255/256 - Blood Transfusions

Question 1

If a patient is acutely bleeding, what is “priority #1” to replace?

Answer 1

IV blood volume; use fluids

Goal is to avoid hypovolemia, hypoperfusion

Question 2

Which of these infections is most frequently transmitted by blood transfusions?

1. HCV
2. HBV
3. HIV
4. Bacterial sepsis (platelets)
5. West Nile virus

Answer 2

d. Bacterial sepsis (platelets)

Question 3

A 72-year-old patient with metastatic breast cancer on chemotherapy is emergently transferred to your hospital with vertebral collapse and thoracic spinal cord compression. The neurosurgery service recommends immediate surgery. Her Hgb is 8.4 gm/dL, platelet count 55K/uL, PT 15.6 sec (normal 10-13) (INR 1.4), PTT 38.2 sec (normal 25-35), fibrinogen 160 mg/dL (normal 200-400).

Which blood component would be your highest priority for transfusion before surgery?

1. None needed
2. RBCs
3. Platelets
4. Plasma
5. Cryoprecipitate

Answer 3

c. Platelets
* I think it’s this but not toally sure*
* Threshold to give RBCs: Hgb < 7 g/dL (<8 g/dL in cardiac issue)*
* Threshold to gibe plasma: INR > 1.7 (or PTT >1.5x normal)*
* Threshold to give cryoprecipitate: Fibrinogen <100 (<200 obstetric)*

Question 4

What is the highset infectious-disease risk from transfusions?

(Result and type of transfusion)

Answer 4

Bacterial sepsis from platelets

Question 5

What is the normal immediate response to platelet transfusion?

What constitutes a refractory response?

Answer 5

Normal = platelets rise by 25-30k

Refractory = platelets rise by <10k

Question 6

1 dose of cryoprecipitate increases a patient’s fibrinogen level by how much…

on average?

Ideally?

Answer 6

Average: 40 mg/dL increase in fibrinogen

(if not consumed)

Ideally: 65 mg/dL

Question 7

For which blood products (2) do we have pathogen inactivation methods?

Answer 7

Plasma

Platelets

Still in development for RBCs

Question 8

What is the goal of giving cryoprecipitate to a patient?

Answer 8

Increase fibrinogen levels

Question 9

List 4 key initial manifestations of transfusion reaction

Answer 9

Fever

Rash

Hypotension

Respiratory problems

Question 10

What is the goal fibrinogen when you are giving cryoprecipitate?

(How do you know when you’re done?)

Answer 10

>100 mg/dL in pts with bleeding or surgery

>200 mg/dL in obstetric pts

Question 11

Which element of RBC compatibility testing is most critical?

Answer 11

ABO

Question 12

What causes graft vs. host disease?

What is the treatment?

Answer 12

Donor lymphocytes attack host tissues

Pts does not ahve a normal rejection response to the transfused RBCs

Most commoni in pts who are severely immunosupressed, or when there is very close HLA-matching

Recipient WBCs see donor RBCs as self and does not attack them, but the donor WBCs see recipient antigens and attack them

Treat with corticosteroids

Question 13

1 unit of RBCs will increase a patient’s hemoglobin by how much?

Answer 13

1 g/dL

Question 14

A 27-year-old motorcyclist suffers multiple injuries in a collision and is in trauma surgery. He has diffuse bleeding in the surgical fields and his plasma fibrinogen is 70 mg/dL despite numerous units of plasma. With an ideal response, how many doses of cryoprecipitate are needed to achieve the recommended fibrinogen level?

1. None—no cryo needed
2. One
3. Two
4. Five

Answer 14

b. One
* Ideal response = 40 mg/dL increase, target is >100 mg/dL*

Question 15

The blood bank places a transfusion tag on each unit containing patient’s ID and unit number. Which one of the following pre-transfusion blood checks provides the most complete patient safety?

1. Check the transfusion tag patient ID with the patient wristband ID
2. Verify the transfusion tag unit # with the blood bag unit #.
3. Compare the transfusion tag patient ID and unit # with the blood unit # and the patient wristband ID.
4. Read the patient her name from the transfusion tag and her wristband

Answer 15

c. Compare the transfusion tag patient ID and unit # with the blood unit # and the patient wristband ID

Question 16

What is the effect of plasma transfusion on INR?

Answer 16

Will normalize INR a bit if its really high

If INR is only moderately elevated, INR won’t do much

Question 17

Which patients are at highest risk of an anaphylactic transfusion reaction?

Answer 17

Patients with selective IgA deficiency

Question 18

Describe the pathogenesis of acute hemolytic transfusion reaction

Answer 18

Host antibodies to donor ABO antigens (ABO incompatibility)

Can also be caused by host antibodies to non-ABO antigens in donor blood (missed in screening)

RBCs lyse -> membranes damage kidneys, activate clotting

RBC-antibody immune complexes activate inflammation

Question 19

1 unit of plasma increased a patient’s plasma clotting factor levels by…

Answer 19

<6 percentage points

Question 20

Describe the pathogenesis of anaphylactic transfusion reaction

Answer 20

Pre-formed host antibodies to donor plasma proteins

Vs. acute hemolytic, where host antibodies are to donor RBC antigens

Most common in patients with selective IgA deficiency

Tx: antihistamines, epinephrine, corticosteroids

Question 21

Which preventive or therapeutic measure is incorrect for the adverse event shown?

1. Acetaminophen for febrile reaction
2. Leukoreduction for graft-vs-host disease
3. Male plasma for transfusion-related acute lung injury
4. Blood bank records for delayed hemolytic reaction

Answer 21

c. Male plasma for transfusion-related acute lung injury
* Give respiratory support; there is no TRALI-specific therapy*

Question 22

What is the hemoglobin threshold for transfusion?

Answer 22

7 g/dL

(8 g/dL in acute carediac disease or thrombocytpenia pts)

Question 23

What is the treatment for transfusion-related lung injury?

Answer 23

Respiratory support

• There is no specific treatment*
• Caused by antibodies in donor plasma that attack host WBCs*

Question 24

Which patients are at highest risk of having RBC antibodies?

Answer 24

Anyone who has been in contact with someone else’s blood

• People who have been pregnant
• People who have recieved blood transfusions

But 1-2% of patients who have not been pregnant or recieved a transfusion will have RBC alloantibodies

Question 25

What is the treatment for acute hemolytic transfusion reaction? (4)

Answer 25

Diuresis

Plasma, platelets as needed for bleeding

Blood pressure support

Compatible RBCs if necessary

Caused by host antibodies to donor RBCs

Question 26

What are the thresholds for giving plasma in a patient who is bleeding or about to undergo a procedure?

• PT:
• PTT:

Answer 26

• PT: INR > 1.7
• PTT: >1.5x normal PTT

Question 27

What is the universal plasma group?

Answer 27

AB

• Does not have anti-A or anti-B antibodies
• Opposite of universal RBC group*

Question 28

Describe the pathogenesis of transfusion-related acute lung injury

Answer 28

Donor plasma contains antibodies against host WBCs

Results in antibody-activated neutrophils that damage pulmonary capillaries

Tx = respiratory support

Question 29

A 67-yr-old man is receiving his initial therapy for chronic myelogenous leukemia. His Hgb is 6.3 gm/dL. He complains of chest pain and has ST segment elevation on his ECG. You consider whether to transfuse RBCs. Which option do you elect?

1. No transfusion is needed.
2. Give 1 unit to reach Hgb >7 gm/dL and recheck patient
3. Give 1 unit to reach Hgb >8 gm/dL and recheck patient
4. Give 2 units to reach Hgb >8 gm/dL and recheck patient

Answer 29

b. Give 1 unit to reach Hgb >7 gm/dL and recheck patient

Note: I thought it was d. Give 2 units to reach Hgb >8 gm/dL and recheck patient, but according to piazza the answer is b? Maybe because we’re only supposed to give 1 at a time, even if the goal is >8?

• Usually Hbg increases 1 g/dL per unit of RBCs*
• Target is >8 g/dL in acute cardiac disease, >7 g/dL otherwise*

Question 30

What level of blood loss constitutes need for transfusion?

Answer 30

Blood loss >30% of blood volume

“normal” blood volume = 5L of blood (in a 70 kg man)

So loss of 1.5L or more