Theme 7 Haemotology: Blood transfusions Flashcards
Name all the blood components available for transfusion?
- Red blood cells
- Platelets
- Plasma
- fresh frozen plasma
- cryoprecipitate
- fractionation (factor concentrates, albumin, immunoglobulin)
Explain the process of filtering blood after it is taken and before it is donated
- Leucodepletion –> removal of WBCs from the blood thats being donated as they can carry infection and lead to transfusion reaction
- Blood is separated into its constituent parts –> RBCs, platelets and plasma
- Plasma can either be frozen or cryoprecipitated
What is cryoprecipited?
plasma is frozen and then defrosted at 4 degrees
What is the most commonly transfused blood product?
1 unit of RBC
1 unit of RBC has a haematocrit of what %?
60%
What is haematocrit?
the ratio of the volume of red blood cells to the total volume of blood
How are red blood cells for transfusion kept healthy during storage?
plasma is replaced by a solution of electrolytes, glycose and adenine to keep the red cells healthy
1 unit transfusion is expected to raise Hb by how much?
10g/L
What is:
- the Therapeutic dose of 1 unit of RBC
- Usual transfusion time
- 10-20 ml/kg
2. 1.3-3hrs
What 4 situations do NICE Guidance state transfusion is suitable?
- Bleeding
- Anaemia with severe symptoms
- Acute anaemia with mild symptoms
- Chronic anaemia with symptoms
For platelet transfusion, what is?:
- Adult therapeutic dose
- Platelet count per dose
- Shelf life
- Usual transfusion time
- 4-6 donations
- 3x10^11
- 5 days
- 20-30 mins/unit
How many units of platelets are produced from a unit of whole blood, and how many of these units are pooled together in a pack?
- 1 unit is produced from a unit of whole blood
- 4-6 of these units are pooled together in a single pack
What are apheresis platelets?
- platelets are removed through an apheresis machine that collects platelets and return all other blood constituents to the donor
- selectively removes platelets
Why do we transfuse platelets?
-to treat OR prevent bleeding due to severe thrombocytopenia or platelet dysfunction
What is thrombocytopenia?
low platelets
In what conditions should you not give platelets?
- immune thrombocytopenic purpura
- thrombotic thrombocytopenic purpura
- heparin induced thrombocytopenia
What does fresh frozen plasma (FFP) contain?
all clotting factors
For FFP, what is:
- Volume of 1 unit
- Usual tranfusion time
- Therapeutic dose
- 300ml
- 30 mins/unit
- 12-15 mL/kg
Why would we transfuse FFP?
- to replace clotting factors in patients with multiple factor deficiencies
2. to treat bleeding in patients with abnormal clotting
When should we NOT transfuse FFP?
- to treat single factor deficiencies where a factor concentrate is available e.g haemophilia A when you’re deficient in factor 8 we can just give factor 8
- to correct abnormal clotting in patients that are not bleeding or having procedures
- to reduce warfarin
How does warfarin work?
it inhibits clotting factors II, VII, IX and X so patients on warfarin are deficient in these clotting factors
What is best to reverse warfarin? (much better than FFP)
prothrombin complex concentrate
What is cryoprecipitate and what does it contain?
- FFP defrosted at 4 degrees and the liquid that melts off is the cryopreciptate
- contains fibrinogen, von willebrand, factor VIII and factor XIII
For cryoprecipitate, what is:
- Therapeutic dose
- Storage
- Shelf life
- Volume per unit
- Max transfusion time
- 10-15ml/kg
- -30 degrees
- 3 years
- 15ml
- STAT
What is cryoprecipitate mainly used for?
as a concentrated source of fibrinogen in acquired coagulopathies i.e massive haemorrhage, DIC, liver failure –> ONLY if the patient is bleeding
What are the 4 non-immunological complications of tranfusion?
- Transfusion transmitted infections (TTI)
- Transfusion Associated Circulatory Overload (TACO)
- Febrile non-haemolytic transfusion reaction (FNHTR)
- Iron overload
Which infections is every blood donation now tested for?
HIV, HBV, HCV, HTLV and syphillis
Why does FNHTR occur?
FNHTR are due to cytokines or other biologically active molecules that accumulate during storage of blood components
What are the signs and symptoms of TTI?
- Rigors
- high fever
- severe chills
- hypotension
- nausea
- vomiting
- dyspnoea
- circulatory collapse
What are the clinical features and treatment of FNHTR?
Clinical features:
- rise of temperature > 1 degree from baseline
- rigors
- tachycardia
Treatment:
-is mild so paracetmol
What are the signs and symptoms of TACO?
- dyspnoea
- orthopnoea
- tachycardia
- hypertension
- hypoxemia
- raised BP
- elevated jugular venous pulse
What are the risk factors for TACO?
- elderly patients
- small children
- LVF, renal impairment, low albumin, fluid overload
- large transfusion volume
- increased rate of transfusion
How do we treat TACO?
O2, diuretics, monitor fluid balance
What is ABO incompatibility?
when a mother’s blood type is O, and her baby’s blood type is A or B. The mother’s immune system may react and make antibodies against her baby’s red blood cells.
What are the 6 immunological complications?
- Acute haemolytic transfusion due to incompability
- Delayed haemolytic reaction
- Post transfusion purpura
- Allergic / anaphylactic reaction
- TRALI (transfusion related acute lung injury)
- TA-GvHD (transfusion associated graft-versus-host disease)
What is acute haemolytic reaction?
- due to transfusion of RBC to a recipient that has pre formed antibodies against antigens that are expressed on the transfused RBC
- usually due to the patient being given the wrong blood group
- most often ABO incompatibility
What are the signs and symptoms of acute haemolytic reaction due to incompatibility?
- fever and chills
- back pain
- infusion pain
- hypotension
- haemoglobinuria
- increased bleeding (DIC)
- chest pain
- sense of “impending death”
What is cross matching?
patients plasma is mixed with donor red cells to see if a reaction occurs
If there is a reaction, RBC units are incompatible and there is a risk of acute haemolysis
If there is no reaction, RBC units are compatible and there is no risk of acute haemolysis
How do we try to prevent acute haemolytic reaction?
“Group+screen”:
- Pre-transfusion testing on patients
- determination of ABO of Rh (D) group
- test patient’s plasma for antibodies
- if positive: antibody identification
- if negative: no further testing
Which test do we use for RBC transfusions?
Compatibility testing “cross matching”:
-donor red cells of the correct ABO and Rh group are selected
What is cross matching?
patients plasma is mixed with donor red cells to see if a reaction occurs
If there is a reaction, RBC units are incompatible and there is a risk of acute haemolysis
If there is no reaction, RBC units are compatible and there is no risk of acute haemolysis
What is DAT
Direct anti-globulin test to detect antibodies bound on RBC
agglutination = positive reaction
no agglutination = negative reaction
when is the onset of the delayed haemolytic reaction?
3-14 days following a transfusion of RBC
What are the clinical features of delayed haemolytic reaction?
fatigue
jaundice
and / or fever
Why do allergic reactions in transfused patients occur?
due to hypersensitivity of recipient of transfused “random” proteins
What are the clinical features of allergic reactions due to transfusion
- rash
- urticaria
- pruritus
- wheeze
- +- rigors / fevers
What is the treatment of allergic reactions?
antihistamines, steroids
Which patients are at higher risk of a transfusion associated anaphylactic reaction?
patients with IgA deficiency and anti-IgA antibodies
What is TRALI?
- Transfusion related acute lung injury
- antibody in blood product attacks the WBCs of the patient
- the WBC becomes activated and lodge in the pulmonary blood vessels and cause inflammation in the lungs
- serious complication of transfusion
How can you distinguish between TACO and TRALI?
- High BP in TACO
- Low BP in TRALI
- TACO gets better with diuretics because its a fluid overload
- TRALI will be worse with diuretics
How long until the onset of “acute lung injury” in TRALI?
occuring within 6 hours of a transfusion
What are the symptoms of TRALI?
low BP, fever, neutropenia
