Blood Transfusions

Question 1

What is our only source for blood and what is important about it?

Answer 1

Humans!

NO synthetic source yet that is risk-free

It is a SCARCE resource so needs to be used carefully

Question 2

When is blood transfusion normally used?

Answer 2

Only use when NO other safer alternative is available
e.g. massive bleeding - ‘plain fluids’ not enough
anaemia - iron/B12/folate not appropriate

Question 3

What is the most important of all blood groups?

Answer 3

ABO blood groups

Question 4

Describe the ABO blood groups

Answer 4

1. Groups A & B have an EXTRA SUGAR RESIDUE attached (to the common glycoprotein & fructose stem)

o ‘A’ gene codes for N-acetyl galactosamine
o ‘B’ gene codes for galactose

2. Group O has NO EXTRA SUGAR

o just the fructose stem

Question 5

What is unique about the ‘A’ , ‘B’ and O genes?

Answer 5

‘A’ & ‘B’ genes are CO-DOMINANT

O gene is RECESSIVE

i.e. Blood group A - genes could be AA or OA

Question 6

Which blood group is the universal DONOR?

Answer 6

OO-

Question 7

Which blood group is the universal RECIEVER?

Answer 7

AB+

Question 8

Why are ABO Group antigens and Abs so important?

Answer 8

Person has Abs AGAINST any antigen NOT present on own RBC

i.e. patient w. Group A will have Abs AGAINST Group B blood

Question 9

Which Ab reacts against mis-matched blood?

Answer 9

IgM

A 'complete' Ab so if activated:
 o causes a COMPLETE complement cascade
 o haemolysis of RBCs
 o Agglutination of RBCs
 o FATAL!

Question 10

Antigens and Abs for Blood Group A?

Answer 10

Blood Group - A

Antigens of RBCs - A

Abs in plasma - Anti-B

Question 11

Antigens and Abs for Blood Group B?

Answer 11

Blood group - B

Antigens of RBCs - B

Abs in plasma - Anti-A

Question 12

Antigens and Abs for Blood Group O?

Answer 12

Blood group - O

Antigens of RBCs - N/A (so can be donor!)

Abs in plasma - Anti-A & anti-B

Question 13

Antigens and Abs for Blood Group AB?

Answer 13

Blood group - AB

Antigens of RBCs - A & B

Abs in plasma - N/A (so can receive any!)

Question 14

How are blood groups tested for matching?

Answer 14

Patient’s blood tested by reacting it with known anti-A & anti-B reagents

A donor is then selected
The blood is cross-matched to be sure (x-match) - check for agglutination

Question 15

RH blood groups?

Answer 15

RhD is the most important!

RhD+ = have D-antigen (on RBC)
RhD- = NO D-antigen (on RBC)

Question 16

Genetic profile of RhD gene?

Answer 16

Co-dominant!

e.g. dd = NO D-antigen
Dd/DD = D-antigen present

Question 17

% of people in each blood group?

Answer 17

A - 42%
B - 8%
O - 47%
AB - 47%

85% are RhD+
15% are RhD-

Question 18

How are blood grouped named?

Answer 18

Usually shortened

i. e. ABO (ABO blood group) +/- (RhD status)
e. g. AB+ (AB blood group) (RhD+)

Question 19

What can happen to RhD- people however?

Answer 19

Can make D-Abs AFTER exposure to RhD antigen!

i.e. by transfusion of RhD+ blood OR in women if pregnant with RhD+ child

Question 20

What is different about anti-D Abs in comparison to the ABO Abs?

Answer 20

It is IgG Abs!

SO not as bad as IgM

Question 21

Antigens and Abs for RhD+?

Answer 21

Antigen = D +

Abs = N/A

Question 22

Antigens and Abs for RhD-?

Answer 22

Antigen = N/A

Abs = CAN make anti-D if sensitised

Question 23

What are the implications for RH blood groups due to the possibility of anti-B sensitisation?

Answer 23

1. Future transfusions

After receiving a RhD+ transfusion (if patient is RhD-):
o patient MUST have RhD- blood
OTHERWISE
the anti-D Abs they had made from the first transfusion would react!

Would cause DELAYED HAEMOLYTIC TRANSFUSION REACTION causing anaemia, high bilirubin, jaundice etc.

2. HDN - haemolytic disease of the newborn

RhD- mother had anti-D Abs made post-transfusion
o then if in her NEXT pregnancy has a child that is RhD+, the mothers IgG Abs will cross the placenta and attack the child’s RBCs

Question 24

What is important about RhD Group in terms of anti-D Abs?

Answer 24

AVOID RhD- patients making anti-D Abs

Question 25

How can you avoid the issue w. RhD group and anti-D Abs?

Answer 25

1. Transfuse blood of the same RhD Group as the patient o Remember - can give RhD- to ANY patient as no antigens! 2. O- blood is used in an emergency o as it CANNOT react with any combination in the patient (no antigens!)

Question 26

What are the other blood groups?

Answer 26

Other antigens on RBCs that we DO NOT routinely match e.g. RhC, c, E, e and others e.g. Kell, Duffy, Kidd

Question 27

What is a risk regarding the other blood groups?

Answer 27

About 8% of patients transfused form Abs to the other blood group antigens! So once the patient has formed these Ab, must use corresponding antigen -ve blood OR risk of delayed haemolytic reaction

Question 28

How do we know if a patient will need antigen -ve blood?

Answer 28

BEFORE each transfusion, test the patient's blood sample for RBC Abs Therefore, as well as testing their ABO and RhD groups, must also do an: ANTIBODY SCREEN of their plasma

Question 29

A woman is O positive; her partner is AB positive. Which of these cannot be a child of theirs?

Answer 29

AB+ & O+

Question 30

A patient is B positive. Which of the following blood could kill them? A positive O positive B negative

Answer 30

A+

Question 31

How is blood given to a patient and why?

Answer 31

Give patients what they need of the component of blood - this is to: o stop waste o certain components degenerate quickly is stored as whole blood o NOT fluid overload patients SO centrifuge the blood to form: o TOP = plasma o MIDDLE = platelets o BOTTOM = RBCs

Question 32

Characteristics of RBCs?

Answer 32

1 unit/donor o stores for 5 weeks at 4oC o given via blood giving set - has filter to remove clumps/debris o NOT normally given frozen (only for rare groups) - as poor recovery upon thawing

Question 33

FFP?

Answer 33

Fresh frozen plasma

Question 34

Characteristics of FFP?

Answer 34

1 unit/donor (dose is 3 units) o store for 2years at -30oC - thaw 20-30mins before use (give ASAP or coag factors degenerate at room temp) - NO x-matching needed BUT need blood group (as contains ABO Abs so could cause haemolysis)

Question 35

What are some indications when FFP needs to be used?

Answer 35

Need to use: 1. If BLEEDING & abnormal coag test results (PT, APTT) o monitor response clinically & w. coag tests 2. Reverse effect of Warfarin (anticoagulant) o e.g. for urgent surgery (if PCC not available - prothrombin complex concentrates)

Question 36

Cyroprecipitate?

Answer 36

Formed from FFP thaw residue! (1 dose from 10 donors) Stored at -30oc for 2 years ``` Contains o Fibrinogen o F8 SO given for massive bleeding & very low fibrinogen (rarely for hypofibrinogenaemia) ```

Question 37

How is platelets given as blood donation?

Answer 37

1 pool from 4 donors OR 1 donor by apheresis (cell separator machine) Stored at 22oC (but constantly agitated) for 5 days only as risk of bacterial infection! Need to be given in plasma suspension as if not, platelets would agglutinate

Question 38

What do you need to know before giving platelets?

Answer 38

Blood-group BUT x-match NOT necessary Platelets have LOW LEVELS of ABO antigens SO wrong platelet group would be destroyed quickly Can cause RhD sensitisation however as some RBC contamination

Question 39

What are some indications when platelets needs to be used?

Answer 39

o Bone marrow failure o massive bleeding (or DIC) o surgery (patient has LOW platelet levels) o Cardiac bypass (patient on anti-platelet drugs)

Question 40

If a patient is bleeding post surgery, what components does he need if: a) His platelet count is normal and his coagulation test (PT and APTT) are prolonged? b) His PT and APTT are long and his fibrinogen is low?

Answer 40

A - needs FFP Because his PT and APTT are both prolonged suggesting that there are problems in the EXTRINSIC & INTRINSIC pathways SO MORE THAN ONE factor is missing B - need FFP & Cryoprecipitate Cryoprecipitate only has fibrinogen & F8 and so will solve the low fibrinogen problem BUT the FFP will supplement the other coagulation factors

Question 41

What are fractioned products?

Answer 41

Taken from a large pool (1000s) of donors, mixed and fractioned off (like oil)

Question 42

What are potential products from Fractioned products?

Answer 42

1. F8 and F9 o for haemophilia A & B AND o F8 for vWD - It is heat treated to inactivate viruses - Recombinant F8 and F9 alternatives increasingly used but £££ 2. Igs (to treat specific illnesses) o IM-Ig - specific e.g. tetanus, anti-D, rabies o IM-Ig - normal globulin (broad mix in population e.g. HAV) o IV-Ig - Pre-op patients with ITP or AIHA (autoimmune haemolytic anaemia) 3. Albumin o 4.5% - for burns, plasma exchange etc. o 20% - severe liver & kidney conditions

Question 43

Protocol in place for donors?

Answer 43

1. Blood kept safe for patient by o testing for infections o exclusion of donots by a questionnaire 2. Donors also kept safe by o exclusion of risky donors e.g. if have heart problems

Question 44

Infection that all blood bust be tested for?

Answer 44

Includes: ``` o Hep B and C o HIV o HLTV (Human T-lymphocyte Virus) o Suphilis o CMV or HEV ```

Question 45

Impact of 'window period' and donors?

Answer 45

'Window period' of infections! When levels are TOO LOW to detect in system so will go by undetected SO cannot only rely on testing

Question 46

Some infections could also be transmitted via. blood transfusion - include?

Answer 46

Prion disease - VCJD As a precaution, all plasma pooled to make fractioned products is obtained from USA (UK plasma used for FFP, rest thrown away) AND all blood components have WBCs filtered out (WBC essential for uptake of vCJD prion into brain)