Ch. 3 - Transfusion reactions

Question 1

How frequent are fatal transfusion reactions?

Answer 1

Generally, 1 in 1-2 million.

Question 2

What are the acute transfusion reactions?

Answer 2

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)

Question 3

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

Answer 3

As little as 5mL.

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

Question 4

What are some symptoms of AHTR?

Answer 4

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

Question 5

What are some possible sources of error resulting in mistransfusion?

Answer 5

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)

Question 6

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

Answer 6

Hemolysis is often exacerbated with transfusion and may mimic AHTR.

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

Question 7

Summarize the pathophysiology of AHTR.

Answer 7

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.

Question 8

What are the laboratory findings in AHTR?

Answer 8

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

Question 9

How is AHTR treated?

Answer 9

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

Question 10

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

Answer 10

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

Question 11

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

Answer 11

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

Question 12

How are allergic transfusion reactions managed?

Answer 12

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

Question 13

How common is FNHTR? What is it caused by?

Answer 13

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

Question 14

What defines FNHTR? What other symptoms may be seen?

Answer 14

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

Question 15

How is FNHTR managed?

Answer 15

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

Question 16

Describe the two types of septic transfusion reactions.

Answer 16

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.

Question 17

Describe the pathophysiology of TRALI.

Answer 17

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

Question 18

What are some risk factors for TRALI?

Answer 18

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

Question 19

How is TRALI managed?

Answer 19

Respiratory support, not diuretics. Most people spontaneously recover.

Question 20

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

Answer 20

Red cell units. (actually, probably platelets)

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

Question 21

Describe the clinical features of TACO.

Answer 21

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

Question 22

What are the delayed transfusion reactions?

Answer 22

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

Question 23

Describe the pathophysiology of delayed hemolytic/serologic transfusion reaction.

Answer 23

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.

Question 24

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

Answer 24

Rh
Kell*
Duffy*
Kidd*** (most common)
MNS
Diego

Question 25

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

Answer 25

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

Question 26

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

Answer 26

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

Question 27

What patients are at risk for TA-GVHD?

Answer 27

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*

Question 28

Describe the pathophysiology of posttransfusion purpura.

Answer 28

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

Question 29

How is posttransfusion purpura managed?

Answer 29

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

Question 30

What are some metabolic aberrations seen in massive transfusion?

Answer 30

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

Question 31

What are the features of hyperhemolytic transfusion reactions?

Answer 31

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

Question 32

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

Answer 32

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.

Question 33

What causes hypotensive transfusion reactions?

Answer 33

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

Question 34

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

Answer 34

Necrotizing enterocolitis

Question 35

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

Answer 35

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