Haem 7 + 8 - Blood transfusion Flashcards
what kind of antibodies are
anti-B, anti-A ab
Anti-D ab
anti-B, anti-A ab - IgM
Anti-D ab - IgG
What kind of reaction do anti-D antibodies produce when they cross the placenta?
Delayed haemolytic transfusion reaction
Group and screen vs full Xmatch
Group and screen – check ABO group and plasma antibodies in patient
Full crossmatch – checks patient’s blood against donor blood specifically
o If no antibodies present in the patient’s blood, a crossmatch is not needed
o if antibodies are present, always crossmatch
How is the grouping of the RBC done?
both of the below are done and included in a “Group and Screen”:
o (1) Forward group – Use known anti-A, anti-B and anti-D reagents against the patient’s RBCs
o (2) Reverse group – known A and B groups red blood cells are mixed with the patient’s plasma (IgM antibodies)
This group acts as an internal control – if it does not match, this is an anomalous result
New-borns often have a weak reverse group as their antibodies have not developed fully yet
o Column agglutination technology
o Positive result = agglutination at the TOP
o Negative result = red cells stay suspended at the BOTTOM of the vial
Immune antibodies vs naturally occurring antibodies
o Immune antibodies are IgG
Cause a delayed transfusion reaction
Extravascular haemolysis
o Naturally occurring antibodies are IgM
Cause an immediate intravascular haemolysis
How do you screen a patient’s plasma for antibodies against RBC
• Antibody screen on patient’s plasma
o (1) use 2 or 3 reagent RBCs containing all important RBC antigens between them
o (2) incubate patient’s plasma and screening cells using the Indirect Antiglobulin Technique (IAT)
Indirect Antiglobulin Technique (IAT)
Patient serum containing specific antibody added to reagent RBCs
IgG antibody can attack to RBC antigens
Add Anti-Human Globulin (AHG) to promote agglutination between the IgG antibodies on the different RBC
If +ve, reaction creates bridges between RBCs coated in IgG antibodies visible clumps
Takes 30 mins incubation at 37oC
What are the two types of serological crossmatch and how are they carried?
• Serological crossmatching checks the blood against the donor’s blood specifically
o Full Crossmatch (uses IAT (Indirect antiglobulin technique)):
Patient’s plasma is incubated with donor red cells at 37oC for 30-40 mins
Detects antibody-antigen reaction that destroys the RBCs leading to extravascular haemolysis
IgG antibodies bind to RBCs but do not crosslinking add antiglobulin reagent to cause cross-linking
Agglutination/haemolysis = incompatible
o Immediate Spin [emergency scenario only]:
Saline, room temperature
Incubate patient’s plasma and donor red cells for 5 minutes only and spin
Will only detect ABO incompatibility
IgM anti-A and/or anti-B bind to RBCs, fix complement and lyse the cell
the 3 pillars of patient blood management
• Optimise haemopoiesis o Identify anaemia pre-surgery + treat IV/ PO iron – 1mg IV B12 replacement – 1mg IM hydroxocobalamin Folate replacement – 5mg PO EPO SC – preparation dependent
o Targets Ferritin 100ug/L TSATs 25-30% B12 >350 ng/L Serum folate >5 ug/L
• Minimise blood loss and bleeding o Stop anticoagulation/antiplatelet agents o Tranexamic acid – 1mg PO/IV o Blood sparing techniques o Call salvage o Prevent wastage
• Harness and optimise physiological tolerance of anaemia
o Optimise cardiac output
o Restrictive transfusion threshold for patients who are fit and healthy (Hb <80g/L)
• (avoid hypothermia, DIC/coagulopathy, electrolyte imbalance)
Which blood components need to be matched for both ABO + D?
Which blood components need to be matched only for ABO?
ABO + D
RBC
Plt
Only ABO
FFP
Cryoprecipitate
Storage of
RBC
Plt
FFP
Cryoprecipitate
RBC
4C for 35 days
if outside of fridge for >30min goes to the bin – worried about bacterial contamination
Complete transfusion should take place within 4h of leaving the fridge
Plt
20C (room temperature) for 7 days
Screened for bacteria before release
Transfuse over 20 mins
FFP
Frozen (-25C)
Once thawed can be kept at 4C for 24 hours
Cryoprecipitate
Frozen
Once thawed has to be kept at room temperature and use within 4 hours
What should happen if a patient develops temperature during a plt transfusion?
?bacterial contamination of platelets
stop the platelets
take blood cultures
send platelets back to the lab for microbiological testing
Most likely cause if a patient reacts when FFP/cryoprecipitate is being transfused?
• A reaction with plasma is more likely to be allergic as plasma is frozen and so is unlikely to be contaminated by microbes
RBC transfusion
What should happen before?
How often should Hb levels be checked?
By how much g/l does 1 unit of RBC raise Hb?
• Treat iron/folate/b12 deficiency first unless active bleeding
• Check Hb
o Pre-transfusion
o After every 1-2 units
• 1 unit RBC = Hb increment of 10g/L in a 70-80 kg patent (if the patient is not haemolysing)
o Only transfuse one unit at a time unless active bleeding
o Can be transfused “stat” but routinely would be 2-3h
Hb targets in RBC transfusion depended patients
70 g/l if asymptomatic, 80 g/l if symptomatic
o Higher threshold of up to 90-100 g/l for patients with CHD
o Transfusion to >100g/L rarely required unless
Symptomatic (IHD, SOB, ECG changes)
Severe cardiac/respiratory disease
Triggers for the following RBC transfusion indicators
Major blood loss
Pre-op, Critical care
Post chemo
Major blood loss
>30% of blood volume lost
Pre-op, Critical care
<70 or 80 g/l depending on co-morbidities
Post chemo
<80 g/l
Plt transfusion
By how much does 1 unit of plt raise plt count?
• 1 unit of platelets in an adult treatment dose usually raises platelet count by 30-40 x 109/L
Plt transfusion contraindications
o HITT (heparin-induced thrombocytopenia with thrombosis) – patients who have had a clot on UFH o TTP (thrombotic thrombocytopenic purpura)
Triggers for the following plt transfusion indicators
Massive transfusion Prevent bleeding (surgery) Prevent bleeding (post-chemo) Platelet dysfunction or immune cause Reduced platelet production (e.g. leukaemia
Platelet dysfunction can be caused by drugs (e.g. aspirin, clopidogrel)
)
Massive transfusion
Aim plt >75 x 10^9/L
Prevent bleeding (surgery)
<50 x 10^9/L
<100 x 10^9/L - if critical site - eye, CNS, polytrauma
Prevent bleeding (post-chemo)
<10 x 10^9/L
<20 x 10^9/L if sepsis
Platelet dysfunction or immune cause
Reduced platelet production (e.g. leukaemia
Only if active bleeding
FFP
What should happen before?
When should FFP be transfused?
Adult dose
when and how do you assess the effectiveness of the transfusion?
- consider using vitamin K first if appropriate
- Do not use unless patient is bleeding or undergoing a procedure e.g. surgery
Adult dose - 15-20 ml/kg
• Reassess after administration by measuring coagulation parameters
What does FFP consist of?
Contains all the clotting factors
FFP indications
Massive transfusion
Aim to maintain PT and APTT ratio at <1.5
Early infusion of FFP is recommended to treat coagulopathy
Liver disease
PT ratio >1.5
Replacement of a single coagulation factor deficiency e.g. factor V
DIC
In the presence of bleeding, abnormal coagulation results, or if the patient needs a procedure
TTP – thrombotic thrombocytopenic purpura
Treatment of choice for reversal of warfarin
PCC (F 2, 7, 9, 10)
Prothrombin complex concentrate
What is cryoprecipitate
Adult dose
children dose
transfusion indications
Fibrinogen + Fibronectin F8, F13, VWF plt microparticles IgA Albumin
essentially raising fibrinogen by 1g/L
- Adult dose – 15-20ml/kg – 2 pools (10 donors)
- Children dose – 5-10 mls/kg
- Bleeding associated with hypofibrinogenemia Fibrinogen <1g/litre Seen in Liver disease DIC
- Dysfibrinogenemia
Indications for
CMV negative blood -
Irradiated blood
Washed red cells and platelets
CMV negative blood - only required for intra-uterine /neonatal transfusions and
for elective transfusion in pregnant women (baby in-utero is exposed to maternal
transfusion)
• Irradiated blood - highly immunosuppressed patients, who cannot
destroy incoming donor lymphocytes: which can cause (fatal) transfusion
associated graft versus host disease (TA-GvHD)
• given to patients who have severe allergic
reactions to some donors’ plasma proteins
A- RBC can be given to
A-
A+
AB-
AB+
Major haemorrhage mx
- 1g tranexamic acid (except in GI bleeds – no benefit)
- O -ve blood
• Use plasma products first/early
o Best use of blood : FFP is 1:1
o Early use of cryoprecipitate + platelets is recommended to prevent coagulopathy
- Send x2 transfusion samples ASAP so group specific blood can be issued
- Consider use of fibrinogen concentrate 50mg/kg if >4 units of blood transfused
Commonest blood type
O+
Indications for O+ emergency transfusion
emergency for females >50 years of age and for most males >18 years of age
Indications for O- emergency transfusion
- Given to patients of childbearing potential
* Given to patients who can only have O- blood
How often do you monitor a patient during a transfusion for an acute transfusion reaction?
Baseline temperature, pulse, RR, BP before transfusion
Repeat after 15 mins (most reactions start within 15 mins)
Repeat hourly
Repeat at the end of the transfusion
0m 15m 1hr 1hr… end
Describe Febrile Non-Haemolytic Transfusion Reaction (FNHTR)
Mild/Moderate
• Occurs during/soon after transfusion (blood or platelets)
• Rise in temperature by around 1 degree, chills and rigors
• No circulatory collpase
• Common before blood was leucodepleted (now rarer)
• Tx:
o Transfusion stopped or slowed
o Treat with paracetamol
- Caused by the release of cytokines from white cells during storage
- Prevented by leukodepletion
Mx of Allergic Transfusion Reaction
What is it caused by?
o Transfusion usually stopped or slowed
o IV antihistamines
o In future transfusions, give prophylactic anti-histamines
• Caused by allergy to donor plasma proteins
ABO Incompatibility / Wrong Blood
Mx
Ig__ mediated
What kind of haemolysis
main sx
o Stop transfusion – check patient/component
o Bloods
o Discuss with haematology doctor ASAP
IgM mediated
INTRVASCUAR haemolysis
o General: restless, chest/loin pain, fever, vomiting, flushing, collapse, haemoglobinuria (later)
o Monitoring: Low BP, high HR, high Temperature (>2oC)
How does a transfusion reaction to bacterial contamination present?
Order of likelihood of contamination
• Presents similarly to ABO mismatch
o General: restless, fever, vomiting, flushing, collapse
o Monitoring: Low BP, high HR, high Temperature (>2oC)
• Order of likelihood of contamination: o Platelets (stored at room temperature) > RBCs > frozen components
What blood products should patients with IgA deficiency be given?
In these patients you need to give them washed products or IgA deficient products
Respiratory complications of transfusion - most common to least common
all of them are acute
Transfusion associated circulatory overload (TACO) > Transfusion associated dyspnoea (TAD) > Transfusion related acute lung injury (TRALI)
How does TACO present, in which patients and what can you do to prevent it?
• Majority present within 6 hours of transfusion
• Pulmonary oedema/fluid overload
o Clinical features – SOB, low SaO2, high HR, high BP
o High JVP, high PCWP (pulmonary capillary wedge pressure)
o CXR – fluid overload/cardiac failure
• Often caused by lack of attention to fluid balance – especially in
o Cardiac failure, renal impairment, hypoalbuminaemia, liver disease, those on fluid replacement very small/young/old
• Tx
o Assess patient – look at their fluid balance
o You need them to be neutral balance if you are going to transfuse them
o Might need to give them some diuretics to create that space
How does TRALI present and why does it happen?
• Looks at bit like ARDS (more common in FFP or platelet transfusion)
• Presents during/within 6 hours of transfusion
• No clinical fluid overload
• Symptoms and signs
o Clinical features – SoB, low O2 sats., high HR, high BP, fever
o CXR – bilateral pulmonary infiltrates during/within 6 hours of transfusion (not due to circulatory overload and other causes)
o Absence of heart failure
• Mechanism
o Anti-WBC antibodies in donor blood (HLA or neutrophil antibodies)
o These interact with WBCs in the patient
o Aggregates of WBCs stick to pulmonary capillaries release neutrophil proteolytic enzymes and toxic O2 metabolites lung damage
• Prevention
o Use male donors for plasma and platelets no pregnancy or previous transfusions (you can’t donate if you’ve had previous transfusions), so no HLA/human neutrophil antibodies
How can CMV be removed from WBC?
Who gets CMV -ve blood?
Leucodepletion/irradiation removes CMV in WBCs (‘washing’ done for IgA deficient patients)
CMV -ve products are only given to pregnant women and neonates
Delayed haemolytic transfusion reaction
When
presents with
What kind of haemolysis
iG__ mediated
Reason
What do you need to do before the next transfusion?
- Occurs within a week
- Presents with jaundice, dark urine
- EXRAVASCULAR haemolysis
- IgG mediated
- Alloimmunisation = 1-3% of all patients transfused will develop an antibody against a RBC antigen that they lack
- Further transfusions with RBCs expressing same antigens antibodies will lyse RBCs extravascular haemolysis
• Repeat the group and screen and look for new antibodies that may have been made against the transfused red cells
What kind of antibodies are
Anti-A Anti-B Anti-Rh anti-Duffy anti-Kidd
Anti-A, Anti-B = IgM antibodies
Anti-Rh, anti-Duffy, anti-Kidd = IgG antibodies
Pathophysiology behind GVHD in blood transfusion
presentation
prevention
• Pathophysiology
o Donor’s blood will contain some lymphocytes that are able to divide
o Normally, the patient’s immune system will recognise these donor lymphocytes as foreign and destroy them
o In susceptible patients (very immunosuppressed), these lymphocytes are not destroyed
o Lymphocytes recognise patient’s tissue HLA antigens as foreign and attack (attack gut, liver, skin and bone marrow)
• Clinical features o Diarrhoea o Liver failure o Skin desquamation o Bone marrow failure o Death
• Prevention
o Irradiate blood components for very immunocompromised patients and patients who get have HLA-matched components
Post transfusion purpura
when does it happen
why
who does it affect
mx
- 7-10 days after transfusion of blood or platelets
- Due to very low platelets (<20 x 109/L) Can cause life-threatening bleeding
- Affects HPA-1a (Human Platelet Antigen) negative patients with anti-HPA 1a antibodies - HPA 1a -ve patients previously immunised via pregnancy or transfusion
- Exact mechanism is unknown
• Tx:
o IVIG infusion
How is the fetus monitored for anaemia during pregnancy?
MCA doppler US
How does anti-D work?
The RhD +ve cells of the foetus will get coated by the exogenous anti-D immunoglobulin
They will then be removed by the mother’s reticuloendothelial system (spleen) before they can sensitise the mother to produce anti-D antibodies
For this to be effective, the anti-D injection must be given within 72 hours of the sensitising event
When do you do a Kleihauer test?
if >20w gestation and at delivery
to determine if more anti-D is needed than the standard dose if the foetal bleed is large [determines for how many ml of blood we need to give anti-D]
What is RAADP?
o Routine antenatal anti-D prophylaxis (RAADP)
~1% of pregnancies have no obvious sensitising events yet RhD negative mothers become sensitised
To prevent this, routine anti-D prophylaxis can be given:
• 1 large dose (1,500IU) at 28w
• 2 smaller doses (500, 500 IU) at 28w and 34w
How many units are needed to prevent sensitisation from 1 ml of FMH?
125 IU
for other quantities of FMH multiply appropriately
