7.4 Complications of blood transfusions

7.4.1 Hemolytic reaction: 

The donor's red cells are destroyed by the antibodies in the recipient's serum. The cause of this hemolysis is incompatibility of the transfused blood with the patient‘s blood. ABO incompatibility usually produces a violent reaction. The signs of an incompatible blood transfusion may be masked by general anesthesia. The blood pressure and the pulse rate must be checked every 5 minutes for the first 15 minutes after each new bottle of blood. A hemolytic reaction can be produced by just a small quantity of mismatched blood. Human error is frequently involved. Incorrect laboratory work; mislabeling of blood and misreading of the labels on blood bags and bottles, are frequently responsible. Take maximum care in checking the name of the patient, the blood group, the bottle number and expiry date as shown on the blood product, with the slip issued from the laboratory. The patient's name and hospital number on the label of the blood pack should match those on the identification tag worn by the patient. Checking must be done by the anesthetist and another responsible hospital staff member.

7.4.1.1 Signs of incompatible blood transfusion in the anesthetized patient: -Hypotension, tachycardia, cyanosis, skin rash, general oozing from the wound, later jaundice and oliguria (5 - 10% incidence). Acute circulatory collapse (cardiac arrest) and renal failure are the most serious complications and may lead to death. The effects vary with the amount of blood transfused, the degree of incompatibility and the physical state of the patient at the time of transfusion. Signs of incompatible blood transfusion in the conscious patient including feeling of pressure in the head, tingling of limbs, precordial pain, dyspnea, lumbar pain, restlessness, nausea and vomiting, could not be seen in anesthetized patient.

Diagnosis of transfusion reaction is established by hemoglobinuria; send to the laboratory the remaining blood in the bottle or bag, a sample of the patient's blood and sample of the patient's urine.

7.4.1.2 Treatment of a transfusion reaction 

• Stop the transfusion. 
• Treat hypotension appropriately (as for anaphylaxis). 
Give fluids (crystalloid / colloid) 
Give inotropes (e.g. adrenaline, 1-5ml of 1:10,000 solution IV, or dopamine) 
Give other compatible blood, if necessary. 
• Give oxygen 
• Corticosteroids for severe reactions: Hydrocortisone 100-300mg. 
• Establish the diagnosis with blood bank assistance. 
• Treat renal vascular ischemia with: 
Saline, to keep urine output above 1ml/kg/hr (insert urinary catheter). 
Furosemide 20 mg IV 
Mannitol 0.5g/kg IV if available 
• Evaluate and treat disseminated intravascular coagulation: 
Coagulation screen if available (platelet count, activated partial thromboplastin time, fibrinogen). 
Platelet concentrate and fresh frozen plasma as indicated. 
• Manage bronchospasm as for anaphylaxis: 
Adrenaline 1-5ml of 1:10,000 or 0.1-0.5 ml of 1:1000 if necessary. 
Salbutamol 250 - 500 micrograms IV. 
• If patient has rigors and fever with no evidence of haemolysis: 
Start antibiotics 
• Try to distinguish between a transfusion reaction due to incompatible blood and an anaphylactic reaction to another drug. 

7.3.2 Allergic reactions: 

These may be caused by antibodies to white blood cells, platelets or immunoglobulin reactions between patient and donor. Mild urticaria is the commonest manifestation. More serious allergic reactions are: asthma, angioneurotic edema, laryngeal edema, cardiovascular collapse and anaphylactic reaction (rare). Some allergic reactions may be difficult to distinguish at an early stage from hemolytic reactions. 

Treatment 

Mild allergic reactions: give antihistamine e.g. chlorpheniramine 10-20mg IV or promethazine 25 to 50 mg IV. 

Severe reactions: 

• Stop the transfusion 
• Give adrenaline 0.1-0.5mg IV i.e. 0.1- 0.5ml of 1:1000 solution or 1-5ml of 1:10,000 solution (note: the dose of adrenaline should be titrated to effect) 
• Give hydrocortisone 100mg IV and repeat 
• Treat bronchospasm if it occurs. 

7.3.3 Contamination of blood: 

Organisms may enter the blood by contamination through carelessness in collection or cross-matching. They will proliferate if blood is allowed to remain out of the refrigerator at room temperature. Blood that is left out of the refrigerator for more than 30 minutes should not be put back into storage. Some viral diseases may be transmitted in transfused blood especially where screening tests are not available. 

7.3.4 Circulatory over load: 

During rapid transfusions there is always a risk of pulmonary edema and cardiac failure. This is referred to as circulatory overload. This danger is more common in: 

• Elderly patients 
• Patients with severe anaemia 
• Patients with heart disease. 
• Patients receiving massive or large volume transfusions. 

Precautions: Slow the transfusion if the patient's blood pressure is normal. 

Signs of circulatory overload 

• In the conscious patient: dyspnea, cyanosis, engorgement of neck veins, basal crepitation and pulmonary edema. 
• In the anaesthetized patient (many of the above signs will be masked): cyanosis, basal crepitation, reduced lung compliance (stiff lungs), pink frothy secretions in ETT (pulmonary edema) 

Treatment of circulatory overload 

• Stop the transfusion 
• Give oxygen 
• Prop up the patient or raise the head of the table 
• Give diuretics: furosemide 40mg IV. This can be repeated. 
• Give morphine (small doses, i.e. 1-2mg IV) 
• Other measures include the application of tourniquets at a pressure less than the systolic and maintained for 15 minutes at a time. 
• Intermittent positive pressure ventilation with 100% oxygen. 

7.3.5 Citrate intoxication: 

Whole blood is prevented from clotting (after collection), by the use of citrate. The citrate forms a complex with the calcium ions in the blood. Since calcium is necessary for the blood to clot and the calcium is not available (being tied up in a complex with citrate), the blood remains fluid. When the citrated blood is introduced into the patient's circulation, the citrate is quickly broken down into water and carbon dioxide and the calcium is set free. If for some reason the citrate persists in the circulation, signs of citrate intoxication are seen. These signs are essentially the signs of lack of calcium in the blood. 

Signs of citrate intoxication (calcium lack) 

• Cardiac depression- bradycardia and hypotension 
• Increased oozing from the wound 
• Tetany (contraction of facial musculature on tapping the facial nerve) 

Treatment: Give 10ml of 10% calcium gluconate or chloride for every 6 units of blood transfused. 

7.3.6 Hypothermia: 

The rapid administration of large volumes of blood or replacement fluids directly from the refrigerator can result in a significant reduction in body temperature. This can be prevented in the case of large transfusions 

• Put the container of blood or plasma in lukewarm water (if there is no proper warmer) before administering it. 
• The infusion set tubing can be passed through a warm bath or under the warming blanket. 
• Use a blood warmer if available 

7.4.7 Coagulation problems: 

These may be caused by: 

• A reduction in the number of functioning platelets. 
• A reduction in the coagulation factors in old blood. These can both be corrected by giving fresh frozen plasma and platelet concentrate. 
• A reduction in the available calcium, especially in citrate intoxication 
• D.I.C. (disseminated intravascular coagulation) or consumption coagulopathy leading to a fall in platelets and fibrinogen and an increase in fibrin degradation products (FDP). 
•  Depletion of inhibitors of coagulation. 

These problems may begin to occur after 6 (after transfusion of whole blood volume of the patient) units of packed cells or stored blood have been administered. Management explained on the following topics under precaution when transfusing large volume of blood 

7.4.8 Massive transfusion: 

This is defined as the replacement of the total blood volume in less than 24 hours. Coagulation problems commonly result. Platelets and fresh blood or plasma are required. 

Precautions when transfusing large volumes of blood: 

• Use 2 units of fresh frozen plasma for every 6 units of CPD (anticoagulat) bank blood. Fresh frozen plasma contains all the clotting factors except platelets. Where fresh frozen plasma or platelets are not available, fresh blood should be used if possible to provide clotting factors and platelets. 
• Do platelet counts after every 6 units of blood. Give platelets if the count is less than 75,000/ mm3 
• Give calcium gluconate 10% (or chloride) at the rate of 10ml/6 units of bank blood. Give calcium solutions slowly over a period of 5 minutes. If ECG monitoring is available it should be used during calcium administration. 
• Monitor: pulse, blood pressure, ECG, urine output, acid base state and serum electrolytes if possible. 
• Transfuse one unit of blood at a time during transfusion, this helps to recognize which blood is the cause reaction. 

7.4.9 Micro-aggregates 

Are composed of degenerated platelets, White blood cells, fibrin strands denatured proteins, damaged red blood cells (present especially after the first week of storage).

The rate of formation of micro-aggregates depends on length of storage, platelet and WBC count at time of collection and the anticoagulant used. 

Effect of micro-aggregates: They are filtered by the pulmonary circulation and may cause histamine release and pulmonary insufficiency from increased pulmonary resistance and ventilation-perfusion mismatching. These pulmonary micro emboli can be prevented by transfusing blood that is as fresh as possible and by using membrane filters with a small pore size of 20 - 40 microns although this slows the rate of infusion. (Standard blood transfusion sets have a pore size of 170-260 microns).