PRODUCTS USED FOR BLOOD TRANSFUSION

In clinical practice, whole blood, its components and products may be used.

Whole blood. Certain precautions are necessary in checking donor and blood for transfusion. No donor should be used who has a haemoglobin value below 12 g/l or who has a history of syphilis, malaria, viral hepatitis, chronic allergy, drug sensitivity or HIV infection. The donor's serologic test for syphilis and the test for antiHBsAg and HIV antibodies should be negative. Do Rh typing on both donor and recipient and check recipient's serum for unusual antigens. Cross-match blood. Blood for transfusion is drawn into containers with ACD (acid-citrate-dextrose), CDP (citrate-dextrose-phosphate), or CDPA-1 (citrate-dextrose-phosphate-adenine) anticoagulant (1: 4), which binds calcium ions, prevents blood from coagulating and thus markedly prolongs the viability of red blood cells. Salts of EDTA and heparin may also be used as anticoagulants. Apart from the anticoagulant, the product contains antibiotics and glucose.

The blood must be stored at 4-6 °C. Properly stored blood may be used for transfusion until 21 days (with ACD) or 35 days (with CDPA) after withdrawal from the donor. Blood should not be used after the expire date.

It is noteworthy that not all the functions of the preserved blood are equally maintained. The most vulnerable are the haemostatic factors and immunity, whereas the oxygen-binding ability remains operable for a longer period. Therefore, when bleeding arrest is required, it is recommended that the blood be obtained at least 2-3 days prior to transfusion, and for the purpose of immune correction at least 5-7 days.

Freshly citrated blood. 6% sodium citrate is used as anticoagulant in the ratio of 1: 10. Such blood should be used immediately or within some a few hours after withdrawal.

Heparinised blood. It is used to fill in the artificial circulation machine. This requires large amounts of blood that is why citrated blood is dangerous as it may result in citrate intoxication. Heparin, glucose and chloramphenicol are used as the preservative. Heparinised blood can be stored at 4 °C for only 24 hours.

Blood components. Components of blood have been widely used due to the significant incidence of complications associated with the transfusion of whole blood. Moreover, the therapeutic effect of blood component transfusion is higher since it acts directly on specific bodily functions. This type of transfusion is indicated in chronic anaemia and bleeding (packed red blood cells); in leucopenia and particularly in agranulocytosis and immune deficiency (granulocyte concentrates); in thrombocytopenia (platelet concentrates); in hypoor dysproteinaemia, coagulation disorders, deficient blood circulatory volume (liquid, frozen or dried plasma, albumin, protein). In addition, component transfusion is cost-effective, i.e. higher therapeutic effect is achieved with lesser amounts of blood products.

Red blood cell products are obtained from whole blood, which is either left to stand or centrifuged for separation of plasma. They differ from donated blood in the minimal content of plasma and high concentration of red blood cells (haematocrit 0, 65-0, 8 l/l); they are stored in bottles or plastic bags at 4-6 °C for 21 days.

Packed red cells. Sodium citrate is used as the preservative. These are stored at 4-6 °C for 8 - 15 days and indicated for bleeding, anaemia and other blood diseases, and sepsis.

Washed and frozen red blood cells are the preparations of red cells suspended in saline, produced by for three to five-fold cell separation.

Freezing can be done either gradually (in electro-freezers at -70-80 °C) or rapidly (using liquid nitrogen at -196 °C). Frozen red blood cells can be stored for 8-10 years. To thaw the red blood cells, the container is put into water bath heated to as high as 45 °C and is then washed. Red blood cells can be stored at 4 °C for maximum one day after thawing.

The advantage of frozen red blood cells is that they contain minimum, if at all, undesirable antigens (free haemoglobin, leucocytes, platelets), clotting factors, potassium, serotonin. These are, therefore, indicated for allergies, post-transfusion reactions, cardiac or renal insufficiency, thrombosis and embolism. The blood of a universal donor can be used to avoid massive transfusion syndrome. Washed native or frozen red blood cells are used for patients with HLA incompatibility or those sensitised to plasma proteins.

Platelet concentrates are prepared either from whole donated blood by centrifugation or by plateletpheresis of single donors' blood using cell separators. They may be stored at 4-22 °C for up to 7-9 days; it is, however, advisable to use them freshly prepared within 24 hours. The indications include bleeding in patients with thrombocytopenia of different origin (blood disorders, post-radiation conditions, chemotherapy, as well as haemorrhage resulting from massive transfusions for profuse bleeding, disseminated intravascular coagulopathy). Transfusing platelet concentrates one has to take into account the ABO and Rh system compatibility, and to perform the biological testing since the platelet products may contain residuals of donor's red blood cells.

Granulocyte concentrates are preparations comprising mainly leucocytes with traces of red blood cells, platelets and plasma. These are usually collected from HLA-matched donors by cell separation, or leucopheresis, and stored in bottles or plastic bags at 4-6 °C for maximum 24 hours. Again, transfusing white blood cells the physician will take into consideration the ABO, Rh system compatibility. It is a must to perform the biological test for compatibility. The granulocyte concentrates are used for patients with neutropenia, particularly in agranulocytosis resulting from radiation, chemotherapy, and severe sepsis. Post-transfusion reactions involve dyspnoea, rigors, fever, tachycardia and hypotension.

Blood plasma is obtained by means of separation of blood. It contains protein and other essential components (enzymes, vitamins, hormones, antibodies). Liquid plasma should be used ex tempore, within 2-3 hours after its collection; plasma is collected into 50-250 ml bottles or plastic bags. It may also be used previously frozen or dried (lyophilised). Frozen plasma should be stored for 90 days at -25 °C or for 30 days at 10 °C. Before use it has to be thawed at 37-38 °C. Any suspensions, a change in colour (e.g. greyish-red discolouration), unpleasant smell or evidence of turbidity found before transfusion all preclude its application.

Plasma is indicated for replacement of blood circulating volume (massive whole blood loss, i.e. blood loss exceeding 25% of blood volume, in combination with whole blood and red cell products), bleeding arrest (in haemophilia) and parenteral nutrition (in burns, sepsis). It is contraindicated for severe allergies.

The usual dose is 100-500 ml or even 500-1, 000 ml in shock. Group compatibility (ABO) of the donor and recipient is taken into account and biological testing performed.

Dry plasma is available in 100, 250 or 500 ml bottles and stored for 5 years. Prior to its use it will be dissolved in distilled water or normal saline. Indications for use are similar to those of liquid and frozen plasma, except that dry plasma is ineffective if used for bleeding control. Biological test is a prerequisite.

Albumin. It is prepared through separating plasma and subsequent pasteurising and contains 5, 10 or 20 g of protein (97% albumin) in a 100 ml solution. Its 5, 10 and 20% solutions are available in 50, 100, 250 or 500 ml bottles. A high oncotic activity accounts for its ability to keep water within the body and hence increase the circulating blood volume.

It is therefore indicated for shock of whatever origin, burns, hypoproteinaemia in oncological patients, debilitating and chronic infections, as well as plasmopheresis.

Combined with blood transfusion and red blood cell products, albumin works more efficiently in blood loss and post-haemorrhagic anaemia. Transfusion of albumin is indicated for hypoalbuminaemia, with the level of albumin being 25g/l. The dosage of the preparation is as follows: 300-500 ml (5%); 200-300 ml (10%); 100-200 ml (20%) and the like. The usual rate of its infusion is 40-60 drops/minute while in shock it may be given in bolus. Biological testing helps prevent anaphylaxis, which, if severe, is a relative contraindication for transfusion of albumin.

Protein is prepared either from plasma or blood serum. It consists of albumin (75-80%) and a and b globulins (20-25%). The product usually contains 40-50 g/l of protein. Therapeutically, protein is similar to plasma. Pasteurised, i.e. free of hepatitis viruses, protein is available in 250-500 ml bottles. The daily dose for patients with hypoproteinaemia is 250-500 ml of the solution. The preparation is given for several days. For severe shock and massive blood loss the dose is increased to as high as 1, 500 - 2, 000 ml. It is mandatory to give protein with either donated blood or red cell products. The rate of its infusion depends on the patient's condition: usually infused slowly it is given in bolus for shock and hypotension.

Cryoprecipitate is obtained by allowing the frozen plasma from a single donation to thaw at 4-8 °C and removing supernatant. It is stored at 0 °C in 15 ml vial. Cryoprecipitate contains factor VIII: C, or antihaemophilic globulin, factor XII, or fibrin-stabilizing, or von Willebrand factor (vWF), and fibrinogen. The preparation is indicated for patients with defective blood coagulation secondary to a decrease in VIII factor levels (haemophilia A and Willebrand's disease).

Prothrombin complex is prepared from blood plasma and distinguished by high concentrations of factors II, VII, IX, and X. The preparation is administered to arrest or prevent bleeding in patients with haemophilia B, hypoproteinaemia, and hypoproconvertinaemia.

Fibrinogen is obtained from plasma. Its preparations are indicated for congenital and acquired hypoor afibrinoginaemia, as well as intractable bleeding.

Prepared from plasma, thrombin contains thrombin, thromboplastin and calcium chloride, and is stored in vials in powdered form. It is used for capillary and parenchymal bleeding, and extensive wounds.

Apart from the above-mentioned preparations, immunologically active preparations are also prepared from the donated blood - g globulin (staphylococcal, tetanus and varicella immune globulins).

Complex immune preparations (e.g. sandobulin) are obtained from plasma donated by people who have had the disease and therefore acquired the immunity, and those vaccinated against the disease. The preparations contain high titres of antibodies. These are stored in vials and given either intramuscularly or intravenously as indicated.

BLOOD GROUPING

The antigen components of human blood are numerous. To date, about 500 cellular antigens that are the components of blood, as well as above 40 combinations of antigen systems have been identified. In practical transfusiology, the ABO and Rhesus factor (Rh) systems are regarded as the most important.

I. With standard isohaemagglutination serum For the blood grouping the following are required:

• two sets of standard sera I (0), II (A), III (B) of different serial groups;

• an ampoule of serum IV (AB) (Put a dry clean pipette into each ampoule that contains the serum! );

• a vial with normal saline and a pipette;

• a clean dry plate;

• a ground slide;

• sterile spear-like needles for finger pricks;

• sterile swabs;

• alcohol.

The procedure has to be performed in a well-lit room at 15-25 °C.

Each vial of the standard serum has to be labelled with information of the blood group, serial number, titre, expiry date, and the manufacturer. Never use vials without the relevant information provided.

A standard serum ampoule for blood (ABO system) grouping is normally supplied with a specific colour indicator: I (0) - colourless (no stripes on the label), II (A) - blue (two stripes on the label), III (B) - red (three stripes on the label), IV (AB) - yellow (four stripes on the label). The ampoule with serum is kept at 4...10 °C, the sera being clear. The ampoule should be intact.

Never use for transfusion the serum that contains flakes, sediments or turbidity. The typing serum should be potent, with a titre of at least 1: 32 and the first signs of agglutination being evident within 30 seconds. Expired serum may never be used.

Procedure. Divide the plate into 4 parts with a colour pencil and label the parts clockwise - I (0), II (A), III (B). Place the serum of the two series of groups I (0), II (A), III (B) on the corresponding areas using their individual pipettes. Cleanse the finger with alcohol and prick it with a sterile needle. Clear away the first blood drop with a swab, while further drops of blood are to be placed with different edges of the slide and thoroughly mixed with a drop of serum (the drop of blood should be 5-10 times as smaller as that of serum). Shaking the plate facilitates mixing the serum and blood. Check initial results in 3 minutes, then add a few drops of normal saline, and shake the plates again to mix the drops again. Examine finally the mixture for agglutination in 5 minutes (fig. 33, colour inset).

In a positive isohaemagglutination reaction, flakes and granulations of red blood cells that have clung together do not separate on dilution with normal saline or shaking. In a negative reaction, drops of serum on the plate, alternatively, appear transparent, evenly coloured pink, with no granules or flakes visible. The four patterns of the agglutination reaction with standard sera of groups I (0), II (A), III (B) are possible:

1. The agglutination reaction is negative with the three sera in both series. The blood under examination is of group l (0).

2. The isohaemaglutination reaction is negative with test serum II (A) in both series and positive with groups I (0) and III (B). The blood under examination is of group II (A).

3. The isohaemaglutination reaction is negative with test serum III (B) in both series and positive with I (0) and II (A) groups. The blood under examination is of group III (B).

4. All the serum of I (0), II (A), III (B) groups give positive reactions to both series of serum. The blood under examination is of group IV (AB).

However, before making the final conclusion another investigation has to be performed with group IV (AB) test serum, following the same procedure as mentioned above. A negative isohaemaglutination reaction following this test attests the blood being of group IV (AB).

If other types of reactions are encountered it means that the procedure was followed improperly.

The information as to the patient's blood group is noted in his/her folder or case history, as well as on the front page of the file with the date and signature of the physician who has conducted the examination.

Mistakes in blood grouping tests are possible when the reaction of agglutination, though having actually occurred, cannot be identified and vice versa.

Agglutination can be overlooked in the following situations:

1) if the strength of the test serum is mild or the red cells are of low agglutinative power;

2) if an excessive amount of blood has been added to the test serum;

3) if the temperature of the room in which the reaction is being performed is too high, a condition which slows down the reaction of agglutination.

To prevent the errors, the test serum to be used should be active in high titres, the ratio of blood to serum being 1: 5-1: 10. The temperature should not exceed 25 °C and the results should be noted in as late as 5 minutes from the beginning of the test.

Agglutination can be erroneously identified due to drying up the serum drop, the arrangement of the red cells into coin-like piles or «cold» agglutination if the test is performed at room temperature below 15 °C. The addition of normal saline to the blood serum drop and performing the test at a temperature above 15 °C eliminates the possibility of such errors. In general, errors in blood grouping almost always result from not following the instructions have not been followed correctly.

In all dubious cases repeat the test using test serum of different series and or new standard red blood cells.

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