Adverse transfusion reactions

Question 1

What is the definition of an ‘adverse transfusion reaction’?

Answer 1

An ‘adverse transfusion reaction’ refers to any unintended adverse response that occurs in the recipient due to the transfusion of blood, blood component, or plasma-derived product.

Question 2

What are the strategies to minimize the risk of transfusion reactions?

Answer 2

Careful donor selection and screening
Keep the collection system closed
Proper storage of blood products
Avoid using expired or abnormal-looking products
Blood typing and A/B type matching
Cross matching when appropriate
Infusing blood products into a dedicated intravenous line
Passing all blood products through a blood filter
Administering an appropriate volume and rate
Using appropriate infusion and fluid warming devices

Question 3

How can adverse transfusion reactions be classified?

Answer 3

Adverse transfusion reactions can be classified based on their time frame in relation to the transfusion and the involvement of the immune system.

Question 4

What is the distinction between non-immunological and immunological transfusion reactions?

Answer 4

Non-immunological: No immune system involvement, often caused by physical effects of blood or its components.
Immunological: Involves an antigen-antibody mediated response in the recipient.

Question 5

Define Acute Haemolytic Transfusion Reactions (AHTRs).

Answer 5

AHTRs involve accelerated destruction of red blood cells due to preformed recipient antibodies or, in cats, natural antibodies in donated plasma. They can be acute or delayed and may be immunologic or non-immunologic.

Question 6

What are the clinical consequences of immune responses in AHTRs?

Answer 6

Clinical consequences include signs of significant immune activation, release of histamine and inflammatory mediators, hemoglobinuria, hemoglobinaemia, icterus, and coagulopathies. Acute kidney injury and shock may also occur.

Question 7

How can the risk of AHTRs be reduced?

Answer 7

The best way to minimize the risk is through appropriate compatibility testing, including blood typing the recipient and donor, type matching, and conducting major and minor cross matches

Question 8

Define Delayed Haemolytic Transfusion Reactions (DHTRs).

Answer 8

DHTRs occur 24 hours to 28 days after blood product administration and are often a secondary response involving pre-existing recipient antibodies.

Question 9

What are the diagnostic criteria for Delayed Haemolytic Transfusion Reactions (DHTRs)?

Answer 9

DHTRs are diagnosed when there’s an unexplained decrease in PCV or hemoglobin and at least two indicators of red blood cell destruction within 24 hours to 28 days after transfusion. Evidence of red blood cell alloantibodies must also be present.

Question 10

What is the timeframe for acute transfusion reactions, and how do they differ from delayed reactions?

Answer 10

Acute transfusion reactions occur during or within 24 hours of the transfusion, and they are typically more serious than delayed reactions, which can have lifelong consequences for the recipient.

Question 11

How can immune-mediated reactions be minimized, and what are the strategies involved?

Answer 11

Blood typing, cross matching, and leukoreduction of units are strategies to minimize the risk of immune-mediated reactions. However, the risk cannot be completely eliminated.

Question 12

What is the incidence of febrile non-haemolytic transfusion reactions (FNHTR), and what are their common clinical features?

Answer 12

In dogs and cats, the incidence of FNHTR ranges from 1.3-24.2% and 3.7-22.9%, respectively. Clinical features include an increase in body temperature, typically caused by leucocytes in the donated product or the presence of inflammatory cytokines.

Question 13

What are the potential causes of FNHTR, and how is it diagnosed?

Answer 13

Potential causes include recipient leucocyte antibodies and cytokine release during product storage. FNHTR is diagnosed by excluding other potential reactions, and specific criteria include a recipient’s body temperature >39°C, increasing by >1°C during or within 4 hours of the transfusion.

Question 14

How is FNHTR managed, and what is the recommended approach?

Answer 14

FNHTR management involves stopping the transfusion immediately. There is no specific treatment, and the decision to restart the transfusion depends on the clinical status of the recipient. Leucoreduction can reduce the incidence of FNHTR.

Question 15

What is transfusion-related acute lung injury (TRALI), and what are its pathophysiological mechanisms?

Answer 15

TRALI is characterized by non-cardiogenic pulmonary edema resulting from interactions between recipient neutrophils and the pulmonary endothelium. The pathophysiology involves activated neutrophils adhering to endothelium, releasing cytotoxic enzymes and reactive oxygen species, causing lung injury.

Question 16

What are the proposed mechanisms of neutrophil activation in TRALI, and what biological agents can induce it?

Answer 16

Neutrophil activation in TRALI involves priming and subsequent activation. Priming can be caused by cytokines released from dying endothelial cells, stimulated endothelial cells, lipids from degraded membranes, other white blood cells, or infectious agents.

Question 17

How is TRALI recognized and diagnosed in human recipients, and what are its signs?

Answer 17

In humans, TRALI signs include dyspnea, tachycardia, hypoxemia, cyanosis, fever, cough, and hypotension. Diagnosis involves acute hypoxemia, radiographic evidence of bilateral pulmonary edema, no signs of cardiac failure, and no pre-existing lung pathology.

Question 18

What is the management approach for TRALI, and what diagnostics are recommended?

Answer 18

TRALI management includes stopping the transfusion, assessing vital signs, providing oxygen therapy, minimizing stress, and implementing mechanical ventilation if necessary. Diagnostics involve measuring oxygen saturation, arterial blood gas analysis, and thoracic radiographs.

Question 19

What is the typical timeframe for acute transfusion reactions to occur?

Answer 19

Acute transfusion reactions occur during or within 24 hours of the transfusion of blood or plasma-derived products.

Question 20

What are the two possible causes of febrile non-haemolytic transfusion reactions (FNHTR)?

Answer 20

FNHTR can result from recipient leucocyte antibodies or cytokine release during product storage.

Question 21

How are cytokines involved in febrile non-haemolytic transfusion reactions (FNHTR)?

Answer 21

Cytokines released from leucocytes and platelets during storage can cause pyrexia, a key feature of FNHTR.

Question 22

What is the main strategy to reduce the incidence of FNHTR in humans?

Answer 22

Pre-storage leucoreduction, achieved by passing the product through a specialized filter, is effective in reducing the incidence of FNHTR in humans.

Question 23

What is the most common cause of morbidity and mortality in human transfusion recipients?

Answer 23

Transfusion-related acute lung injury (TRALI) is the most common cause of morbidity and mortality in human transfusion recipients.

Question 24

What is the proposed mechanism behind TRALI?

Answer 24

TRALI occurs due to a complex interaction between recipient neutrophils and the pulmonary endothelium, resulting in interstitial and alveolar edema.

Question 25

What are some clinical signs of TRALI in humans?

Answer 25

clinical signs of TRALI in humans include dyspnoea, tachycardia, hypoxaemia, fever, and non-productive cough.

Question 26

What are the main signs of an allergic transfusion reaction in veterinary patients?

Answer 26

Allergic transfusion reactions in veterinary patients may present with urticaria, erythema, pruritis, angioedema, and vomiting.

Question 27

What is the primary mediator responsible for the effects in an allergic response?

Answer 27

Histamine is the primary mediator responsible for various effects in an allergic response, including vasodilation, bronchospasm, and pruritis.

Question 28

How is transfusion-associated circulatory overload (TACO) recognized?

Answer 28

Clinical signs of TACO include hypoxia, tachypnea, increased respiratory effort, jugular vein distension, and radiographic evidence of pulmonary infiltrates.

Question 29

What is the definition of Transfusion Transmitted Infections (TTIs)?

Answer 29

TTIs result from the transfusion of blood or blood components containing infectious, pathogenic organisms, originating from either the donor or exogenous contaminants during collection, processing, preparation, or administration.

Question 30

What are the two sources of organisms causing TTIs?

Answer 30

The sources are the blood donor during collection and exogenous contaminants during collection, processing, preparation, or administration.

Question 31

What are the factors influencing the risk of TTI transmission?

Answer 31

Factors include the capability of asymptomatic infection, resistance to cold storage, carrier state development, viral load, stage of infection, replicative capacity, pre-existing immunity, transfused component, presence of donor antibody, recipient’s resistance, and immunosuppression.

Question 32

How can the risk of TTIs be reduced in veterinary donors?

Answer 32

By implementing donor eligibility criteria, reviewing medical history, conducting physical examinations, and screening for infectious diseases, including vaccination, prophylactic parasite treatments, travel history, and veterinary health checks

Question 33

What types of infections are capable of being transmitted by blood transfusion?

Answer 33

Viruses, prions, bacteria, protozoa, and hematological parasites.

Question 34

What are examples of transfusion-transmitted infections in veterinary recipients?

Answer 34

In dogs, parvovirus through human plasma, and in cats, feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV).

Question 35

What are the criteria used to determine if a Transfusion Transmitted Infection (TTI) exists?

Answer 35

Presence of laboratory evidence of the pathogen in the transfused blood product, evidence in the donor at the time of donation, evidence in an additional component from the same donation, or evidence in an additional recipient of a component from the same donation. Plus, no other potential exposure to the pathogen.

Question 36

What are potential sources of contamination leading to Transfusion-Associated Sepsis?

Answer 36

Contamination can occur during blood collection, component manufacture, preparation, or administration. Common sources include the donor’s skin, blood collection systems, cotton wall balls, and water bath during plasma defrosting.

Question 37

What are indicators of concern with platelet units indicating potential bacterial contamination?

Answer 37

Discoloration, bubbling, absence of a platelet swirl, and platelet clumping.

Question 38

What is Post-Transfusion Purpura, and what causes it?

Answer 38

Post-Transfusion Purpura is a rare platelet disorder occurring 5-12 days after a platelet transfusion. It results from exposure to a platelet antigen in the transfused product, leading to the production of platelet antibodies and subsequent destruction of recipient’s platelets.

Question 39

What defines a massive transfusion, and how is it related to citrate toxicity?

Answer 39

A massive transfusion occurs when a patient receives a red cell product equal to or greater than their total blood volume in 24 hours, or 50% of their total blood volume in three hours, or four units of red cells within one hour with the anticipation of further transfusion support. Massive transfusions can lead to citrate toxicity.

Question 40

How does citrate function as an anticoagulant, and what is its metabolism influenced by?

Answer 40

Citrate chelates with ionized calcium, preventing coagulation. Metabolism occurs mainly in the liver, with additional metabolism in the kidneys and skeletal muscle. In conditions like massive transfusions, hepatic overload or low cardiac output can overwhelm citrate clearance.

Question 41

What are the clinical signs of hypocalcemia associated with citrate toxicity?

Answer 41

Clinical signs include panting, restlessness, weakness, facial pawing/rubbing, twitching, trembling, shaking, seizures, and vomiting. Signs are related to abnormal muscle activity, including myocardial depression, leading to hypotension.

Question 42

What is the QTc, and how is it relevant in diagnosing citrate toxicity?

Answer 42

The QTc (corrected QT interval) represents the time for ventricular depolarization and repolarization. In citrate toxicity, prolonged QTc, observed on electrocardiography, indicates hypocalcemia. Normal QTc for dogs is 150-240 ms, and for cats, it’s 70-200 ms.

Question 43

How is citrate toxicity definitively diagnosed according to AVHTM?

Answer 43

Diagnosis requires the recipient to have impaired hepatic function, receive a massive transfusion, experience a drop in ionized calcium below 0.7 mmol/L, and display signs consistent with hypocalcemia.

Question 44

What is the recommended management for citrate toxicity, and how can it be prevented?

Answer 44

Management involves stopping the transfusion, providing calcium supplementation, and monitoring for resolution of signs. Prevention includes identifying at-risk recipients, regularly monitoring ionized calcium in massive transfusions, and considering red cell washing.

Question 45

What is a Hypotensive Transfusion Reaction (HYTR), and what is its pathogenesis?

Answer 45

HYTR is a sudden decrease in blood pressure during or after a transfusion. Pathogenesis involves elevated bradykinin levels, causing vasodilation. It’s associated with whole blood or packed red blood cell transfusions.

Question 46

How is HYTR recognized and diagnosed?

Answer 46

HYTR responds rapidly to transfusion discontinuation, systolic blood pressure drops by at least 30 mmHg, and it usually resolves within 30 minutes. Monitoring arterial blood pressure helps detect HYTR.

Question 47

What is the proposed mechanism for Acute Pain Transfusion Reaction, and how is it diagnosed?

Answer 47

Acute Pain Transfusion Reaction is poorly understood, involving severe pain in the lower back, joints, or chest. Proposed mechanisms include spasm induced by free hemoglobin, volume overload, or cytokines. It’s diagnosed after excluding other reactions and accounts for new-onset severe pain during or after transfusion.

Question 48

What parameters are recommended for monitoring during a transfusion, and what additional monitoring is suggested?

Answer 48

Recommended parameters include mentation, mucous membrane color, respiratory rate, pulse rate, temperature, and arterial blood pressure. Additional monitoring should include pain, pulse oximetry, physical assessment, and lung auscultation during respiratory assessment.

Question 49

What investigations should be performed in the event of an unexpected acute transfusion reaction?

Answer 49

Verify species and blood product.
Confirm blood type compatibility.
Check blood product expiry date.
Ensure product acceptance criteria are met.
Review preparation, defrosting, and warming procedures.
Assess haemolysis level in red cell products.
Conduct a major or minor cross match.
Perform Gram staining and culture of the blood smear from the unit.
Culture both the unit and a post-transfusion blood sample from the recipient.

Question 50

Why is reporting adverse reactions important, and what benefits does it offer?

Answer 50

Reporting adverse reactions enables data collection for comparison of reaction incidence, identification of associations between reactions and products, and evaluation of reaction reduction strategies. It drives evidence-based practices, research, and improvement in transfusion safety.

Question 51

What is haemovigilance, and what is its goal in the context of transfusion?

Answer 51

Haemovigilance encompasses adverse event surveillance across the entire transfusion chain. The goal is to protect donors and recipients, proactively identify safety concerns, and implement strategies to reduce or mitigate any risks associated with blood transfusion.

Question 52

Define a “near miss” in the context of transfusion.

Answer 52

A near miss occurs when there is a deviation from standard procedure or policy that could result in an unsafe or incorrect transfusion. Importantly, this deviation is detected before the actual transfusion takes place.

Question 53

What is SHOT, and what aspects of the transfusion process does it cover in its reporting system?

Answer 53

SHOT (Serious Hazards of Transfusion) is a UK haemovigilance reporting system. It covers recruitment/screening, donation, care of donors, testing/QC, storage, processing, administration, monitoring, and reporting in its reporting categories.

Question 54

How does SHOT define a serious reaction or event in the context of transfusion?

Answer 54

A serious reaction or event is an unintended response that has the potential to cause fatality, be life-threatening, disabling, incapacitating, prolong hospitalization, or result in morbidity.

Question 55

What types of errors and events does SHOT’s annual report typically highlight in transfusion practices?

Answer 55

SHOT’s annual report may include data on incorrect blood component transfusion, avoidable, delayed, or over transfusion, handling and storage errors, and instances of right blood to the right patient.

Question 56

What is the purpose of veterinary haemovigilance, and how does it differ from human haemovigilance?

Answer 56

Veterinary haemovigilance aims to enhance transfusion safety by systematically monitoring and reporting adverse reactions. In a published case, a veterinary institution implemented a haemovigilance program focusing on adverse transfusion reactions, distinguishing itself from human haemovigilance.

Question 57

How was the veterinary haemovigilance program developed, and what were its aims?

Answer 57

The program was developed by a multi-disciplinary clinical team, defining criteria for adverse reactions, imputability levels, and grading. Its aims were to systematically report and analyze adverse transfusion reactions.

Question 58

What was the outcome of the veterinary haemovigilance program, and how did it impact transfusion practices?

Answer 58

Over 718 canine and 124 feline transfusions, 32 confirmed transfusion reactions were reported. Data from haemovigilance led to the introduction of leucoreduction filters, replacement of an older blood storage fridge, implementation of haemolysis checks, and additional transfusion training for the clinical team