Transfusion

Question 1

What are the various blood products?

Answer 1

• Packed red cells
• Platelet rich plasma
• Platelet concentrate
• Fresh frozen plasma
• Cryoprecipitate
• SAG-Mannitol Blood

Question 2

What do we use packed red cells for?

Answer 2

Concentrated red cells (packed cells) in a suspension of SAGM, obtained by centrifugation of whole blood, used for:

• Symptomatic anaemia
• Exchange transfusion
• Radiotherapy
• If significant bleeding anticipated, activate major haemorrhage protocol

1 unit increases Hb by 10-15g/L

Question 3

What are the Hb transfusion thresholds for red blood cells (before and after)?

Answer 3

• Transfusion threshold → 70g/L (or 80g/L in pts w/ ACS)
• Target after transfusion → 70-90g/L (80-100g/L in pts w/ ACS)

Please note that these thresholds should not be used in patients with ongoing major haemorrhage or patients who require regular blood transfusions for chronic anaemia. Also, in a non urgent scenario, a unit of RBC is usually transfused over 90-120 mins.

Question 4

What do we use Fresh Frozen Plasma for?

Answer 4

• FFP contains all coag factors, albumin and immunoglobulin
• Prepared from single units of blood
• Given for clotting defects (eg. DIC / Warfarin OD / Liver disease)
• Unit = 200-250ml; usual dose = 12-15 ml/kg-1
• Should not be used as first line therapy for hypovolaemia
• Expensive and carries all risks of blood transfusion

Question 5

What do we use platelets for?

Answer 5

• Platelet rich plasma → administered to pts who are thrombocytopaenic and are bleeding or require surgery, it is obtained by low speed centrifugation
• Platelet concentrate → prepped by high speed centrifugation and administered to patients w/ thrombocytopaenia

Usually only needed if bleeding or blood count is <20x10⁹L or if surgery is planned, get advice if count is <100x10⁹L

Question 6

What do we use cryoprecipitate for?

Answer 6

• Formed from supernatant of FFP
• Rich source of factor VIII and fibrinogen
• Allows large concentration of factor VIII to be administered in small volume
• Typically 15-20ml
• Most suited for pts ‘clinically significant’ but without ‘major haemorrhage’ who have a fibrinogen conc <1.5g/L

Question 7

What questions need to be thought about before prescribing a transfusion?

Answer 7

• Is the lab result recent? (Hb)
• Have you reviewed the clinical condition of your patient?
• Is there an appropriate alternative to transfusion?
• Does pt have mental capacity to make informed decision regarding transfusion?
• Obtained verbal consent?
• Documented decision on rationale for transfusion?

Consent constitutes: informed, risks/benefits, verbal, documented, discharge summary

Question 8

What is the dosing for patient body weight?

Answer 8

• Assume increment of 10g/L per unit in a 70kg patient
• Always consider the size of the patient

Question 9

What is the two sample rule at SGH?

Answer 9

• 1 sample → patient known to SGH with historical blood group
• 2 samples → from discrete phlebotomy episodes for new patients

We will not delay blood in an emergency

Question 10

What is ‘Wrong blood in tube’ (WBIT)?

Answer 10

• Blood taken from wrong patient OR blood taken from right patient but labelled incorrectly
• Never event

Question 11

What obs need to be recorded for transfusion?

Answer 11

• Temp, BP, pulse, resp rate
  
  • <1hr pre-transfusion
  • at 15 mins
  • at end (usually 2-3hrs)

Question 12

What is a massive blood transfusion?

Answer 12

• Defined as replacement of an individual’s entire blood volume (>10U) within 24hrs
• Complications → ↓ platelets / ↓ Ca / ↓ Clotting factors / ↑K / hypothermia
• In acute haemorrhage, use crossmatched blood if possible, but if not then use ‘universal donor’ group O Rh -ve blood

Question 13

How do you transfuse patients with heart failure?

Answer 13

• If Hb <50g/L with HF → transfuse w/ packed red cells
• Aim to restore Hb to safe levels eg. 60-80g/L - do with care!
• Give each unit over 4h + furosemide (40mg slow IV) with alternative units
• Check for increased JVP and basal lung crackles

Question 14

What are the acute (<24hr) complications of transfusion?

Answer 14

• Acute haemolytic reactions → ABO-incompatible blood
• Anaphylaxis → pts w/ IgA deficiency + have anti-IgA antibodies
• Bacterial contamination
• Febrile reactions → Abs react w/ white cell fragments in blood product
• Fluid overload
• Transfusion-related acute lung injury (TRALI) → non-cardiogenic pulm oedema 2^o to ↑vasc permability caused by host neutrophils, activated by substances in donated blood
• Transfusion-associated circulatory overload (TACO) → excessive rate of transfusion, pre-existing heart failure

Question 15

What are the delayed (>24hr) complications of transfusion?

Answer 15

• Infections (eg. Hep B/C)
• Iron overload
• Graft versus host disease (GVHD)
• Post-transfusion purpura: potentially lethal fall in platelet count 5-7d post-transfusion

Question 16

Acute haemolytic transfusion reaction results from a mismatch of blood group (ABO) which causes massive intravascular haemolysis. This is usually the result of red blood cell destruction by IgM-type antibodies.

What are the clinical features and management of an acute haemolytic reaction?

Answer 16

• Sx → Agitation, fever, hypotension, flushing, abdo + chest pain, DIC, renal failure
• STOP transfusion
• Check identity and name on unit
• Tell haematologist
• Send bloods: FBC / U+Es / Clotting / Cultures + urine
• Keep IV line open w/ 0.9% saline

Question 17

Allergic reactions to blood transfusions are caused by hypersensitivity reactions to components within the transfusion. For allergic reactions (urticaria, itching) treat with chlorphenamine 10mg slow IV/IM and close monitoring.

What are clinical features and management of anaphylaxis?

Answer 17

• Sx → bronchospasm, cyanosis, hypotension, soft tissue swelling
• Permanently discontinue transfusion
• IM adrenaline
• Maintain airway + oxygen
• Antihistamine, corticosteroids + bronchodilators
• Contact anaesthetist

Question 18

What are the clinical features and management of bacterial contamination?

Answer 18

• Sx → fever, hypotension, rigor
• STOP transfusion
• Check identity against name on unit
• Tell haemtologist
• Send bloods → FBC / U+Es / Clotting / Cultures + urine
• Start broad-spectrum ABx

Question 19

TRALI is a rare but potentially fatal complication of blood transfusion.

How do you recognise and manage TRALI?

Answer 19

• Sx → dyspnoea, fever, cough, hypoxia, CXR: ‘white-out’
• STOP transfusion
• Give 100% O₂
• Treat as ARDS
• Donor should be removed from donor panel

Question 20

TACO (transfusion-associated circ overload) is a relatively common reaction due to fluid overload resulting in pulmonary oedema. As well as features of pulmonary oedema the patient may also be hypertensive, a key difference from patients with TRALI.

How do you recognise and manage TACO?

Answer 20

• Sx → pulm oedema, hypertension
• Slow or stop transfusion
• Consider IV loop diuretic (eg. furosemide 40mg IV) and oxygen

Question 21

Non-haemolytic febrile reactions are often due to white blood cell HLA antibodies or the result of sensitisation by prev pregnancies or transfusions.

How do you recognise and manage non-haemolytic febrile reactions?

Answer 21

• Sx → shivering + fever, 30min-1hr after transfusion
• Slow or stop transfusion
• Give antipyretic (eg. paracetamol 1g)
• Monitor closely
• If recurrent, use WBC filter

Question 22

What is the risk of transmission of variant Creutzfeldt-Jakob Disease (vCJD)?

Answer 22

• Absolute risk v small, may be transmitted via blood transfusion
• Number of steps taken to minimise risk:
  
  • 1999 onwards: all donations have undergone removal of white cells in order to reduce any vCJD infectivity present
  • 1999 onwards: plasma derivatives have been fractionated from imported plasma rather than being sourced from UK donors. FFP used for children and certain age groups of adults needing frequent transfusions is also imported
  • 2004 onwards: recipients of blood components have been excluded from donating blood