Transfusion Medicine Flashcards
What is the most common blood product you will need?
• What does it consist of?
• How much is in a unit, and how much does it increase Hgb?
Most Common:
• Packed Red Blood Cells
Consist of:
• Only RBCs that have been spun down to remove plasma and platelets
How Much:
• 250 ml per unit, this increases Hgb by ~1g/dL
How long can you store Packed RBCs?
• why has this time period been chosen?
42 days = storage time
• Only up to 25% of transfused RBCs will lyse within 24 hours of transfusion
T or F: most hospitals outside of military hospitals and the VA use leukoreduced packed RBCs.
True, this is because there is little evidence supporting that it makes any difference
Why is Plasma typically given to patients?
• Unit size?
• Compatibility?
Typically Given to patients with Clotting issues
Unit Size:
• 200-250 ml
Compatibility:
• MUST BE ABO MATCHED (all donor Abs are present)
What is cryoprecipitate?
• Why would you use it instead of plasma?
Cryoprecipitate:
• Proteins that precipitate out of plasma at 4˚
Why use it:
• Improves clotting by providing clotting proteins without the risk of VOLUME overload
What clotting proteins is cyroprecipitate used to replace?
• size of unit
• Compatibility
Proteins: • Fibrinogen • Factor VIII • Factor XIII • vWF
Size of Unit:
• 15 mL (much smaller than 200-250 for plasma)
Does NOT have to be ABO compatible
When are platelets most commonly used?
• How are they prepared?
To stop bleeding in a patient that has a low platelet count (BELOW 50 K/µL)
**Less frequenty use for pts. at risk of spontaneous bleeding (platelets below 10 K/µL)
Preparation:
•Plasmaphoresis or Differential Centrifugation
What is the difference between using plasmaphoresis and differential centrifugation to get platelets?
In differential centrifugation you need donations from 5 to 6 people to equal 1 unit of platelets obtained from plasmaphoresis
**Plasmaphoresis is most commonly used
Suppose you have a patient with a platelet count of 49 K/µL and they are actively bleeding.
• What will you treat them with?
• compatibility?
• What will there count be after administration of 1 apheresis unit?
- Platelets
- Not ABO match necessary but platelets DO express ABO antigens
- 74 K/µL will be the patients count after one 300 ml apheresis unit is administered
**each unit raises the platelet count by ~25 K/µL
How long can platelets be stored?
4-5 days
What is the most common reason to transfuse a patient?
• what will you give them?
Severe Anemia is the most common reason to do a blood transfusion so you’ll most likely give Packed RBCs (whole blood transfusions are rarely done)
What does the O-antigen consist of?
• what is it attached to?
Carbohydrates:
• GlcNac-Gal-GlcNac-Gal-Fructose
Attachment:
• linked to Sphingosine or membrane Protein
What enzyme catalyzes the transformation of the O-antigen into A or B?
• what does the enzyme do in type O people?
• ABO glycosyltransferase attaches a 6th sugar to the O antigen (GlcNac-Gal-GlcNac-Gal-Fructose)
Type A:
• GalNac is added
Type B:
• Gal is added
What is the difference between type A and B blood and type AA and BB blood?
Type A and B:
• these people have one allele for A or B and one allele for O
Type AA and BB:
• People have two A alleles or two B alleles
What type of Abs. exist against A and B antigens?
• Concentration in blood?
IgM antibodies so they can FIX COMPLEMENT
Conc:
• Usually present in HIGH TITER
What are the two most antigenic proteins on red cells?
• Number of antigenic sites on each protein?
RhD (one antigenic site) and it’s homolog RhCE (two antigenic sites)
What mothers are a risk for having antibodies that attack their fetus?
• how do we prevent this?
• Rh(-) mothers that have Rh(+) children may develop Rh specific antibodies during pregnancy or delivery
Prevention:
• anti-Rh-gamma
T or F: in an emergency situation Rh(-) individuals can be transfused with Rh(+) blood.
True, this is not ideal but is sometime necessary
If you infuse an Rh(-) individual with Rh(+) blood, what should you consider?
If its a female of childbearing age (or before) we do NOT want to do this because there’s and 80% chance she’ll develope Rh+ abs.
What immunogenic risks are there for transfusing plasma other than having to match ABO?
• most common case?
- If the recipient is lacking an entire class of plasma proteins then they can make antibodies to those proteins after transfusion
- Most Frequently happens in IgA deficiency (1/300)
What is the lifespan of a platelet?
• is this affected by the ABO match in the case of a transfusion?
• Limitations?
Platelet Lifespan:
• ~10 days
ABO types:
• Platelets express ABO antigens, because they are targeted by the immune system they will be eliminated faster but MISMATCHES ARE STILL EFFECTIVE in ACUTE situations
Limitations:
• after 5-10 transfusions platelets stop going up following the transfusion
What is the major exception to the fact that plasma (if you’re just giving one unit) doesn’t have to be matched?
1 The ABO type of the platelets need to be matched in the case that the plasma is not matched
**If recipient has very low blood volume e.g. NEONATE then you’ll want to avoid the risk by matching blood types
What is the difference between matching plasma and matching RBCs as far as universal donors and acceptors go?
RBCs:
• AB+ is a universal acceptor (O- is universal donor)
Plasma:
• O is universal acceptor (b/c they already have antibodies built up against everything, AB can’t recieve anything but AB+ because any other plasma will attach their antigens)
T or F: anti-D (anti-Rh factor) antibodies are irrelevent in plasma transfusions
True, this is because people who make anti-Rh (anti-D) antibodies are not allowed to donate plasma
When do you have to start worrying about minor (non-ABO or Rh) blood antigens coming into play?
In pts. that receive multiple transfusions
Blood bank has to check EVERY TIME to make sure your serum doesn’t react with these
**note: there are like 350 of these RhCE is one of them
What is the difference between a type and screen and a crossmatch?
Type and Screen:
When - order if transfusion is needed or it may be needed
• Current blood specimen is typed (ABO and Rh) and screened for Abs to minor RBC antigens
Crossmatch:
When - order if transfusion is needed or prior to surgeries where major blood loss is likely
• Mix donor red cells with patient plasma and look for Agglutination (Incompatibility) under microscope
Why is the type and screen usually not proceeded by a crossmatch?
99.9% of the time if the type and screen are negative the crossmatch is too
In what cases is it okay to infuse blood into a patient that hasn’t been typed and screened?
O- blood can be released from the bloodbank in emergency situations
T or F: minor blood group antigens typically become an issue immediately on transfusion.
False, these will only become an issue if you are transfused with blood containing that same minor blood group antigen a second time
ANYTIME YOU SUSPECT YOUR PATIENT MAY UNDERGO SUBSTANTIAL BLOOD LOSS SEND A SAMPLE TO THE BANK
ANYTIME YOU SUSPECT YOUR PATIENT MAY UNDERGO SUBSTANTIAL BLOOD LOSS SEND A SAMPLE TO THE BANK
***What is the ultimate objective of doing a RBC transfusion in the 1st place?
INCREASE THE PATIENTS OXYGEN CARRYING CAPACITY
You have a severely wounded patient that has lost a lot of blood. What type of blood transfusion should you give them?
• how will hct and hgb be affected?
**In people who have lost a large amount of blood volume you need to replace EVERY COMPONENT OF THE BLOOD - Red cells, Platelets, Plasma
**Hct and Hgb won’t be affected
T or F: Hbg below 7 g/dL is an indication for transfusion
False, most of the time lab numbers should NOT be used as an indication for transfusion
What are the 4 REAL indications for a blood transfusion?
Patient is symptomatic
• INC. HR, RR, confusion/weakness/dizziness
Acute Blood Loss and/or Rapid Volume expansion
During or Immediately after acute MI
• Increased Mortality at Hgb less than 10
A clear trendline (of blood loss) that you can’t reverse
Do pts. with renal failure need transfusions for their low RBC counts?
Often no because they are adapted to low Hgb
T or F: otherwise healthy pts. can tolerate HgB less than 7 g/dL
True
RBC transfusion are NOT indicated for: • Old and Frail Pts. following surgery • Asymptomatic Coronary Artery Disease • Expanding Blood volume • Promote wound healing
RBC transfusion are NOT indicated for: • Old and Frail Pts. following surgery • Asymptomatic Coronary Artery Disease • Expanding Blood volume • Promote wound healing
In hypotensive patients how should you increase blood volume?
Isotonic IV fluids, these people don’t need more blood
What are some conditions in which you might use plasma to replace missing plasma protein?
• For which of these is plasma the 1st choice of therapy?
Single Plasma Prot. Def.:
• Hemophilia A or B (Factor VIII or IX)
• Antithrombin III Deficiency
• AdamTS13 (TTP)
Mutliple Plasma Prot. Def.:
• Coumadin Toxicity with bleeding
In TTP (thombotic thrombocytopenia purpura) plasma is the 1st choice of therapy
In what cases are platelet transfusions indicated?
- Treatment of ONGOING HEMORRHAGE in thrombocytopenic pt. (plts. less than 50K/µL)
- Prevent spontaneous hemorrhage in pts. with SEVERE THROMBOCYTOPENIA (plts. less than 10K/µL)
- Treat or Prevent hemorrhage in pts. with DYSFUNCTINOAL PLATELETS
- Prevent Hemorrhage in ps. undergoing INVASIVE PROCEDURES
What is the standard of care for giving platelets to a pts. that are thrombocytopenic and undergoing an active bleed?
• Level of evidence?
• Transfuse the pt. with platelets at counts less than 50 K/µL
Level of Evidence:
• Weak
What is the standard of care for platelet transfusions in severely thrombocytopenic pts?
• Level of evidence?
• Transfuse the pt. with platelets at counts less than 10 K/µL
Level of Evidence:
• Actually is some support that this helps
What kind of pts. often have dysfunctional platelets that need platelet transfusion?
• Level of evidence?
- Recent Cardiopulmonary Bypass
- Treatment with irreversible platelet inhibiting drugs
Level of Evidence:
• Low
What platelet threshold can be used for patients that need to get a central line placed?
20 K/µL and below it is beneficial to transfuse
What are the 4 major categories of bad transfusion outcomes?
- Immune Responses
- Volume Overload
- Transfusion Transmitted Infection
- Graft vs. Host Disease
What types of immune responses are seen in bad transfusions?
• Which is the most important?
- Acute Hemolytic Reaction
- Production of Antibody to Minor Red Cell Antigens
- Urticarial Rxn to Transfused Plasma Proteins
- Febrile Reaction to transfused Leukocytes
What are some symptoms that indicate that an Acute Hemolyic Immune Response is happening post transfusion?
• What makes this type of reaction so deadly?
Symptoms:
• Fever, Chills, Nausea
• Chest pain, Dyspnea, Flushing
• Hemoglobinuria
Why is it deadly:
• Hgb that is free in the plasma will clog up the glomerulus in the kidney leading to renal failure
If a patient comes back a week later and needs a second transfusion what should you do?
Send Blood Specimen to the blood bank to detect antibody that has been formed against MINOR Blood Group antigens
What large group of patients are at an elevated risk of forming antibodies to minor blood group antigens?
• Why?
Pts. with Sickle Cell Anemia at 30% risk, while general population is at 4% risk
Why?
• Sickle Cell Pts. are typically African Americans and most blood donors are white so there is a greater likelihood that minor blood group antigens are different between donor and pt.
What should you do if you need to transfuse a sickle cell patient?
Do an EXTENDED PHENOTYPE or EXTENDED CROSSMATCH
• This means that in addition to doing ABO and Rh matches, you also test for a small group of MINOR blood group antigens
Why would you get a urticarial response after giving someone an RBC transfusion?
Some Plasma Proteins still remain in Packed RBCs and these are very diverse. If your body doesn’t recognize the protein then a you may get an IgE response.
***Can also cause anaphylactic reaction - MOST COMMON IN PPL. WITH IgA deficiency
What two things should be in your DDx of immune response causing fever after Transfusion?
• How you know the difference?
- Acute Hemolytic Reaction
- Febrile Reaction due to transfused Leukocytes (1% of transfused pts)
GO EXAMINE THE PT.
• Look for Shortness of Breath, Acute Abdominal or Chest Pain, Hematuria
What efforts are made to ensure that Febrile Reactions don’t occur due to transfused Leukocytes?
• Treatment if the Rxn does occur
Leukocyte Reduced Packed RBCs can be used
*Treat with Tylenol
***What is the MOST common cause of Adverse Transfusion Reactions?
• Pts. that are particularly Susceptible?
VOLUME OVERLOAD***
Pts. Susceptible:
• CONGESTIVE HEART FAILURE pts. are less likely to handle the increased work load
How much is blood volume increased with 2 units of packed RBCs?
• What adverse effects does this have in pts. with congestive heart failure?
• What do you do if you are afraid a pt. is suffering from volume overload?
10%
Adverse Effects in CHF:
• Failure to handle extra cardiac workload lead to edema and fluid accumulation in organs INCLUDING the LUNGS
Treatment of Vol. Overload:
• Diuretics are used to reduce the blood volume
What is the current risk for transmitting HIV, HCV, HBV or other viruses to people via a blood transfusion?
• How do we prevent this?
1 in 100,000
Prevention:
• Screen Donors
• Use PCR based tests to screen serum
What cause GVHD in transfused pts.?
• What pts. are at the greatest risk?
• How do we reduce risk?
GVHD
• Mediated by Leukocytes against host tissues (G.I. Epithelial Sloughing)
Who:
• Occurs most commonly in Immunocompromised Recipients
Risk Reduction:
• Leukocyte Reduced RBCs
• Irradiation of Blood Kills Leukocytes (0% risk of GVHD)
