Acute Reactions

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1. Acute haemolytic reactions

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Acute haemolytic reactions can be classified into two types: immune-mediated or non-immune-mediated.(1)

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Immune-mediated reactions most often occur because of ABO incompatibility between host and donor leading to complement-mediated intravascular haemolysis.(2) These reactions can be very severe. Patients will have fever, hypotension, abdominal pain or chest pain. They may rarely have oozing from the venepuncture site, which would indicate Disseminated intravascular coagulopathy (DIC), a rare but potentially fatal complication.

 

Non-ABO antibodies (such as Rhesus, Kell, Duffy) can also cause immune-mediated haemolytic reactions. However, these are less severe typically resulting in extravascular haemolysis and reduced lifespan of transfused cells.(2)

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Non-immune-mediated reactions occur because of red blood cells having been damaged prior to transfusion resulting in haemoglobinaemia or haemoglobinuria. These do not usually cause significant clinical symptoms.(2)

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2. Allergic reactions

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Some patients may experience allergic reactions during a transfusion. These typically present as rash, pruritus or urticaria. Allergic reactions are IgE-mediated and occur because of recipient hypersensitivity to transfused blood components such as plasma proteins, proteins on white blood cells or platelets.(1) This can be managed using Chlorphenamine, which is an antihistamine. It can be given either intravenously or orally. 

 

3. Anaphylaxis

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Rarely, patients may experience severe anaphylaxis as a result of transfusion. Clinical signs of anaphylaxis include bronchospasm, cyanosis, hypotension and soft tissue swelling. This is a medical emergency.

 

The ABCDE (Airway, Breathing, Circulation, Disability, Exposure) approach should be used and senior support should be sought. Management includes giving supplemental oxygen and manoeuvres to keep the airway patent. Adrenaline 500 micrograms IM should be given to relieve the bronchospasm and for vasoconstriction. 0.9% NaCl should be given to maintain blood pressure. Other drugs that can help are IV hydrocortisone and Chlorphenamine.(1)

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4. Bacterial contamination

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Bacterial contamination of blood products could occur when blood was collected from the donor (if bacteria were present in his/her bloodstream), when blood was being processed (if sterile procedures were not strictly adhered to) or when blood was being transfused (if aseptic technique was not adhered to during cannulation).

 

Patients may present with fever, hypotension and rigors. If bacterial contamination is suspected, blood and urine cultures should be sent off urgently and broad-spectrum antibiotics may be required.(3)

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5. Transfusion related acute lung injury (TRALI)

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TRALI occurs when HLA antigens in the donor react with neutrophil antigens in the recipient, resulting in neutrophil-mediated inflammation in the recipient’s lungs. This causes pulmonary capillaries to become more leaky resulting in pulmonary oedema (without the patient being in a state of fluid overload).(2)

 

Patients may complain of dyspnoea and cough and a chest X ray may be needed. TRALI should be treated as Acute Respiratory Distress Syndrome (ARDS) and patients may need Oxygen.

 

If a TRALI reaction is reported, the donor should be removed from the donor panel.

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6. Transfusion associated circulatory overload (TACO)

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Transfusions can sometimes lead to circulatory overload (acute hypervolaemia), especially in elderly patients or those with pre-existing cardiac failure. Hypervolaemia results in acute pulmonary oedema and patients will typically present with dyspnoea, hypoxia, tachycardia, raised JVP and bibasal crackles on auscultation. Oxygen therapy and a diuretic (eg: Furosemide) may be required.(3)

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7. Non-haemolytic febrile transfusion reaction (NHFTR)

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These reactions are usually caused by cytokines released from white blood cells in donor blood. Patients present with fever and shivering within an hour of starting the transfusion. Non-haemolytic febrile transfusion reactions are a diagnosis of exclusion as haemolytic and septic reactions (both of which are much more serious) can present in a similar manner.

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Delayed Reactions

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1. Delayed haemolytic transfusion reactions (DHTR)

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These occur in patients receiving regular transfusions. After receiving a transfusion, over the next 3 months some patients produce antibodies against the foreign red cells. These antibodies may be at a very low level and may not be detected in pre-transfusion testing. However, when they receive their next blood transfusion, these antibodies detect the foreign red cells. The body increases production of these antibodies over the next 7-10 days and this leads to extravascular haemolysis of the transfused red blood cells.(2)

 

Delayed haemolytic reactions are a particular problem for patients with sickle cell anaemia as they often require frequent blood transfusions.