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Haemolytic Transfusion Reactions (HTR)

You are here : Home/ Blood Bank Zone/ Adverse Reactions to Blood Transfusion/ 2. Haemolytic Transfusion Reactions (HTR)

2. Haemolytic Transfusion Reactions (HTR)

HTR is the occurrence of abnormal destruction of red cells following transfusion. Most of these are due to red cell incompatibility. These reactions can be immediate/delayed or intravascular/extravascular. Intravascular reactions are characterized by destruction of red cells within the blood stream with liberation of haemoglobin into the plasma. Extravascular haemolysis is characterized by phagocytosis of red cells by rnacrophages of the reticulo endothelial system. Acute haemolysis, both intravascular and extravascular, is of major clinical significance.

Immediate haemolytic reactions

A haemolytic transfusion reactions means occurence of signs and symptoms of increased red cell destruction after transfusion. These reactions occur during or withinfew hours of transfusion and may lead to fatal consequences.

Causes

1. Transfusion of ABO incompatible red cells is the commonest cause of these reactions as anti-A and anti-B are strongly haemolytic. Other antibodies associated are anti-Lewis, anti-P and anti-H.
2. Accidental heating/freezing of blood may lead to lysis of red cells.
3. Injection of water into the circulation leading to damage of red cells.
4. Contact of red cells with 5% dextrose in vitro.
5. Bacterial overgrowth may cause lysis of red cells.
6. Red cell abnormality in the patient or donor may precipitate haemolysis after transfusion e.g. G6DP deficiency and paroxysmal nocturnal haemoglobinuria (DNH).

As most ABO incompatible transfusions are due to failure to identify the patient correctly, they are usually given in emergency, intensive care unit or in operation theatres.

Unconsciousness in a patient further increased the risk of transfusion of ABO incompatible blood as no signs and symptoms might call attention to mismatched transfusion being given.

Administration of ABO incompatible blood can be due to :

1. Clerical errors
a. Incorrect labelling
  - recipient�s sample
  - blood bag
  - pilot tubes
  - request form
b. Misidentification of patient at time of collection of sample or transfusoin of blood
c. Mix-up of samples at time of collection.

2. Technical errors
a. Error in blood grouping of donor and recipient samples
b. Error in compatibility testing
- faulty technique
- weak antibodies not detected by routine tests

3. Destruction of recipient red cells by donor antibodies. This occurs due to indiscriminate use of group 0 blood which may contain notent anti-A and anti-B.

Clinical features

Symptoms:-
Chills Flyshing
Chest or back pain	Sweating
Nausea,vomiting	Pain at infusion site
Restlessness	Abdominal discomfort
Signs:
Fever with rigors	Hypotension
Tachycardia	Haemoglobinuria
Dyspnoea	Oliguria
Tachypnoea	Anuria
Pallor	Shock & DIC
Cyanosis

These symptoms are abolished by anaesthetics and modified by morphine. In patients who are in coma or under the influence of drugs during transfusion the only alarming sign may be haemoglobinuria, hypotension or uncontrollable bleeding despite adequate volume replacement.

Any febrile transfusion reaction must be considered and managed as immediate haemolytic transfusion reaction until and unless proved otherwise.

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