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HMS Homeostasis I > Transfusion Medicine > Flashcards

Flashcards in Transfusion Medicine Deck (40)
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1
Q

Preservatives added to blood when it is donated

A

CPD-adenine:

Citrate chelates calcium to prevent clotting

Phosphate acts as a buffer to maintain the pH within physiologic range

Dextrose provides a source of food for the red cells during storage

Adenine enhances cell viability

2
Q

Fractionation of blood donations

A
3
Q

Effects of removing WBCs from blood donations

A
  • Prevents graft vs host disease (this risk can be further reduces by irradiation)
  • Prevents MHC reactions (remember, all the other blood cells are not nucleated and so don’t have MHC)
  • Reduces risk of CMV infection
4
Q

ABO antigens

A
5
Q

ABO antigens reside on ___.

A

ABO antigens reside on band 3.

6
Q

Rh positive and Rh negative refer to the presence or absence of ___.

A

Rh positive and Rh negative refer to the presence or absence of the Rh D antigen.

7
Q

Important distinction between ABO and Rh D reactions

A

The ABO reaction is via IgM and involves the fixation of complement, leading to intravascular hemolysis

The Rh D reaction is via IgG and does not involve complement, but rather results in opsonization-mediated phagocytosis, leading to extravascular hemolysis

8
Q

Most cases of autoimmune hemolysis due to warm IgG antibodies are caused by . . .

A

. . . autoantibodies against the Rh antigens

9
Q

Principal mode of testing for blood antigens

A

standardized antibody-based agglutination assays, similar to Coomb’s test

10
Q

Sample transfusion blood test result table

A
11
Q

Indications for transfusion

A
  • Postural hypotension (strongly suggests hypovolemia)
  • Anemia due to intracorpuscular hemolysis
    *
12
Q

In patients with renal failure, ___ should be a preferred treatment over transfusion.

A

In patients with renal failure, EPO supplementation should be a preferred treatment over transfusion.

13
Q

In patients with anemia due to non-genetic production problems, before jumping to transfusion, ___ should be attempted

A

In patients with anemia due to non-genetic production problems, before jumping to transfusion, addressing the cause of the production problem should be attempted

This goes for: Loss of EPO production, nutritional anemias, anemias secondary to solvable disease processes

14
Q

Evidence-based hemoglobin threshold for transfusion

A

A hemoglobin level of 7 to 8 g/dL has been found to be appropriate.

Take other factors into consideration, such as carbon monoxide status for smokers

15
Q

Cases where you should be a bit more lenient with transfusions

A

Patients with anemia who begin to experience angina

Patients with genetic production problems that have shown evidence of poor compensation

16
Q

One ‘unit’ of blood

A

525 mL

17
Q

The primary indication for platelet transfusion is ____

A

The primary indication for platelet transfusion is bleeding due either to thrombocytopenia or, much less often, to defective platelet function.

18
Q

Detection of GI blood loss vs platelet count

A

The takeaway here is that there is little or no benefit toward preventing major hemorrhage in transfusing a patient to more than ~10,000 platelets per microliter.

19
Q

The primary indication for transfusion of fresh frozen plasma is . . .

A

The primary indication for transfusion of fresh frozen plasma is correction of deficiencies of multiple clotting factors, as may occur in liver disease, overdosing of warfarin, and disseminated intravascular coagulation

20
Q

Infusions of plasma for hemorrhage

A

Infusion of fresh frozen plasma may be beneficial following acute massive hemorrhage because it restores both lost colloid (principally albumin), which helps to expand intravascular volume, and clotting factors.

21
Q

Cryoprecipitate

A

The protein precipitate from plasma that forms at 4oC

Contains factor VIII, von Willebrand factor, factor XIII, and fibrinogen

Currently, cryoprecipitate is primarily used for treatment of hypofibrinogenemia.

22
Q

Immediate hemolytic reactions are nearly always due to ___

A

Immediate hemolytic reactions are nearly always due to ABO incompatibility

23
Q

Symptoms of acute transfusion rejection

A
  • Fever
  • Chills
  • Dyspnea
  • Tachycardia
  • Hemoglobinuria
  • Severe pain, usually in lower back
  • For large transfusions, hypotensive shock, oliguria, and disseminated intravascular coagulation may be precipitated
24
Q

Many of the symptoms of acute transfusion rejection are likely to be missed ____

A

Many of the symptoms of acute transfusion rejection are likely to be missed if the patient is under general anesthesia

With the exception of hypotension

25
Q

At the first signal that incompatible blood may have been administered, . . .

A

. . . the infusion must be stopped, the identity of the patient and unit must be reconfirmed, and serologic testing repeated on the donor and recipient blood.

26
Q

Acute vs delayed transfusion rxn

A
27
Q

Patients develop alloantibodies to protein antigens in foreign blood only . . .

A

Patients develop alloantibodies to protein antigens in foreign blood only after pregnancy or transfusions.

28
Q

Treating delayed transfusion reactions

A

Delayed hemolytic transfusion reactions usually do not require therapy.

Rather, just take extra steps to ensure that the next transfusion is a better match.

29
Q

Timecourse of delayed transfusion reaction

A
30
Q

Hemolytic disease of the fetus and newborn

A

Involves an immunologic response following the “transfusion” of red cells from the fetus into the maternal circulation. Maternal Rh D alloimmunization is by far most common. Similar to delayed transfusion reaction.

31
Q

Scenario for most cases of HDFN

A
  • Father Rh+
  • Mother Rh-
  • Child inherits Rh+ from dad
  • Mother becomes immunized but first pregnancy otherwise asymptomatic
  • Next child also inherits Rh+ from dad
  • This time the mother produces more antibody, which crosses into fetal circulation via FcRn
  • The fetus develops a severe hemoltyic anemia from mom’s antibodies, with hydrops and generalized tissue hypoxia
  • Unconjugated-bilirubin from hemolysis can also cause irreversible brain damage to infant
32
Q

Treating HDFN

A

If suspected in third trimester, an intrauterine transfusion may be performed to alleviate symptoms.

33
Q

Preventing HDFN

A

HDFN is rarely encountered today thanks to the discovery 50 years ago that the administration of anti-D immunoglobulin (RhoGAM) to Rh-negative mothers after their first delivery safely and effectively suppresses sensitization to Rh D and prevents the development of HDFN in subsequent pregnancies.

34
Q

Transfusion-related lung injury

A

Acute interstitial pneumonitis that appears within 6 hours of transfusion, accompanied by dyspnea, tachycardia, hypoxemia, fever, and hypotension.

Thought to be due to donor antibodies binding and activating host neutrophils or pulmonary endothelial cells.

Most common cause of transfusion-related death

35
Q

Treating TRALI

A

Primarily supportive

  • Oxygen
  • Mechanical ventilation
  • Resolution in 48-96 hours
    *
36
Q

Preventing TRALI

A

Use of male serum reduces risk, as anti-HLA antibodies are thought to mediate many cases, and women who have been pregnant are more likely to be sensitized against HLA.

Cases of suspected TRALI are investigated by the blood bank. Donors of blood products believed to have caused TRALI are permanently banned from donating blood.

37
Q

Infectious risks from transfusion

A
38
Q

Transfusion risk summary

A
39
Q

ABO antigens are ___ while Rh antigens are ___.

A

ABO antigens are carbohydrate while Rh antigens are protein

40
Q

“Crossmatch” test

A

Donor’s erythrocytes

Patient’s plasma

Look for agglutination