Blood transfusion Flashcards
How are blood components obtained?
centrifugin anticoagulated blood to separate into red cells, buffy coat and plasma
How are blood products obtained?
subjecting human plasma to a manufacturing process to obtain various plasma fractions
What makes blood products more risky than blood components?
blood products are in batches from thousands of donations compared to 1-4 donors so higher risk of infection
How many people make up a pool of platelets?
4 standard blood donation
What is platelets-apheresis?
complete adult dose of platelets from a single donor
What are the anticoagulatns used in transfusion?
citrate-based
What tests are carried out on donated blood?
HIV 1 and 2; HCV; HBV; syphilis; HTVL 1 and 2; HEV
What temperature must red cells be stored at?
4 degrees +/-2
What is the shelf life of red cells?
35 days
How long can red cells be out of the fridge before thye cant be put back in?
30 minutes
Once out of the fridge, how long should red cells be transfused in?
within 4 hours
How are platelets stored?
22 degrees with continual agitation
What is the shelf life of platelets?
7 days if bacterial monitoring system is employed
When should you transfuse after taking platelets out of storage?
within 1 hour
what should FFP be stored at?
-30
What is the shelf life of FFP?
3 years
Why should platelets not be put in a fridge?
cold activates platelets and wontactivate again
What ABO blood group has no ABO antibodies?
AB
What type of antibody are ABO antibodies?
IgM as ABO antigens are constantly changing by small amounts
What chromosome is ABO blood group inherited on?
9
Why do most of us not have antibody against Rh in the blood?
no bacteria carry substance that resembles Rh(D)
What is blood group determination based on?
agglutination phenomenon
What are the commonest irregular red cell antibodies?
anti-D; anti-K; anti-c; anti-E; anti-Fya
What is length of time non-urgent transfusion of one unit of red cell conentrate generally?
2-3 hours
What might bubbles in the blood bag indiacte?
bacterial contamination
What rise of Hb is expected with each unit of red cells transfused?
10g/L
what is the blood volume?
70ml/kg
How long does normal sending for compatible blood take?
an hour
Is cross-matching needed for platelet transufsion?
no
what is the threshold for platelet transfusion?
10x10^9/L
What would cause the threshold for platelet transfusion to go up?
if patient has fever as platelet survival is shorter with infection; or bleeding; or bruising;
What is the commonest indication for FFP?
correct coag deficiency in patient with liver disease who are bleeding
What are the indications for FFP?
bleeding or surgery in liver disease with impaired coag; coagulopathy following transfusion; DIC
What happpens in immediate haemolytic transfusion reaction?
anti-ABO antibodies to wrong blood group transfusion bing and activate complemetn and rupture of the memrbane; this releases thromboplastins causing more complement and DIC; complement vasodilates
What 3 systems are activated with an acute haemolytic tranfusion reaction?
kinin; complement and coagulation systems
What are the net effects in acute haemolytic transfusion reaction
systemic hypotension; DIC; renal vasconstriction; renal intravascular thrombi; shock and renal failure
What blood samples should be obtained with immediate haemolytic transfusion reaction?
blood to transfusion lab; blood cultures; FBC; coag screen; biochemistry; haptoglobin level
What is the function of haptoglobin?
binds free Hb
What are the features of an acute haemolytic reaction?
pyrexia/rigors; dizziness; tachy; hypotensive; pallor/sweating; HA/chest/lumbar pain; local pain at infusion; cyanosis
What antibodies are usually implicated in delayed haemolytic transfusion reactions?
irregular antibodies
What are the lab features of delayed haemolytic reactions?
anaemia; spherocytic red cells on blood film; elevated bilirubin and LDH; positive DAGT and/or red cell allo-antibody; renal failure
What is the management of an immediate haemolytic transfusion reaction?
stop transfusion; start IV fluids; obtain blood samples
What blood samples should be collected after an immediate haemolytic transfusion reaction?
transfusion lab; FBC and blood flim; coag screen; biochemistry; blood cultures and serum haptoglobin
What are the features of a dleyaed haemolytic transfusion reaction?
symptoms similar but less acute than IHTR; unexplained fall in Hb; appearance of jaundice; renal failure of biochemical features; detection of positive DAGT or irregular antibodies in post-transfusion blood samples
Why is complement not activated in delyaed haemolytic reactions?
most irregular antibodies do not activate complement
Why is the lack of complement in delayed haemolytic reactions significant?
no intravascular red cell destruction but extravascular eg spleen
why are there spherocytes with delayed haemolytic reaction?
when antibody coated RBCs go through spleen are destroyed by macrophages, but some excape back to circulation with damaged cell membrane–shape changes
What is a postiive direct antiglobulin test?
addition of anti-human globulin to sensitised red cells to look for agglutination
What causes febrile non-haemolytic transfusion reactions?
recipient has anti-HLA antibodies that bind to residual white cells within the component being transfused or vasoactive and pyrogenic substances being released from WBCs during storage
What are the features of febrile non-haemolytic transfusion reaction?
rapid temperature rise 1-2 degrees; chills; rigors
What is the prevention of febrile non-haemolytic transfusion reactions?
anti-pyretics and leucodepleted blood components
What is an urticarial reaction to blood products?
mast cell IgE response to infused plasma proteins resulting in rash/weals within few minutes of starting transfusion
What is the management of urticarial reaction to trasnfusion?
slow transfusion and consider anti-histamines
What is the management of severe urticarial reactions?
need to wash blood components of all residual plasma and suspend cells in plasma
What are the symptoms of bacterial infection of transfusion?
fever; immediate collapse; shock ; DIC
What bacteria are associated with red cells?
pseudomonas; yersinia
What bacteria are associated with platelets?
staph, strep, serratia, salmonellae
What is the chance of blood components infecting a patietn with hIv?
1 in 6 million chance
