Blood transfusion Flashcards
When do you use blood tranfusions?
If there is no other possbility
mainly in emergency situations
- trauma + massive bleedings
- very severe anaemia
- clotting disorders etc.
What does the A gene in blood groups code for?
It codes for an enzyme adding galactosamine to fructose stem on cells
–> forms the A antigen
Which antigens and antibodies does a person with blood group A have?
A= A antigens and
Anti-B- antibodies –> can’t get blood that has B antigens (i.e. B+AB)
Which Antigens and Antibodies does someone with Blood group B has?
B
- B-Antigen
- Anti-A-antibody
- –> can’t get blood with A antigen (i.e. A+AB)
Which Antigens and Antibodies does someone with blood group AB have?
AB
- AB antigens
- no anti-antibodies
- –> can recieve any blood donation
Which antigens and antibodies does someone with blood group 0 have?
They have
- no antigens
- Anti -A- and Anti B antigens
- –> can give blood to anyone
Why don’t the Anti- A and Anti-B antibodies in the plasma not affect the blood donation (0) given to patients with groups A or B?
Normally no full blood transfustion
- only packed red cells and no plasma
What happens if you would give a blood transfusion of group B to someone with group A?
IgM anti-B antibodies would bind to blood cells by group B and set of a cytokine strom–>
- lysis of erythrocytes
- aggulation seen (IgM mediated)
Explain the process of blood group testing and matching blood
You need
- patients sample
- test with known anti-A/anti-B antibodies
–> Combine and look for reaction (if aggulation reaction –> not suitable for donation)
If necessary:
- X match with donor blood + recipient
Explain the possible genotype for a RhD + and -ve person
+ ve: Dd or DD
-ve dd
–> recessive gene
Explain the possible genotype of someone having blood group A+B
- A= AA or AO
- B= BB or BO
What happens to RhD -ve people who are exposed to the RhD antigen?
They don’t have the RhD antibody from birth but can develop them furter in life–> can lead to problems in
- another blood transfusion that is +ve (where you would react then)
- in pregnancy with a -ve mother and a +ve foetus –> antigens would destroy the foetus blood cells
What happens when you transfuse a RhD -ve person who has developed Anti-D antigens a RhD +ve transfusion?
otherwise his anti-D would react with RhD posblood - causes delayed haemolytic transfusion reaction - anaemia; high bilirubin; jaundice etc
Reaction within 5-10 days
What is the significance of other antigens present on red blood cells other than A, B and RhD?
Only 8% of people develop antibodies against antigens they don’t have –> normally not matched for
If once antibodies have developed: must use corresponding antigen negative blood otherwise:
risk of delayed haemolytic reaction (can be severe)
Which tests are required to do before a transfusion?
ABO and RhD group, must do an ‘antibody screen’ of their plasma
–> for all the other possible antigens in blood/ on blood cells
In which 3 components is a standart blood sample normally devided?
Normally in
- Red cell component
- Platelets
- Plasma
When do you give red cells in a blood transfusion?
e..g in patients with trauma, hugh blood loss to restore oxygen carring capacity
What does a FFP contain?
Who would recieve it?
FFP= Fresh Frozen plasma (frozen and thawed before use)
- contains coagulation factors
Given to people with reduced blood coagulation (slowed PT+ APTH test)
reversal of warfarin for urgent surgery
Same blood group needed but no x-maching necessary
What is cryoprecipitate?
Who needs it?
Part of plasma high in Fibrinogen and Facotr VIII
Given to patients with
- massive bleeding and fibrinogen very low
- Rarely hypofibrinogenaemia
What are the characteristics of a platelet donation?
Who recieves it?
Shelf life of only 5 days with agitation
- no x match required but choose same blood group (as otherwise lifespan of platelets shortened)
- RhD sensitisation possible (because of contamination with red cells)
Given to patients with
- thrombocytopaenia
- Mainly in cancer/bone marrow failure
- also in massive bleeding of DIC
- reversing effects of anti-platelet drugs
Which blood transfusion products are usually obtained via fractionated prodcuts?
- Single clotting factors
- VIII, IX in haemophilia
- Factor VIII in VWD (because is VWB factor is low, VIII is also low (VWB stabelises factor VIII)
- lImmunoglobulins
- Albumin
Explain the transfusion of Immunoglobulins
Used for:
- IM: Specific - tetanus; anti-D; rabies
- IM: Normal globulin - broad mix in population (eg: HAV)
- IVIg – pre-op in patients with ITP or AIHA
How are blood donors tested?
What are the criteria?
Blood donors within high risk groups/risk behaviours are excluded
Blood is tested for infections (no 100% certainty):
- Hepatitis B - HBsAg, PCR
- Hepatitis C - anti-HCV, PCR
- HIV - anti-HIV, PCR
- HTLV - anti HTLV
- Syphilis - TPHA (spirochete)
- Hepatitis E - PCR
- Some also tested for CMV (virus)
Questionnaire: e.g. malaria (exclude when recent travelling etc.)
vCreutzfeldt-Jacob disease also can be transmitted but very very rare
How are platelet donations stored and what is their shelf life?
Stored at 22° (Room temperature and constantly agitated)
Shelf life: 5 days
(increased risk of infection due to warm storing temp)
What is the storage and shelf life of FFP?
Fresh Frozen Plasma
(Same storage for Cryorecipitate)
- collected (300ml) and frozen within 6h
- Stored at -30°
- Shelf Life: 2 years
