74) Blood Transfusion & Blood Substitutes
BLOOD TRANSFUSION –
1.The commonest indication of blood transfusion is during acute haemorrhage be it external or internal.
2.It is indicated during certain major operations, where a good amount of blood loss is inevitable e.g. radical mastectomy abdomino-perineal resection, etc.
3.in case of deep burns blood transfusion is indicated besides initial fluid and plasma Administration, as there is considerable haemolysis and destruction of RBCs.
4.Pre-operatively blood transfusion is required when the patient is already anaemic and there is no adequate time for iron replacement therapy before operation.
5.due to excessive bleeding during operation,
6.when the haemoglobin level is below 10 g/ 100 ml blood transfusion is indicated to treat anaemia. Remembered that in chronic anaemia, it is better to transfuse packed cells rather than whole blood to reduce more burden to the already burdened heart due to hypervolaemia.
7.malnutrition and hypoproteinaemia, blood transfusion is
8. certain cogulation disorders like haemophilia, Christmas disease, thrombocytopenic purpura etc, blood transfusions or blood fraction transfusions are required.
10.During chemotherapy for malignant diseases blood transfusion is often indicated
COMPLICATIONS OF BLOOD TRANSFUSION-
A. Transfusion reactions and
B. Transmission of diseases.
A. Transfusion reactions-
1. INCOMPATIBILITY- There are there causes of incompatibility
(i) Incompatible transfusion
(ii) Transfusion of blood which is already haemolysed by heating or over freezing or shaking.
(iii) Transfusion of blood after expiry date.
4.SENSITISATION TO LEUCOCYTES AND PLATELETS
B. Transmission of diseases
1. SERUM HEPATITIS-
2. ACQUIRED IMMUNE DEFICIENCY SYNDROME (AIDS)
3. BACTERIAL INFECTIONS
C. Reactions caused by massive transfusion-
1. ACID-BASE IMBALANCE
3. CITRATE TOXICITY
5. FAILURE OF COAGULATION- the most important danger of massive transfusion is the failure of natural process of coagulation. This is mainly caused by two factors
E. (a) thrombophlebitis
(b) air embolism, etc.
BLOOD SUBSTITUTES – The blood substitutes can be basically divided into 2 groups –
A. plasma and its derivatives and
B. Synthetically prepared various solutions.
A. PLASMA AND ITS DERIVATIVES
1. Plasma- If the whole blood is kept sometime, a sediment will form at the bottom of the container. The upper clear portion is the plasma and the blood sediment is the packed red cells.
Fresh frozen plasma- Plasma removed from fresh blood, which is obtained within 4 hours, is rapidly frozen by immersing solid corbon dioxide and alcohol mixture. Stored at- 20º C. This process preserves all the coagulation factors, particularly factors V and VIII. Plasma is very useful in the treatment of coagulation deficiencies, in liver disease, in haemophilia (factor VIII deficiency), in Christmas disease (factor IX deficiency) and in defibrination cases. It is also useful in cases of vitamin K deficiency.
2. Platelet rich plasma- This is suitable for transfusion to patients who are suffering from thrombocytopenic purpura.
PLATELET CONCENTRATE- Platelet concentrate is prepared from platelet rich plasma by centrifugation at the rate of 1500 g for 20 minutes. The platelet remains active in vitro for 48 hours. If the platelet concentrate is stored frozen, its effectiveness may be extended to many months of storage.
3. Fibrinogen- It is prepared by organic liquid fractionation of plasma. It is stored in the dried form and before using it is made soluble with distilled water. Such solution is required in cases of severe depletion of fibrinogen e.g. congenital afibrinogenaemia and in disseminated intravascular coagulation (DIC)
4.Albumin- Albumin is prepared by repeated fractionation of plasma by organic liquids then followed by heat treatment. It may be stored for several months in liquid form at 4ºC. main advantage of this is that it is free from the danger of transmission of serum hepatitis. In patients with severe albumin loss e.g. following severe burn ands in nephritic syndrome. Main disadvantage of it is that it is very costly.
5. Cryoprecipitate- the glutinous precipitate is known as cryoprecipitate. It is usually stored at -40º C. it is very rich source of factor VIII. So it is the best treatment of patients with haemophilia (factor VIII deficiency).
B. SYNTHETICALLY PREPARED VARIOUS SOLUTIONS-
1. Dextran- It is polysaccharide polymer with varying molecular weights.
2. Gelatine- Gelatine solutions are among the first used as blood substitutes. This is less effective than dextran as plasma volume expander.
3. Hydroxxethylstarch (HES)- it is made by treating starch with sodium hydroxide ands ethylene oxide.
4. Fluorocarbons- are hydrocarbons in which the hydrogen atoms have been raplaced by fluorine. a colourless, odourless dense liquid, that is chemically inert and poorly soluble.