Transfusion medicine Flashcards
Blood donations tested for?
- ABO group and RhD type
Infection
Which infections are blood donations tested for?
- HIV 1+2 abs
- Hepatitis BsAg
- Hepatitis C ab
- Syphilis ab
- HTLV ab
Processing of blood donations?
- Leucocyte depletion
- centrifuged:
- red cells
- platelets
- Plasma - Platelets sampled for
bacterial testing - Special processes (eg irradiation, washing, hyperconcentration)
Plasma centrifuged to which components?
Fresh frozen plasma
Cryoprecipitate
Red cells in blood donations
- shelf life?
- storage temp?
- how much time once out of fridge
- 35 day shelf life
- at 4 degrees
- transfuse < 4 h after removing from fridge
2 methods of getting them platelet concentrates in blood donations?
I. Pool 4-6 donors blood
II. Apheresis
- single donor
Platelet concentrates in blood donations
- shelf time?
- storage temp
- max for 7 days
2. Storage: 22oC
Fresh frozen component in blood donations
- storage
- shelf-time
- special processing
- Plasma frozen to -30oC
- 2 yr storage
- I.Viral inactivation
-Methylene Blue
II. Solvent detergent
treatment (Octaplas)
Fresh frozen component in blood donations use?
For clotting factor replacement if bleeding
Cryoprecipitate
- how is it formed?
- use
- Precipitate that forms
when thawing FFP - Fibrinogen
When to give blood transfusion in anaemia?
If below Hb < 7g/dL
acute haemolytic transfusion reaction timing?
are defined as fever and other symptoms/ signs of haemolysis within 24 hours of transfusion
acute haemolytic transfusion reaction types?
I. transfusion-related acute lung injury (TRALI),
II. transfusion-associated circulatory overload (TACO),
III. transfusion-associated dyspnoea (TAD)
acute haemolytic transfusion reaction sx?
Fever, renal failure
Donor PLASMA compatibility: (also same with Platelets, FFP, cryoprecipitate)
Different from RBC compatibility A receives from A or AB B receives from B or AB O receives from any AB receives from AB
Blood clotting pathway (haemostasis)
- Collagen and tissue factor exposed
- Von Willebrand Factor binds collagen
- Platelets adhere to vWF-collagen
- Platelets activate and aggregate
- Tissue factor initiates rapid thrombin generation on activated platelets
- Thrombin converts fibrinogen to fibrin and
completes platelet activation - Stable fibrin-platelet clot is formed
How TF (tissue factor) initiates rapid thrombin generation on activated platelets
by causing release of Proteases FVII, FX, FIX, FXI and Co-factors FVIII and FV
3 regulations of haemostasis
- vWF activity is regulated by ADAMTS 13
- Thrombin is regulated by Antithrombin and Activated protein C
- Fibrin cleaved by Plasmin into fibrin degradation products (D-dimer)
2 types of clinical disorders of haemostasis?
- Primary haemostasis disorders
- Coagulation pathway disorders
Primary haemostasis disorders cause?
- defects in
Platelets,
VWF,
vessel wall
Primary haemostasis disorders sx?
- mucocutaneous bleeding eg epistaxis, purpura
- immediate bleeding
Coagulation pathway disorders causes?
- defects in:
- Coagulation factors
- fibrinogen
Coagulation pathway disorders presentation
- deep tissue bleeding (joints)
- delayed bleeding (weak clot forms and breaks, followed by secondary bleeding)
Both can cause GI/CNS bleeds
Laboratory investigations of bleeding?
1. Platelet count + blood film Indicates platelet number (not function) 2. Coagulation screen I. PT time II. aPTT time
PT time?
Prothrombin time (PT) Time to fibrin clot formation
aPTT time?
Activated partial thromboplastin time (aPTT)
Time to fibrin clot formation
PT time result interpretation?
Detects abnormal
FVII, (extrinsic pathway)
FX, FV, FII, Fibrinogen (common pathway)
aPTT time result interpretation?
Detects abnormal
FVIII, FIX, FXI (intrinsic factors)
FX, FV, FII, Fibrinogen (common pathway)
How long Group and Save takes?
- takes 40 mins
Group and save procedure?
- perform Indirect Antiglobulin Test
screening and store sample - request this if blood might be needed but not inevitable.
how long Crossmatch takes
5-40 mins
Cross-match involves?
- laboratory will assign units for specific patient
- 5 minutes if recent group and save
- 40 mins if antibodies/no previous G+S (IAT crossmatch)
Acute haemolytic transfusion reactions (AHTR) diagnosis?
confirmed by one or more of the following:
• a fall of Hb
• rise in LDH
• positive direct antiglobulin test (DAT)
• positive crossmatch
Delayed haemolytic transfusion reactions (DHTR) def?
are defined as fever and other symptoms/ signs of haemolysis more than 24 hours after transfusion
Delayed haemolytic transfusion reactions (DHTR) confirmed by? ?
- a fall in Hb or failure of increment
- rise in bilirubin
Transfusion-related acute lung injury (TRALI)
- SOB
- hypoxia
- bilateral pulmonary infiltrate
within 6 hours of transfusion
TRALI diagnosis?
any 4 of:
- high HR
- high BP
- Pulmonary oedema
- Fluid retention
- respiratory distress
Transfusion-associated dyspnoea (TAD)
- respiratory distress within 24 hours of
transfusion that does not meet the criteria for TRALI, TACO or allergic reaction.
what blood component mostly affected during transfusion?
IRON
• 1 unit red cells contains ~250mg iron
• Maximum iron excretion ~3mg/day
which organs are in danger of iron overload post transfusion?
heart liver pancreas joints pituitary
Main cause of iron overload
Regular transfusion (several years) -iron overload
Management of iron overload
• minimise transfusion
• long term iron chelation (desferrioxamine [s/c] or deferasirox /
deferiprone [oral] )
Transfusion associated circulatory overload (TACO) sx?
raised pulse & BP at 15 mins post transfusion
Transfusion associated circulatory overload (TACO) mx?
Slow down the infusion and give frusemide.
Major haemorrhage def?
- 50% of total blood volume lost in less than 3 hours
- Loss of more than one blood volume within 24 hours
(around 70 mL/kg, >5 litres in a 70 kg adult)
Major haemorrhage primary management?
tranexamic acid bollus for 10 min followed by 8 hours iv infusion
