255/256 - Blood Transfusions Flashcards
If a patient is acutely bleeding, what is “priority #1” to replace?
IV blood volume; use fluids
Goal is to avoid hypovolemia, hypoperfusion
Which of these infections is most frequently transmitted by blood transfusions?
- HCV
- HBV
- HIV
- Bacterial sepsis (platelets)
- West Nile virus
d. Bacterial sepsis (platelets)
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?
- None needed
- RBCs
- Platelets
- Plasma
- Cryoprecipitate
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)*
What is the highset infectious-disease risk from transfusions?
(Result and type of transfusion)
Bacterial sepsis from platelets
What is the normal immediate response to platelet transfusion?
What constitutes a refractory response?
Normal = platelets rise by 25-30k
Refractory = platelets rise by <10k
1 dose of cryoprecipitate increases a patient’s fibrinogen level by how much…
on average?
Ideally?
Average: 40 mg/dL increase in fibrinogen
(if not consumed)
Ideally: 65 mg/dL
For which blood products (2) do we have pathogen inactivation methods?
Plasma
Platelets
Still in development for RBCs
What is the goal of giving cryoprecipitate to a patient?
Increase fibrinogen levels
List 4 key initial manifestations of transfusion reaction
Fever
Rash
Hypotension
Respiratory problems
What is the goal fibrinogen when you are giving cryoprecipitate?
(How do you know when you’re done?)
>100 mg/dL in pts with bleeding or surgery
>200 mg/dL in obstetric pts
Which element of RBC compatibility testing is most critical?
ABO
What causes graft vs. host disease?
What is the treatment?
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
1 unit of RBCs will increase a patient’s hemoglobin by how much?
1 g/dL
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?
- None—no cryo needed
- One
- Two
- Five
b. One
* Ideal response = 40 mg/dL increase, target is >100 mg/dL*
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?
- Check the transfusion tag patient ID with the patient wristband ID
- Verify the transfusion tag unit # with the blood bag unit #.
- Compare the transfusion tag patient ID and unit # with the blood unit # and the patient wristband ID.
- Read the patient her name from the transfusion tag and her wristband
c. Compare the transfusion tag patient ID and unit # with the blood unit # and the patient wristband ID
What is the effect of plasma transfusion on INR?
Will normalize INR a bit if its really high
If INR is only moderately elevated, INR won’t do much
Which patients are at highest risk of an anaphylactic transfusion reaction?
Patients with selective IgA deficiency
Describe the pathogenesis of acute hemolytic transfusion reaction
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
1 unit of plasma increased a patient’s plasma clotting factor levels by…
<6 percentage points
Describe the pathogenesis of anaphylactic transfusion reaction
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
Which preventive or therapeutic measure is incorrect for the adverse event shown?
- Acetaminophen for febrile reaction
- Leukoreduction for graft-vs-host disease
- Male plasma for transfusion-related acute lung injury
- Blood bank records for delayed hemolytic reaction
c. Male plasma for transfusion-related acute lung injury
* Give respiratory support; there is no TRALI-specific therapy*
What is the hemoglobin threshold for transfusion?
7 g/dL
(8 g/dL in acute carediac disease or thrombocytpenia pts)
What is the treatment for transfusion-related lung injury?
Respiratory support
- There is no specific treatment*
- Caused by antibodies in donor plasma that attack host WBCs*
Which patients are at highest risk of having RBC antibodies?
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
What is the treatment for acute hemolytic transfusion reaction? (4)
Diuresis
Plasma, platelets as needed for bleeding
Blood pressure support
Compatible RBCs if necessary
Caused by host antibodies to donor RBCs
What are the thresholds for giving plasma in a patient who is bleeding or about to undergo a procedure?
- PT:
- PTT:
- PT: INR > 1.7
- PTT: >1.5x normal PTT
What is the universal plasma group?
AB
- Does not have anti-A or anti-B antibodies
- Opposite of universal RBC group*
Describe the pathogenesis of transfusion-related acute lung injury
Donor plasma contains antibodies against host WBCs
Results in antibody-activated neutrophils that damage pulmonary capillaries
Tx = respiratory support
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?
- No transfusion is needed.
- Give 1 unit to reach Hgb >7 gm/dL and recheck patient
- Give 1 unit to reach Hgb >8 gm/dL and recheck patient
- Give 2 units to reach Hgb >8 gm/dL and recheck patient
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*
What level of blood loss constitutes need for transfusion?
Blood loss >30% of blood volume
“normal” blood volume = 5L of blood (in a 70 kg man)
So loss of 1.5L or more
