Blood transfusion Flashcards
What is the probalem with givign RhD+ve blood to an RhD -ve patient?
Sensitisation –> once it is okay, but can cause formation of anti-D
–> problematic in pregnancy or future transfusion
When is an antibody screen in blood groups done?
how and why?
1-3% of people have additional antibodies (outside RBO) (risk factor: several previouy transfusion )
Therefore:
IAT: INDIRECT ANTIGLOBULIN TECHNIQUE
Done before every transfusion –> (Screen: S of G&S)
IAT: bridges red cells coated by IgG, which can’t themselves bridge 2 red cells – to form a visible clump. Takes 30 mins’ incubation at 37°C
What is an electronical crossmatch?
When can that be done?
Based on data on blood products and antibody testing, plasma are never physically cross -matched
Can be done with recipient who do not have any antbodies on antibody screen
–> once positive: serological crossmatch needs to be done
How and when are serological crossmatches done?
Usually done if any antibodies positive – >
incubation of donor + recipeint blood for 30-40 minutes
What are the main pillars of Patient Blood Management?
Generally used to optimise blood and how it can be managed
What are the indications for transfusion or RBC?
How is it usually transfused (time and dose)
Before: Treat Iron/Folate/B12 deficiency first unless active bleeding
Thresholds
- Most guidelines suggest a threshold of 70g/l if asymptomatic; 80g/l if symptomatic (post-chemo: >80)
- Higher threshold of up to 90-100g/l for patients with coronary heart disease
Others
- Blood Loss: >30% of total blood
How
- Only transfuse one unit at a time unless active bleeding
- Can be transfused “stat” but routinely would be 2-3 hours
What Red cells can be given to what blood groups ?
How are they stored and how should they be given?
Give ABO/D compatible
Group O (negative) in emergency
Stored at 4°C for 35 days
Must be transfused within 4 hours of leaving fridge
Transfuse 1 unit RBC over 2-3 hours
Does ABO and D compatability need to be considered with platelet transfusion?
How are platelet transfusion stored and given?
ABO/D antigens weakly expressed –> **must be ABO matched **
Should be Rhesus D compatible
**Stored at 20°C for 7 days (higher risk of infection) **
Transfuse 1 unit of platelets over 20-30 minutes
What are the indications for Platelet transfusions?
- Any active bleeding / consumption (TTP, DIC, HIT)
- Consumptive disorders e.g. TTP, DIC, HIT
* Do not transfuse unless actively bleeding (plts will be destroyed and transfusion is ineffective) - If massive RBC transfusion (>75 consider transfusion to balance platelets))
- Reduced production e.g. leukaemias
* Transfuse when under 10bn/litre
Higher threshold of 20 in sepsis
* Pre-procedure: Various thresholds depending on procedure
- Prevent Bleeding in surgery
* under 50 (can be higher on vary on site (highest thresholds for eye / brain)
What are the components of FFP?
Plasma, including** all coagulation factors** and plasma proteins
All cellular components are removed from the transfusion product
Unit volume: ∼200–300 mL
What ABO / D compatibiltiy must be considered when giving Cryoprecipitate or FFP?
Why?
RBO must be matched (plasma will/ might still contain antibodies)
D is not important –> does not contain Red cells, therefore sensitisation is extremely rare
What are the indications of giving FFP?
How is it stored and how is it given?
Coinsider using Vitamin K first if appropriate
–> Given for clotting (Pt and APTT abnormalities)
- Do not use unless patient is bleeding or undergoing a procedure e.g. surgery
- Dose depends on patient weight, INR and target INR
- Needs 30 minutes to thaw out first (stored at -24-35 °C for 24-36 months
What are the components of Cryoprecipitate
Has higher Fibrinogen than FFP –>
Clotting factors (fibrinogen, factor VIII, factor XIII), vWF, and fibronectin
What are the indications for giving cryoprecipitate?
- Bleeding associated with fibrinogen deficiency (e.g., due to DIC, liver disease): typically performed if serum fibrinogen is < 100–150 mg/dL
- Alternative therapy for deficiencies in clotting factors, including vWF, factor VIII, and factor XIII
What are the indications for administration of CMV negative blood?
Why?
only required for intra-uterine /neonatal transfusions and
–> for elective transfusion in pregnant women (baby in-utero is exposed to maternal transfusion)
What are the two respiratory acute adverse reactions to blood products?
Which one is the most common and what are the signs + symptoms?
TACO more common - transfusion associated circulatory overoad –> essentially presents as fluid overload and pulmonary oedema
- wihtin 6 hours of infusion
- Resp disress
- Differentiating feautre: TACO presents in patients with pre-existing heart failure /oedema (and symptoms: e.g. increased JVP)
(if at high risk –> think about diuretic administration pre-transfusion)
The other is TRALI- Transfusion-related acute lung injury
- Similar symptoms to TACO
- Abscence of heart failure –> non-cardiogenic pulmonary oedema (immune-mediated)
What is TRALI?
Transfusion-related acute lung injury
Symptoms similar to TACO
- Caused by interaction with anti-HLA antibodies in donor blood with recipient
- Transfusion-related acute lung injury
- Abscence of heart failure –> non-cardiogenic pulmonary oedema (immune-mediated)
What is Transfusion Associated Graft versos host disease?
What is the pathophysiology?
How do you prevent it?
Rare reaction to blood transfusion
Normally: donors blood lymphocytes are destroyed, but in very immunosuppressed patients: donor lymphocytes are not destroyed
–> Lymphocyte-mediated graft vs. host disease
Prevention: use irradiated blood products in very immunosuppressed patients (depleted
lymphocytes)
Presentation: Symptoms include diarrhoea, liver failure, skin desquamation and bone marrow failure
But: always fatal
What tis post-transfusion purpura?
How common is it, how is it treated?
- Relatively rare transfusion reaction
- Due to previous sensitisation to platelt antigens –> mainly in women with multiple pregnancies or multiple blood transfusions
–> Antibody formation against donor platelets (+ destructions of own platelts, unknown why)
Appears 7-10 days post transfusion
* usually resolves in 1-4 weeks, but can cause significant bleeding
Management
* IvIG
*
What is Haemolytic disease of the Newborn?
IgG antibodies against Rhesus factor (from a rh- mother sensitised to D carrying a Rh+ve baby)
–> crossing of IgG antibdoies over placenta
–> destruction of fetal blood
–> presents as
* foetal anaemia
* Haemolytic disease of newborn (anaemia plus high bilirubin - which builds up after birth as no longer removed by placenta)
