blood transfusions

Question 1

what are the steps in getting the blood

Answer 1

Question 2

what are ABO groups determined by

Answer 2

1. antigens (sugars) on the red cell membrane.
2. naturally-occurring antibodies (IgM) in the plasma.

Question 3

consequence of ABO incompatible blood test

Answer 3

massive INTRAVASCULR
haemolysis

potentially fatal

Question 4

proportion of RhD +ve patients

Answer 4

85%

Question 5

what can different rhesus statuses recieve

Answer 5

+ve :
* RhD -ve red cells
* RhD +ve red cells

-ve :
* RhD -ve
* because make immune anti-D if exposed to +ve red cells - this is very immunogenic -> more likely to make other Ab

Question 6

summarise immune anti-D Ab

Answer 6

Are IgG (so cross the placenta)

Do not cause direct agglutination of RBCs

Cause delayed haemolytic transfusion reaction

There are some other Rh antigens e.g., C, c, E and e

Question 7

what are the other Ag and are they tested for

Answer 7

Kell (K), M, N, S, Duffy (Fy), Kidd (Jk),

only match for these if patient has corresponding antibody (or occasionally in certain other situations)

Kell – important in maternity

Duffy and Kidd – delayed haemolytic reaction – important if chronically dependent on transfusion

Question 8

who can get Rh -ve blood

Answer 8

anyone

short supply

Question 9

what happens if Rh-ve get +ve blood

Answer 9

happens in emergency/shortage

no acute problem

induce anti-D formation - picked up in lab next time
-> get RHd -ve blood

save Rhd -ve blood for people of childbearing potential because can cause:
* haemolytic disease of newborn
* severe fetal anaemia
* hydrops fetalis (heart failure)

Question 10

when do you test blood group

Answer 10

before every transfusion, even if it has been done many times before

Question 11

how is blood group tested

Answer 11

Use known anti-A and anti-B and anti-D reagents against patient’s RBCs ** “forward group**”
reagents are monoclonal Ab and are saline reacting at room temp

And “reverse group”: known A and B group RBCs against patient’s plasma (IgM antibodies)
this is internal control
newborns have weak reverse gp because Abs not formed yet

if been transfused with blood that is not the same group as own (group O blood to a group A patient for example) will have a dual population of red cells (A and O) and the reverse group will only have anti-A

Question 12

what is Ab screen for

Answer 12

because cant test all RBC Ag

pts have Ab from exposure to other cells eg in pregnancy and transfusion

see what Ab the patient has and transfuse RBC w/o that ag

to prevent delayed haemolytic transfusion reaction (>24hr post) - extravascular haemolysis in the spleen

Question 13

summarise automated blood grouping and Ab screening

Answer 13

Bar coded samples (id correct throughout – no mix up)

Computer interfaces – reduces transcription errors

Robotic sample and reagent handling

Liquid level sensors (? failed to add reagent)

Reading of results by image analysis

Interpretation of results from digital photographic image

Download to patient record

Question 14

how do you do an Ab screen

Answer 14

2 or 3 reagent red cells containing all the important red cell antigens

incubate the patient’s plasma and screening cells using indirect antiglobulin technique

Immune antibodies are of variable strength and need help to bind to the antibody screening cells.

Low ionic strength saline brings the cells closer together and the mixture is incubated at 37C
An antiglobulin reagent (anti-human IgG) is added to show if there is an antigen-antibody interaction
If there is an immune antibody the red cells will clump – POSITIVE SCREEN
If there is no antibody the red cells stay in suspension – NEGATIVE SCREEN

Question 15

what is electronic issue

Answer 15

selection and issue of red cell units

where compatibility is determined by IT system,

without physical testing of donor cells against patient plasma

Question 16

why do electronic cross match

Answer 16

Quicker
Fewer staff
No blood on stand by
Issue blood remotely
Better stock mx
can even release blood from a fridge on another site – this is called remote issue.

Question 17

who is not suitable for electronic cross match

Answer 17

anomalous blood groups,

those with red cell antibodies

those who have only had a blood group tested once.

Question 18

what is serological cross match

Answer 18

1. FULL CROSSMATCH
   INDIRECT ANTIGLOBULIN TECHNIQUE
   takes at least 40 min - not suitable for emergency
2. IMMEDIATE SPIN (SALINE, ROOM TEMPERATURE)
   Incubate patient plasma and donor red cells for 5 minutes only
   and spin, will detect ABO incompatibility only
   used for emergency - prevent immediate but not delayed haemolytic reaction

Question 19

what happens if +ve Ab screen

Answer 19

lab have to detect what the Ab is
uses panels of RBC with known phenotype
do Indirect antiglobin technique

Enzyme treating the reagent cells can enhance the antigen : antibody interaction for some antigens (e.g. Rh antigens)

Question 20

what is on the label for donor blood

Answer 20

ABO and D
Kell
other Rh ag

all have traceability tag - legal requirement

Question 21

what is on the label for donor blood

Answer 21

ABO and D
Kell
other Rh ag

all have traceability tag - legal requirement

Question 22

when do you give kell negative blood

Answer 22

women of childbearing potential

because anti-K can cause HDFN.

85-90% of the population is K-negative.

Question 23

what are the 3 pillars of patient blood management

Answer 23

1. optimise haemopoiesis - identify pre-op anaemia and treat
2. min blood loss and bleeding
3. harness and optimise physioological tolerance of anaemia

Question 24

features of 2nd pillar of patinet blood mx (min blood loss and bleeding)

Answer 24

Know if on anticoag/plt –stop
TXA
Blood sparing techniques
Cell salvage – if clean blood – not bowel/cancer

Question 25

features of the 3rd pillar of patient blood mx (harness and optimise physioological tolerance of anaemia)

Answer 25

**optimise cardiac output** **Restrictive transfusion threshold** – reduce threshold down to 70 if no cardiac impairment and not haematologically unstable

Question 26

things to consider when considering a transfusion

Answer 26

Is the patient bleeding? What are the blood results? * is it just anaemia, can it be treated differently * have haemotynics been done Is the patient symptomatic? Will a transfusion solve the problem? What are the risks of transfusion? * hep B C HIV Are there alternative treatments?

Question 27

patient consent for blood transfusions

Answer 27

verbal and written (SaBTO - Safety of Blood Tissues and Organs) informed afterwards if in emergency why alternatives not appropriate (iron/B12/EPO/folate/cell salvage) need to involve pts so that they get special requirements

Question 28

when do you stop clopidogrel

Answer 28

5-7 days before surgery

Question 29

when do you stop warfarin

Answer 29

5 days before surgery

Question 30

things to consider in pre-assessment clinic

Answer 30

anaemia thrombocytopenia bleeding disorder connective tissue disorder thrombophilia Jehovah's witness *If likely to bleed a lot eg connective tussye disorder – make sure have appropriate blood and clotting factors – they normally keep as little on site as possible – but if give warning then can make sure have right stock*

Question 31

summarise red cell product

Answer 31

Give **ABO/D compatible** Group O (negative) in emergency Consider special requirements Stored at **40 C for 35 days.** Must be **transfused within 4 hours** of leaving fridge Transfuse **1 unit RBC over 2-3 hours** In life threatening might give quickly

Question 32

summarise plt product

Answer 32

ABO/D antigens weakly expressed Should be **D compatible** Consider special requirements **If group O given to A, B or AB patients select ‘high-titre’ negative (anti-A/B antibodies)** Stored at **20 C (room temp) for 7days** = more concern for **infection** * If plts and then get fever – broad spectrum Abx and let lab know – will culture the blood * test blood that will be used for plts – for infection. Transfuse **1 unit over 20-30 minutes**

Question 33

summarise FFP blood product

Answer 33

Give **ABO compatible** (D group does not matter) **AB plasma is universial donor** as it has no anti-A/B antibodies but it is in short supply So **give A high titre -ve** No need to cross match but does take **30-40 minutes to thaw** Once thawed can be kept at **4 C for 24 hours** Transfuse **1 unit over 20-30 minutes**

Question 34

summarise cryoppte product

Answer 34

Give **ABO compatible** (D group does not matter) **AB plasma is universial donor** as it has no anti-A/B antibodies but it is in short supply So **give A high titre -ve** No need to cross match but does take **30-40 minutes to thaw** Once thawed has to kept at room temperature and **use within 4 hours** Transfuse **1 unit over 20-30 minutes**

Question 35

what is MSBOS

Answer 35

maximal surgical blood ordering schedule agreement about predictable loss some operations rarely/always need a lot of blood Blood allocated to a patient, if not used are taken back into stock... repeatedly. – as long as back within 30 mins can reissue up to 3 times

Question 36

when do you transfuse red cells

Answer 36

Check Hb pre transfusion and after every 1-2 units 1 unit RBC gives a Hb increment of 10g/L in a 70-80 kg patient Transfusion to above 100g/L is rarely required, unless symptomatic or severe cardiac/respiratory disease etc.

Question 37

when do you transfuse platelets

Answer 37

Want to keep plt count above 50 If septic – want above 20 Head, neck, eye surgery – want to keep plt count above 100 Plt dysfunction or immune cause – only give if active bleeding CI in: Haparin induced thrombocytopenia thrombosis And TTP If having interventional procedure – **give plts when do the procedure**, not before because they will have consumed the patients. Give plts **as knife goes to skin** **One unit usually raises platelet count by 30-40 x109/L**

Question 38

FFP indications and dose

Answer 38

Question 39

when do you give cryoprecipitate

Answer 39

More fibrinogen than FFP If low fibrinogen – give CPTT 2 pools is an adult dose Raise fibrinogen by 1g/L

Question 40

can you have autologous blood transfusion

Answer 40

not in UK - futile, no net gain & doesn’t avoid problems of wrong blood or bacterial contamination can have intra-op cell salvage - centrifuge, filter (all coag factors and plts removed), wash & re-infuse it Post-operative cell salvage Collect blood lost post-op into wound drain – filter & re-infuse Mainly orthopaedic (knee surgery)

Question 41

CMV negative blood

Answer 41

only required for: * **intra-uterine /neonatal transfusions** * **elective transfusion in pregnant women** (baby in-utero is exposed to maternal transfusion)

Question 42

irradiated blood

Answer 42

for **highly immunosuppressed** patients, who **cannot destroy incoming donor lymphocytes**: -> (fatal) transfusion associated **graft versus host disease (TA-GvHD)**

Question 43

washed blood

Answer 43

red cells and platelets are only given to patients who have **severe allergic reactions to some donors’ plasma proteins** adds 4-5hrs – so cant get in an emergency

Question 44

taking blood

Answer 44

identify wrist band ask to state DOB and name label sample at bedside

Question 45

what is the most common blood gp

Answer 45

O positive

Question 46

why is O negative use increasing

Answer 46

Not just HEMs Red cell exchanges - Automated red cell exchanged for sickle – often give O negative Inappropriate use Wastage