Indications Elective transfusion - Correction of anemia before surgery - In preparation for major surgery Emergency transfusion - Hemorrhage
Blood Grouping More than 400 antigen systems have been identified. Expressed on red cell membranes. Such antigens capable of interacting with serum antibodies in recipient. HOWEVER, only a small proportion have potential to cause clinically significant hemolysis.
ABO system System of sugar residue antigens. MOST IMPORTANT ANTIGEN SYSTEM WHY? IgM Presence of naturally occuringIgM antibodies in the serum
They occur spontaneously. Are directed against A and/or B antigens that the individual’s own red cells do not carry. Can cause fatal reactions by causing lysis of incompatible red cells within intravascular compartment.
Rhesus system Antibodies are IgG type. These are induced antibodies and not naturally occuring. Require a past exposure to cause reactions e.g. Previous blood transfusions or exposure to fetal red cells during pregnancy.
Mainly cause red cell destruction in RE system i.e. Extra vascular hemolysis. Consists of 47 antigens. c, C, D, e and E are most important. Rh positive = D antigen present Rh negative = Absent D antigen
Other blood group systems Many other systems Most likely to be implicated in hemolytic transfusion reactions are
Cross-matching Blood routinely grouped according to ABO and Rhesus systems. After matching donor and recipient blood groups, cross matching is done. Donor RBC are incubated with recipient’s serum to look for evidence of hemolysis
Physiology of stored blood Several metabolic and functional changes occur. Easily compensated by an individual with moderate hepatic, renal or bone marrow function. Blood is stored at 4-8 C mixed with anticoagulant, most commonly CPD-A (citrate-phosphate-dextrose-adenine).
Red cell changes Depletion of ATP and 2,3 DPG. RBC become rigid and less effective in oxygen delivery to tissues. White cell and platelet changes No useful function in blood stored for more than 24 hrs. Coagulation factors V, VIII and XI fall in 24 hrs IX and X become ineffective in 7 days.
Biochemical changes Becomes acidotic Becomes hyperkalemic Due to spontaneous red cell lysis Readily compensated except in seriously compromised patients and massive transfusion. Microaggregates Granulocyte –platelet aggregates start to form within 24 hrs of storage. Can form pulmonary microemboli . Thus BT set should have an appropriate filter.
Whole blood and component therapy
Whole blood Fresh whole blood Rich in all blood elements including coagulating factors. Stored whole blood Looses many properties as explained. CPD-A blood can be stored at 4-8 C for 35 days CPD blood for 21 days
Whole blood(contd.) Indication - Acute , active blood loss with hypovolaemia - Exchange transfusion Contraindication - Riskof volume overload : Chronic anaemia Incipient cardiac failure 1 unit increases Hb by about 1.4 g/dl
Packed red cells
Units with red blood cells and some plasma
With anticoagulant like CPD-A
Hematocrit is 75% to 80%
- Replacement of red cells in anaemic patients. - Use with crystalloid or colloid solution in acute blood loss. Dosage 10 - 15 ml / kg
Fresh frozen plasma Contains approx. 200 ml of plasma. Frozen within hours to preserve the level of coagulation factors. Stored at -40 C, has a shelf life of 6 months. Should be thawed for 30 minutes in waterbath before admi. To be given within 30 min after thawing.
FFP(contd.) Indications Coagulopathieseg. Due to liver disease. DIC
Cryoprecipitate Prepared from FFP by thawing and separating and refreezing jelly like precipitate. Enriched with factor VIII, Fibronectin and Fibrinogen. Volume is about 20 ml. Indicated in patients with Hemophillia, uncontrollable hemmorhage and DIC.
Platelet concentrates Each unit of platelets are suspended in 30-50 ml of plasma . 5 to 6 such units are combined to make a ‘Pool of platelets’ to raise platelet count by atleast 30 x 10⁹/l in a 70 kg man. The only blood product not kept refrigerated, stored at 22 C under gentle agitation. Shelf life is less than 5 days. Indicated in DIC, Dengue fever, Bone marrow failure.
Transfusion reactions(Hazards of transfusion) ‘Reaction’ = ‘Any unwanted effect of blood transfusion’ Doctor should always be sure that transfusion is absolutely necessary and consider alternatives. Upto 1 L of blood loss can safely be restored with crystalloids alone if bleeding has stopped .
1. Immediate and life threatening Profound intravascular haemolysis, Air embolism, Circulatory overload, Complications of massive blood transfusion.
2. Immediate but not life threatening Severe extravascularhemolysis, Febrile reactions, Atopic reactions.
3. Late reactions Delayed immune mediated hemolysis Local reactions Transmission of infection
Hemolytic reactions Fortunately rare Cause = transfusion of mismatched blood due to clerical or technical error. Always check labels on blood bags as well as patients blood group before starting transfusion. Signs and symptoms Pain at infusion site Shortness of breath Chest pain Facial flushing, vomiting Fever and rigors
Hemolytic reactions(contd.) Patient may go for shock, renal failure, DIC and jaundice. Rx Stop transfusion immediately Maintain venous access and saline infusion Injchlorpheniramine 10 mg iv given stat Steroids Insert urinary catheter Management of complications
Febrile reactions and minor allergic reactions Nonhemolytic febrile reactions and minor allergic reactions are the most common transfusion reactions. Each occurring in 3-4% of all transfusions. Nonspecific symptoms of fever, chills, and malaise. Rx Stop transfusion Inj CPM 10 mg iv Send to lab for re-crossmatching
Complications of massive blood transfusion Massive transfusion is defined as the replacement of more than one-half of the blood volume within a 24-hour period . Or replacement of 10 units of blood over the course of a few hours .