Haem/Transfusions Flashcards
Which blood type is the universal donor?
O-
Which blood type is the universal receiver?
AB
How is major haemorrhage defined?
- Loss of one blood volume in 24 hours
- 50% total blood volume lost in less than 3 hours
- More than 150ml/minute
What bloods should you order in a bleed before transfusing blood?
FBC
Group and save
Clotting screen
U&E
When should you think about transfusing blood?
< 30% loss (1500ml) fluids
30-40% red cell transfusion
> 40% (2L) major haemorrhage protocol
What is group and save?
Identifies patients ABO and rhesus blood group and screens blood for antibodies.
What is cross-match?
Mixing the patients blood with the blood they are going to receive to check for a reaction.
How long does group and save and cross-match take?
40 mins each
How long should one unit of blood be given over?
2 hours
How can you safely give blood to a patient who is at risk of overload?
Prescribe diuretic at same time
When might you need to give platelets?
Haemorrhagic shock
Severe thrombocytopenia <20
Low pre-op platelets < 50
What does fresh frozen plasma (FFP) contain?
Clotting factors and plasma proteins.
When is FFP given?
Major haemorrhage (every 2 packs of red cells)
DIC
Liver disease haemorrhage
TTP
What does cryoprecipitate contain?
Fibrinogen, vWF, factor VIII, fibronectin.
When is cryoprecipitate given?
LOW FIBRINOGEN:
Massive haemorrhage
VW disease
DIC with low fibrinogen
List 6 complications of blood transfusion.
Infection transmission
Overload
Transfusion related acute lung injury (TRALI)
Haemolytic reaction
Allergic reaction
Febrile non-haemolytic transfusion reactions
What blood tests can confirm haemolytic reaction to blood products?
Coombs test positive
Hyperbilirubinaemia
What are signs of haemolytic transfusion reaction?
Pyrexia Dyspnoea and wheezing Loin pain Hypotension DIC with bruising Acute oliguric renal failure
What are causes of macrocytic anaemia?
Vitamin B12 deficiency Folate deficiency Myelodysplasia Liver disease Hypothyroidism Alcohol
What are causes of normocytic anaemia?
Primary bone marrow failure - rare: aplastic anaemia Secondary bone marrow failure: • Anaemia of chronic disease • Combined haematinic deficiencies • Uraemia
What blood tests can you do if you suspect haemolysis?
FBC (reticulocytes) Blood film - spherocytes, schistocytes Bilirubin LDH Haptoglobin Direct coombs test
What might you suspect if you see macrocytosis with hyperhsegmented neutrophils?
B12 or folate deficiency
Myelodysplasia
Where is B12 absorbed?
Terminal ileum
What tests would you do to investigate anaemia?
FBC, U&E, LFTs B12, folate, ferritin Blood film TFTs Serum immunoglobulins Urine bence jones protein
Would you expect to see a raised reticulocyte count in acute bleeding?
Yes
What would you expect reticulocyte count to be in ACD?
Low - suppressed
What patients are likely to have secondary polycythaemia and how should they be treated?
Cyanotic heart disease
Cor pulmonale
COPD
Treat with venesection
What pathway does APPT measure?
Intrinsic
What pathway does PT measure?
Extrinsic
How can you measure fibrinogen?
Thrombin clotting time
What does INR measure?
PT - extrinsic pathway
What can cause prolonged PT?
Vit K deficiency
Warfarin anticoagulation
Factor deficiency
What can cause prolonged APPT?
Factor deficiency UF heparin (NOT LMWH) An inhibitor
What are causes of low platelets?
Medication - HIT (heparin induced thrombocytopenia) Alcohol DIC/HUS/TTP ITP Hepatosplenomegaly
What should you do if blood results show low platelets?
Repeat
Full clotting screen - check for DIC
Blood film
What blood results are characteristic of DIC?
Low platelet Prolonged PT and APPT Low fibrinogen High D-dimers Schistocytes on film
Which patient should have a coagulation screen before surgery?
Only if past history of bleeding or family history of bleeding disorder, or in emergency with patient on anticoagulants
What does a low INR mean?
Blood clots more quickly (thicker)
What might you see in FBC a patient with any inflammation e.g. RA?
‘Reactive’
Thrombocytosis
Neutropenia
If a patients INR is too low before surgery, what should you do?
Stop warfarin
Vitamin K - IV takes a few hours to work, PO takes 24 hours.
What are signs and symptoms of thrombocytopenia?
petechieae, epistaxis, purpura
If the lab reports platelet clumping in a sample, what can you do?
Send a citrate sample
What lab test can you do to assess the level to DOAC activity?
anti-Xa activity
What is the mechanism of LMWH?
Inhibits factor Xa (common to both extrinsic and intrinsic)
What are the pharmacokinetics of LMWH?
Longer half life than UFH
Predictable response so no monitoring
Why is a patients creatinine level important if they are taking LMWH?
LMWH accumulates in renal failure
What coagulation test is used to monitor unfractionated heparin?
APPT
What is the MOA of unfractionated heparin?
Binds to anti-thrombin, increasing its ability to inhibit thrombin and factor Xa.
What are side effects of both types of heparin?
Bleeding
HIT (thrombocytopenia) - less common in LMWH
What must you warn patients about when starting heparin?
Do not eat too much Vit K (leafy greens)
Must not become pregnant
Avoid grapefruit juice
Seek advice if bleeding
What is the MOA of warfarin?
Inhibits reductase enzyme that activates vitamin K
What is the antidote for unfractionated heparin?
Protamine sulfate
Which DOAC has an antidote?
Dabigatran - monoclonal antibody antidote
What is the MOA of apixaban and rivoroxaban?
Factor Xa inhibtiors
What is the MOA of dabigatran?
Inhibits thrombin
What can you give a patients INR is > 5 and there is a minor bleed?
IV Vitamin K
What can you do to reverse warfarin in a major bleed?
Give prothrombin complex
