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Book - Transfusion Medicine for Pathologists > Ch. 3 - Transfusion reactions > Flashcards

Ch. 3 - Transfusion reactions Flashcards

1
Q

How frequent are fatal transfusion reactions?

A

Generally, 1 in 1-2 million.

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2
Q

What are the acute transfusion reactions?

A

Acute hemolytic transfusion reaction (AHTR)
Allergic/anaphylactic transfusion reactions
Febrile nonhemolytic transfusion reaction (FNHTR)
Septic transfusion reactions
Transfusion-associated acute lung injury (TRALI)
Transfusion-associated cardiac overload (TACO)

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3
Q

What volume of blood can precipitate an AHTR? What are some non-immune causes?

A

As little as 5mL.

Transfusion with incompatible crystalloid solutions, incorrect storage (old hemolyzed blood?)

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4
Q

What are some symptoms of AHTR?

A 
Fever, chills
Flank pain
Hypotension
Dyspnea
Hemoglobinuria, hemoglobinemia
DIC
ARF
Shock
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5
Q

What are some possible sources of error resulting in mistransfusion?

A 
Wrong blood in tube
Testing wrong sample
Switching of labels
Errors in typing
Grabbing wrong unit
Misidentification of patient or blood product at time of transfusion (most common)
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6
Q

What is the significance of an underlying hemolytic anemia on the incidence of AHTR? Name examples.

A

Hemolysis is often exacerbated with transfusion and may mimic AHTR.

Eg. WAHA, cold hemagglutinin disease, PNH, drug-induced hemolysis

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7
Q

Summarize the pathophysiology of AHTR.

A

IgM antibodies bind and activate complement resulting in red cell lysis. Mast cell mediators are released and clotting pathways are activated. Multiorgan dysfunction (especially renal) sets in.

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8
Q

What are the laboratory findings in AHTR?

A 
Decreased Hb/Hct (below pretransfusion levels)
Hemoglobinemia, hemoglobinuria
Increased LDH, direct bilirubin
Decreased haptoglobin
Abnormal coags (suggestive of DIC)
Schistocytes on peripheral smear.
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9
Q

How is AHTR treated?

A

Supportive therapy using IV fluids and pressors. Management of DIC, maintenance of adequate renal perfusion.

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10
Q

What blood product most often causes allergic transfusion reactions? Why?

A

Platelets. Effects are caused by products from mast cells or basophils which are enriched in platelets.

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11
Q

What are the symptoms of allergic transfusion reaction? What causes anaphylaxis?

A

Urticaria, itching, rash. Anaphylactic reactions are usually due to anti-IgA antibodies.

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12
Q

How are allergic transfusion reactions managed?

A

Treat symptoms (antihistamines, steroids, maybe epinephrine). May premedicate patients with known histories. Mild cases may even continue transfusion.

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13
Q

How common is FNHTR? What is it caused by?

A

1-3% of all transfusion reactions (most common overall). It is caused by passenger cytokines (interleukins and TNFa).

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14
Q

What defines FNHTR? What other symptoms may be seen?

A

Body temperature of greater than 38C with an increase by 1C of more. May have chills or rigors.

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15
Q

How is FNHTR managed?

A

Discontinue transfusion and initiate transfusion workup. Treat with antipyretics. May consider culturing the unit if the fever is severe.

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16
Q

Describe the two types of septic transfusion reactions.

A

Usually platelets contaminated by skin flora (G+ cocci) manifesting with mild response.

RBC units contaminated by transient bacteremias (usually G- rods) which is more often fatal due to endotoxin release.

17
Q

Describe the pathophysiology of TRALI.

A

Anti-HLA or anti-HNA antibodies cause pulmonary sequestration of neutrophils which activate and cause pulmonary endothelial damage.

18
Q

What are some risk factors for TRALI?

A

Liver transplant surgery, alcohol abuse, smoking
Shock
Positive fluid balance
Female sex and increased parity of donor

19
Q

How is TRALI managed?

A

Respiratory support, not diuretics. Most people spontaneously recover.

20
Q

What blood components are most often implicated in TRALI? How common is TRALI?

A

Red cell units. (actually, probably platelets)

TRALI is rare, less than 1 per 100k. Yet, it is the #1 cause of transfusion-related mortality.

21
Q

Describe the clinical features of TACO.

A

Pulmonary edema due to volume overload within a few hours of transfusion. BNP is often highly elevated.

22
Q

What are the delayed transfusion reactions?

A

Delayed hemolytic transfusion reaction
Delayed serologic transfusion reaction
TA-GVHD
Post-transfusion purpura

23
Q

Describe the pathophysiology of delayed hemolytic/serologic transfusion reaction.

A

Patients who have been previously alloimmunized (through transfusion, transplant, or pregnancy) have undetectible antibodies during pretransfusion testing but have a flare of antibodies (sometimes with hemolysis) shortly after receiving an incompatible unit.

24
Q

What blood groups are often implicated in delayed serologic or hemolytic transfusion reactions?

A 
Rh
Kell*
Duffy*
Kidd*** (most common)
MNS
Diego
25
Q

What laboratory findings are seen in delayed hemolytic or serologic transfusion reaction?

A

Spherocytes on peripheral smear. Positive Coombs test with antibody present on elution.

26
Q

What blood matching should patients with sickle cell disease or thalassemia have to reduce the risk of delayed transfusion reactions?

A

Blood should be matched at a minimum for Rh (D/Cc/Ee) and K antigens.

27
Q

What patients are at risk for TA-GVHD?

A

Post-HSCT patients
Patients with T-cell immunodeficiency
Hodgkin lymphoma
Patients on chemo/radiotherapy including purine analogs and anti-lymphocyte therapy.
Fetuses requiring intrauterine transfusion
First-degree relative directed donations

28
Q

Describe the pathophysiology of posttransfusion purpura.

A

HPA-1a negative individuals who h ave been previously alloimmunized destroy HPA-1a positive donor platelets with some bystander destruction of their own platelets.

29
Q

How is posttransfusion purpura managed?

A

IVIG, PLEX, steroids. Future administration of HPA1a-negative platelets.

30
Q

What are some metabolic aberrations seen in massive transfusion?

A

Hypocalcemia (due to citrate)
Hyperkalemia (from storage lesion)
Hypothermia

31
Q

What are the features of hyperhemolytic transfusion reactions?

A

Patients with hemoglobinopathies; may be acute or delayed. Look for marked lab features of hemolysis which worsen with further transfusion.

32
Q

What are the actions taken as part of a transfusion reaction workup?

A
  1. Clerical check of the component (label, paperwork, patient sample)
  2. Repeat ABO testing on a post-transfusion patient sample
  3. Visual check of pre- and post- samples for hemolysis
  4. Coombs test on posttransfusion sample.
33
Q

What causes hypotensive transfusion reactions?

A

Activation of intrinsic contact activation pathway with generation of bradykinin. Worse with ACEi use. May result in tachycardia and gut contraction.

34
Q

What unusual transfusion reaction can be seen in transfusion of preterm and very low birth weight infants?

A

Necrotizing enterocolitis

35
Q

What level of drop in blood pressure is required to diagnose hypotensive transfusion reaction?

A

Drop of either systolic or diastolic blood pressure by 30mmHg or more within 15min of starting the transfusion.

Book - Transfusion Medicine for Pathologists (13 decks)

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