CP7-2 transfusion medicine Flashcards
When was the first unpublished blood transfusion by Philip Physick?
1795
When was the first published blood transfusion by James Blundell?
1818
Why is leucodepletion done?
To separate the red blood cells from whole blood
What different forms can plasma be given?
As fresh frozen plasma
As cyroprecipitate
As components from fractionation of blood e.g. factor concentrates, albumin and immunoglobulins
How much have RBC transfusions been reduced by in the last decade?
10%
How much has platelet transfusion increased by in the last decade?
5%
How much has the donor pool shrunk by in the last decade?
15%
What board sets guidelines on transfusions?
NICE
What are the characteristics of 1 unit of RBC?
Concentrated red cells with most plasma removed
Plasma replaced by solution of electrolytes, glucose and adenine
Has a haematocrit of 60%
Raises Hb by 10g/L
Contains approximately 200-250,g of iron
Stored at 4 degrees Celsius for up to 35 days
Volume = 280 +/- 60 ml
Transfusion time = 1hr 30 mins - 3 hrs
4h limit from removal of cold storage to end of transfusion
What shouldn’t be prescribed alongside a RBC transfusion?
Iron
What is the therapeutic does of RBC transfusion?
10-20 ml/kg of recipient
When do NICE suggest RBC transfusion?
Bleeding - amount dependent on amount lost
Anaemia with severe symptoms - until symptoms resolve but no more than 100g/l
Anaemia with moderate symptoms - <70 g/L for patients without CVD and <80 g/L for patients with CVD
Chronic anaemia - amount base on individual transfusion plan
What are causes for anaemia should not be treated with transfusion?
Iron deficiency
B12 and folate deficiency
Renal disease that can be treated with erythropoietin treatment
What disease can cause chronic anaemia?
Sickle cell
What are two types of platelet transfusions?
Pooled platelets
Apheresis platelets
What are pooled platelets?
4-6 x 1 unit of platelets collected from different donors pooled together
What are aphresis platelets?
Platelets removed from a donor via an aphresis machine by collecting the platelets and returning all other blood constituents to the donor
What is the benefit of pooled platelets?
Less allergic reactions as contain less plasma
What is a benefit of aphresis platelets?
In theory there is less exposure to infective agents as platelets come from one donor
What are characteristics of a platelet transfusion?
stored at room temp (22 degrees C)
shelf life = 5 days post collection
volume = 250-350ml
usual transfusion time = 30 mins/unit
Who is given a platelet transfusion?
To treat bleeding in patients with thrombocytopenia or platelet dysfunction
To prevent bleeding in these patients
What dose of platelet transfusion is given to treat patients with a massive haemorrhage?
enough to maintain a platelet count of >50 x 10^9/L
What dose of platelet transfusion is given to treat patients with critical site bleeding?
enough to maintain a platelet count of >100 x 10^9/L
What dose of platelet transfusion is given to treat patients with clinically significant bleeding?
enough to maintain a platelet count of >30 x 10^9/L
What dose of platelet transfusion is given to treat patients with bone marrow failure?
<10 x 10^9/L or <20 x 10^9/L if additional risk e.g. of sepsis
What dose of platelet transfusion is given to treat patients to prevent prophylaxis for surgery?
most major surgeries = 10 x 10^9/L
CNS or eye surgery = <100 x 10^9/L
What are contraindications for plasma transfusions?
immune thrombocytopenic purpura
thrombotic thrombocytopenic purpura
heparin induced thrombocytopenia and thrombosis
What are characteristics of fresh frozen plasma transfusions?
Contains all clotting factors at physiological levels
Therapeutic dose = 12/15 ml/kg (4-6 units for average adult)
stored at -30 degrees C for up to 3 years
1 unit = 300ml
usual transfusion time = 30 mins/unit
thawed immediately before use for 20-30 minutes
levels of factors V and VIII begin to diminish 6 hours after thawing
When is a fresh frozen plasma transfusion given?
for patients with multiple factor deficiencies:
to treat significant bleeding in patients with abnormal clotting results
to correct abnormal clotting results prior to invasive procedures.
When should fresh frozen plasma never be transfused?
To treat single factor deficiencies
To correct abnormal clotting results in patients that are not bleeding
To reverse warfarin
How can warfarin anticoagulation be reversed?
With transfusion of a prothrombin complex (factor IX) concentrate
What does prothrombin complex concentrate contain?
high concentration of vit K dependent factors = factors II, VII, IX and X
What are characteristics/properties of cryoprecipitate transfusions?
extracted from fresh frozen plasma during the thawing process.
contains fibrinogen, von Willebrand factor, factor VIII and factor XIII
therapeutic dose = 10-15 ml/kg (6-10 units for normal adult)
volume per unit = 15 ml
maximum transfusion time = stat
What is cryoprecipitate transfusion used to treat according to NICE?
To maintain fibrinogen to prevent or treat bleeding
When is a complication of a transfusion classed as an acute reaction?
if <24 hours post transfusion
When is a complication of a transfusion classed as a delayed reaction?
if >24 hours post transfusion
What are examples of non immunological complications of transfusion?
Transfusion transmitted infections (viral/prion/bacterial) e.g. HIV, HCV or HBV infection
Transfusion associated circulatory overload (TACO)
Febrile non-haemolytic transfusion reaction (FNHTR)
Iron overload
What are the two categories of transfusion complications?
Non-immunological
Immunological
How are viral transfusion transmitted infections prevented?
By having donors fill in a questionnaire
Doing mandatory testing
What is the test for hepatitis B?
HBsAg testing
What is the test for HIV in blood donations?
Anti HIV 1 and 2 and HIV nucleic acid testing (NAT)
What is the test for hepatitis C in blood donations?
Anti HCV and HCV nuclei acid testing (NAT)
How is hepatitis E tested for in blood donations?
Hep E virus nucleic acid testing aka HEV NAT
How is human T-cell lymphotropic virus tested for in blood donations?
anti-HTLV I and II testing
How is syphilis tested for in blood donations?
checking for syphilis antibodies
What disease has there been 4 known cases of it being passed on as a transfusion transmitted infection before 1999?
variant Creutzfeld-Jakob disease (vCJD)
How has vCJD transmission via transfusion been prevented?
universal leucodepletion (since 1999)
import plasma from countries with low incidence of vCJD - no need in UK since 2019
inactivate prions with methylene blue
What symptoms will a patient present with if they have had a transfusion with bacterial contaminated components?
severe reaction - usually in first 15 minutes - of rigors, high fever, severe chills, hypotension, nausea and vomiting, dyspnoea and circulatory collapse.
How will a patient with febrile non-haemolytic transfusion reaction (FNHTR) present?
accumulation of cytokines (or other biologically active molecule) in blood during storage which cause an unpleasant reaction of fever of 1 degree +/- rigors and tachycardia when transfused. It is not life threatening and can be resolved by stopping the transfusion.
How will a patient with transfusion associated circulatory overload (TACO) present?
sudden dyspnoea
orthopnoea
tachycardia
hypertension
hypoxemia
raised BP
elevated jugular venous pulse
symptoms appear up to 24 hours post transfusion
What are some immunological complications of transfusion?
acute haemolytic transfusion reaction due to incompatibility
delayed haemolytic reaction
post transfusion purpura
allergic/anaphylactic reaction
transfusion related acute lung injury (TRALI)
transfusion associated graft-vs-host disease (TA-GvHD)
What is acute haemolytic reaction?
a severe, sometimes fatal (20-30% of the time) reaction early into transfusion (first 15 mins), or milder reaction later in transfusion due to incompatibility of transfusion. Characterised by:
fever and chills
back pain
infusion pain
hypotension/shock
haemoglobinuria
increased bleeding
chest pain
patient might have a sense of impending death
How does free Hb lead to symptoms of acute haemolytic reaction?
free Hb released into circulation when there is ABO incompatibility lead to:
- nitric oxide depletion in endothelial cells leading to vasoconstriction and angina
- endothelial cells release too many cytokines into the blood too quickly (a cytokine shower) causing fever, rigors and hypotension
- endothelial cells express pro-coagulant molecules activating the clotting cascade. This causes disseminated intravascular coagulation = bleeding.
- free Hb is deposited in the tubules of the kidney causing oxidative damage to renal cells = AKI
How may a patient with acute haemolytic reaction due to incompatibility present?
fever and chills
chest pain
back pain
infusion pain
hypotension/shock
haemoglobuniuria (high Hb in urine)
increased bleeding
patient feels a sense of impending death
How is acute haemolytic reaction due to incompatibility prevented?
by pre transfusion testing involving determination of blood group and plasma screening for antibodies.
with cross-matching for RBC transfusions (patient’s plasma mixed with some donor red cells to assess for a reaction)
What causes delayed haemolytic reactions?
Post transfusion formation of new IgG antibodies against RBC antigens other than ABO
How do patients with delayed haemolytic reaction present and what are the lab findings in these patients?
symptoms = fatigue, jaundice +/- fever
lab findings = drop in Hb, increased LDH (lactate dehydrogenase) and indirect bilirubin.
What is direct anti-globulin testing used for?
to detect antibodies bound on RBCs
How common is transfusion allergic reactions?
Common - Occurs in 1% of transfusions
What is the most common cause of allergic reaction to transfusion?
Reaction to FFP, cryoprecipitate or platelets
How will a patient with an allergic reaction to a transfusion present?
rash, urticaria (hives) and pruritus (itching)
+/- rigors and fever
periorbital oedema
How will a patient with an anaphylactic reaction to a transfusion present?
laryngeal oedema
bronchospasm
hypotension
swelling
What is transfusion related acute lung injury?
a complication of transfusion
antibodies in the transfused unit act against antigens expressed by the recipient’s leukocytes.
activated WBCs become lodged in pulmonary capillaries
these WBCs release substances that cause endothelial damage and capillary leak.
Who are at increased risk of an anaphylactic reaction to a transfusion?
Patients with IgA deficiency and anti-IgA antibodies.
What signs and x-ray findings might a patient with transfusion related acute lung injury show?
Show hypoxemia
New bilateral chest infiltrates
No evidence of volume overload
