Haematology-Transfusion Flashcards
What is a transfusion threshold?
Lowest conc of haemoglobin not associated with symptoms of anaemia
What are the mechanisms of adaptation to anaemia?
- Inc cardiac output & artery blood flow
- Inc O2 extraction
- Inc erythropoiesis
- Inc production of EPO
- Inc red blood cell 2,3 DPG
- Aim to stop occurrence of hypoxia
Why do anaemia patients have transfusions?
Restore O2 carrying capacity
What are the classes of haemorrhage? What would you do? Which group of people does this apply to?
-Criteria to transfuse in acute anaemia due to blood loss
-1= no transfusion, small % reduction in blood vol
-2= no transfusion, 15-30% reduction
-3= probably transfuse, 30-40% reduction
-4= transfuse, >40% reduction
Alternative= cell salvage
Describe chronic anaemia and why you would transfuse these patients
- Threshold= 80-100g
- Inherited thalassaemia
- Symptomatic-Due to myeloid failure syndromes
- Prevent end organ damage, improve QOL, suppression of endogenous erythropoiesis
Why transfuse platelets? Any contraindications?
-Bone marrow failure
-Prophylaxis
-Treat bleeding due to severe thrombocytopenia
Contra: Heparin induced thrombosis & thrombocytopenia, thrombotic thrombocytopenia purpura
When would/would not transfuse fresh frozen plasma?
Yes= massive haemorrhage, warfarin reversal, coagulopathy with bleeding, thrombotic thrombocytopenia purpura No= replacement of single factor deficiency
What is cross matching?
Patients plasma mixed with aliquots of donor red blood cells to see if they react.
Y= incompatible, risk of acute haemolysis
N= compatible
What are the risks associated with transfusions?
Acute: Immuno= ABO incompatibility, allergy/anaphylaxis, TRALI. Non-immuno= TACO, bacterial contamination, febrile non-haemoglobin transfusion reaction
Delayed: Immuno= post transfusion purpura, transfusiom graft Vs host disease. Non-immuno= transfusion transmitted infection
What are the transmittable diseases in transfusions?
- HIV
- Hep B&C
- Prion disease
What happens in an acute haemolytic reaction?
- Release of free haemoglobin into distal renal tubules causing acute renal failure
- Stimulation of coagulation leads to microvascular thrombosis
- Stimulation of cytokine storm
- Scavenger NO leads to generalised vasoC
- Hypotension/shock, fever, back&chest pain, infusion pain, sense of death, inc bleeding, haemoglobinuria
- Severe onset during transfusion
What are delayed haemolytic reactions?
- Onset 3-14 days after transfusion
- Drop in haemoglobin, inc in LDH & indirect bilirubin
- Jaundice, fatigue, +/- fever
- Positive direct antiglobin test
- Delayed haemoglobin reaction due to IgG antibodies against RBC antigens
What is transfusion related acute lung injury?
- Serious complication sudden onset
- Donor has antibodies to recipients leucocytes
- Anti HLA/HNA-> recipient WBC-> activated WBC in pulmonary capillaries
- Release substances leading to endothelial damage & capillary leak
- Supportive treatment (mild=O2, severe=ventilate)
- Hypoxemia, bilateral CXR infiltrates
What are the differences between TACO and TRALI?
TACO= any component, raised BP, normal temp, abnormal echo, diuretics improve, fluid loading worsens TRALI= plasma/platelets, reduced BP, raised temp, normal echo, diuretics worsen, fluid loading improves
What are signs, symptoms and risk factors for TACO?
- Elderly/ very young= compromised LV function
- Raised BP & elevated jugular venous pulse
- Tachycardia, Hypertension, Hypoxemia, sudden dyspnoea
