What blood can an O- and O+ person receive?
O- can only receive O-
O+ can receive both O+ and O-
No A or B can be given because the recipient will have antibodiesNegative can only receive negativeO does not have A or B antigens
How much will 1 unit of PRBCs raise the HCT by?
When are frozen red blood cells used?
Rare blood typesOccasionally - severe leukoagglutinin reactions or anaphylactic reactions
Why are the A and B antigen important in blood types?
If you lack one, you have an IgM isoantibody to it (isoagglutinin) --> complement gets activated --> rapid intravascular lysis.
Why is type O negative blood used in emergencies?What needs to be done to it?
It does not have A or B antigens, and thus can be given to anyone.
PRBCs can only be given (the plasma has to be separated out) because the donor plasma contains Anti-A or Anti-B antibodies.
Why is the Rhesus antigen important in blood typing?
Rh D antigen is highly immunogenicAnyone who receives D+ blood when they are D- will subseuqnetly make highly active anti-D antibodies that cause severe lysis of subsequent transfusions of D+ red cells or to a future rhesus positive baby
Why is anti-D given to rhesus-negative mothers?
Stops allo-immunisation by destroying any Rh-D positive fetal erythrocytes that get through to the maternal system before the mother can make her own antibodies.
Prevents haemolytic disease (rhesus disease) of the newborn.
Okay if you have an RH+ mother and an Rh- fetus
What causes haemolytic transfusion reactions?
AcuteABO incompatibility - isoagglutinin mediatedMostly due to clerical errors and mislabelled specimensRapid intravascular haemolysis - most severe usually when the patient is under anaesthesia
DelayedMinor RBC antigen discrepancies, less severe, IgG alloantibody mediates5-10 days post transfusionMost common antigens are duffy, Kidd, Kell and Rh C and E
SSxFever, chills, backache and headacheApprehension, dyspnoea and hypotensionGeneralised bleeding and oliguriaSevere: DIC, ARF due to ATN
Delayed: usually w/o SSx
Tx - hydration, maybe forced diuresis with mannitol
What is a leukoaggluttinin transfusion reaction?
Leucocyte rich blood products esp platelets cause - happens in 1-2% of transfusionFevers and chills within 12 hours postNo haemolysisResponds to panadol and dipenhydramine, steroids
Less of an issue now with leuco depletionDifferent to a hypersensitivity reaction
What is the cause of a blood product hypersensitivity reaction?
Exposure to allogeneic plasma proteins (not leukocytes)
Anaphylactic shock may develop in IgA deficient patients because of IgA antibodies in the plasma component of the donor product.
May require washed or frozen PRBCs next time.
Under what circumstances does contamination of blood products occur?
Platelets especially because they cannot be refrigerated
Gram positive contaimination will cause fever and bacteraemia but rarely sepsis.
Gram negative will cause septic shock, acute DIC and ARF due to transfused endotoxin - usually fatal.
Reduced byAseptic techniqueDiverting first few ml of donated bloodSingle donor products (instead of pooled)POC bacterial screening to discard dodgy units
Which blood products can transmit viral diseases?
All blood products can.Risk of post-transfusion viral hepatitis is very low.Leukodepletion has greatly reduced CMB transmission, possibly equivalent to CMV-screened negative blood products.
What is tranfusion graft-versus-host disease?
Usually fatal, fever, rash, diarrhea, hepatitis, lymphadenopathy and severe pancytopaenia
Usually in patients with immune defects, malignant lymphoproliferative disorders, chemo or immunotherapy, immunosuppression, old patients getting cardiac surgery
HIV alone does not increase risk
Leukodepletion doesn't avoid, need to irradiate the blood products if high risk.
What is TRALI? What causes it and how does it present?
Transfusion-related Acute Lung Injury
Allogeneic antibodies in donor plasma bind to recipient leukococyte antigens including HLA, granulocyte and monocyte specific.
Definition: Non-cardiogenic pulmonary oedema after a blood product transfusion without other explanation. Surgical and critically ill patients most susceptible.
Reduced with male only plasma, treated with supportive care.
Reduced with male only plasma, treated with supportive care.
At what platelet level is there a higher risk of spontaneous bleeds?
Life threatening bleeding?
When do you transfuse?
What do you aim for?
Life threatening bleeding?
Given when less then 10
In thrombocytopaenia pre-op patients, goal is to get the platelet count >50
What are the causes of poor platelet response post transfusion?
Fever, sepsisSplenomegalyLagre habitusLow platelet dose in transfusionPlatelet alloimmunisation from prior transfusion
Prior pregnancyPrior organ transplantationMay get alloantibodies directed at HLA antigens - can get HLA matched antigens if this is the case.
In the rare circumstance that you would have to get a granulocyte transfusion (ie failed G-CSF), what needs to happen?
Must be ABO matchedMust be irradiated to prevent lymphocyte proliferation and prevent GVHD without funcitonal harm to the granulocytes or containing platelets.
BUT not commonly used anyway
What are febrile non-haemolytic transfusion reactions mostly due to?
Recipient has antibodies to donor antigens on leukocytes (granulocytes) due to previous transfusion or pregnancy.
Leucodepletion reduces febrile non-haemolytic transfusion reactions as a result.
A 19-year-old woman presents with recent-onset of right leg swelling and pleuritic chest pain and is found to have iliofemoral thrombosis on Doppler ultrasound examination. Results of a ventilation-perfusion lung scan indicate a high probability for pulmonary emboli. She had been taking the oral contraceptive pill for the last three years but has now ceased. She is a non-smoker. There is no significant medical history and no known family history of venous thromboembolism. Which one of the following investigations for an underlying hypercoagulable state is most likely to be affected by the presence of the extensive thrombosis? A. Antiphospholipid antibody screen. B. Antithrombin level. C. Factor V and prothrombin genotype assessment. D. Activated partial thromboplastin time (APTT). E. Full blood count including blood film.
What is the mechanism of ITP?
Antiplatelet antibody to glycoprotein IIb/IIa or Ib/IX on the platelet membrane --> platelet destruction --> mucocutaneous bleeding
What is the aetiology of ITP?
Primary / idiopathicMedication related (Thiazides, penicillin, GPIIB/IIIa inhibitors (ie tirofiban, Heparin)Hep-CHIV
What is the mechanism of ITP in HIV? Hep-C?
HIV: Direct suppression of platelet production
Hep-C: Cirrhosis related splenomegaly
What are the clinical findings in ITP?
Mucocutaneous bleeding: nosebleeds, gingivaSpontaneous bruisingUsually at PLT counts <20-30
Disease specific findings if HIV or Hep-C
What are the lab findings in ITP?
Isolated thrombocytopaeniaAnaemia if they've bledExclude HIV and Hep-CBMBx for cytopaenias if over 60 or failed to respond to ITP therapy
Megakaryocyte abnormalities are not ITP
What is the treatment of ITP?
Treat when PLT <20-30 or significant bleeding
Mainstay: short course of corticosteroids however most relapse. Plus or minus IVIG or anti-D (WinRho)
Persistent plt count <30 after roids: second line treatment (anti D, IviG are both temporary), rituxmiab works in up to 50%. Splenectomy an option
Name the thrombopoietin receptor agonists
Used in chronic ITP for people who have not responded to corticosteroids, IvIG or splenectomy or in cirrhosis due to hep-C. Must be taken indefintely
What vaccinations should be administered pre-splenectomy?
Patients should receive pneumococcal, Haemophilus influenzae type b, and meningococcal vaccination at least 2 weeks before the procedure
What are the goals and management of pregnancy-associated ITP?
The goal of management of pregnancy-associated ITP is a platelet count of 10,000–30,000/mcL in the first trimester, >30,000/mcL during the second or third trimester, and >50,000/mcL prior to cesarean section or vaginal delivery. Moderate-dose oral prednisone or intermittent infusions of IVIG are standard.
How is the thrombocytopaenia of HIV and Hep-C managed?
Treatment of either infection improves platelet count in most cases
Refractory thrombocytopenia may be treated with infusion of IVIG or anti-D (HIV and hepatitis C virus), splenectomy (HIV), or interferon-alpha or eltrombopag (hepatitis C virus, including eradication).
Treatment with corticosteroids is not recommended in hepatitis C virus infection.
A 30-year-old man has previously undergone splenectomy (six months prior) for chronic idiopathic thrombocytopenic purpura (ITP). Apart from occasional bruising, there are no haemorrhagic symptoms.
His full blood examination shows: _Repeated autoimmune and viral serology remain negative.
The most appropriate management of his thrombocytopenia is:
E. Platelet count gets treated when <30 in refractory cases or if bleeding.