transfusion
If, and only if, all of these markers are negative can blood be conveyed to the Blood Bank for storage until usage. In case of positive results for some of these tests,this may prevent further donation by that person.
Not all laboratory may provide all these tests but the main aim is to limit blood transfusion hazard.
Potential donors may be screened by questionnaire regarding travel to endemic areas or contact with persons at risk or about their lifestyle.
Dilemma during Blood transfusion
In some tropical countries,Patient suffering with some bacteria infection are able to donate blood when they are the only possible source to save life of the receptor in critical need of blood transfusion.
For example , If a patient is in urgent need of blood group “O” Rhesus negative and the only donor in that location is infected with some sort of bacteria (Bacteraemia) infections such as syphilis,gonorrhoea or chlamydia,This donor can still donate blood provided the receptor will be kept under antibiotics as soon as possible in order to deal with the bacteria infection.
Some laboratory even turn to transfuse HIV infected blood when there are no other possibility of getting uninfected blood.This is to save life meanwhile the receptor will be strictly kept on Anti-retroviral medication.
All of these involve medical or ethical dilemma and of course this also demand patient consentment before any procedure is to be carried out to avoid breaching the autonomy of the patient.
What to write on a blood bag after blood collection
After blood collection,the blood bag is labeled clearly to indicate
- Donor number
- Donor name,
- Blood group and Rhesus whether Rh positive or negative,
- Anticoagulant used (CPDA-1,ACD)
- The day of collection and expiry date.
The blood may be transfused as whole blood (containing all the components) or some of the components may be separated out for administration to meet the specific need of treatment while avoiding massive blood transfusion.This will depends on what was requested by the physician.
Storage of blood and shelf life
Blood is stored at a temperature of 2-4oC and has a Shelf life of
- whole blood / red cells in CPD/CP2D of 21 days
- CPDA has a shelf life of 35 days
- Additive (AS1, AS3, AS5) is 42 days.
Types of Blood components used in blood transfusion
Plasma bags, taken from blood donations, are pictured at the Interregional Transfusion CRS in Bern, Switzerland, June 15, 2017. REUTERS/Denis Balibouse – RC1CFC22E050
- Whole blood: It is administered to replace blood loss or to increase the intravascular volume in shock caused by haemorrhage.
- Packed red cells: this type of blood component is gotten by removing a large portion of the plasma from whole blood by centrifugation. The remaining cells are then given to increase the oxygen carrying capacity of the recipients blood. The advantage of transfusion of packed cells is that lesser volume is added to the patients intravascular volume, hence, preventing the risk of circulatory overload. The cells may be transfused in a small volume of normal saline or plasma.
- Platelets (Thrombocytes): platelets may be concentrated and transfused in small volume to avoid the administration of a large volume of fluid. This avoids the risk of overloading the recipients heart and the circulatory system. Transfusion of platelets is used to control bleeding in patients with thrombocytopenia (low platelets in the blood). ABO compatibility is not essential but the development of alloimmunization is a complication of platelet transfusions. The rate of platelet destruction is increased in the sensitized individual. Rh immunoglobulin is administered to Rh negative persons who receive platelets from an Rh-positive donor to prevent Rh sensitization.
- White blood cells (Granulocytes): White blood cells from an ABO compatible donor are prepared from the whole blood by a process called Leukapheresis. They are administered to neutropenic (low white blood cells in the blood) patients with persistent infection despite antibiotic therapy.
- Albumin: this is an important protein in the blood and it is prepared from plasma and is available in concentrations of 5% and 25% solutions. It is used to rapidly expand plasma volume in severe hypovolaemia (low intravascular volume). This is expensive.
- Clotting factors: concentrates of certain clotting factors such as factors VIII and IX are also prepared from fresh frozen plasma to control bleeding in haemophilia A and B or in fibrinogen deficiency. Preparations include cryoprecipitates and specific factor preparations.
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