Blood Products Flashcards
What are the different blood fractions?
1) Packed red cells
2) Platelet rich plasma
3) Platelet concentrate
4) Fresh frozen plasma (FFP)
5) Cryoprecipitate
6) SAG-Mannitol blood
What is a blood product?
A blood product is any part of the blood that is collected from a donor for use in a blood transfusion.
What are the two important blood groups?
1) ABO blood system
2) group D of the rhesus system
How can a patient’s blood group be classified according to the Rhesus system?
RhD+ or Rh-
This refers the presence or absence of Rhesus D surface antigens on the RBCs.
I.e. RhD+ means they have RhD antigens present.
Is being RhD+ or RhD- more common?
RhD+ (85%) is more common.
How can RhD be implicated in pregnancy?
1) A woman is born with RhD- blood. Her partner is RhD+ and she becomes pregnant with a fetus that is also RhD+.
2) During childbirth, she comes into contact with the foetal (Rh+ve) blood and develops antibodies to it.
3) She later becomes pregnant with a second child that is also Rh +ve.
4) The woman’s anti-D antibodies cross the placenta during this pregnancy and enter the foetal circulation, which contains RhD+ blood, and bind to the foetus’ RhD antigens on its RBC surface membranes.
5) This causes the foetal immune system to attack and destroy its own RBCs, leading to foetal anaemia –> haemolytic disease of the newborn (HDN).
What happens when a RhD- person is given RhD+ blood?
A RhD- patient will make RhD antibody (anti-D) if they are given RhD+ blood.
This is not a problem as they cannot then go on to attack their own RBCs as they do not have RhD present on their RBC membrane.
How can haemolytic disease of the newborn be avoided?
If the mother is RhD negative, she’ll be offered injections of anti-D immunoglobulin at certain points in her pregnancy when she may be exposed to the baby’s red blood cells.
What does the ABO blood group refer to?
The presence of A and / or B antigens on the surface of RBCs.
I.e. RBCs with A antigens will produce anti-B antibodies.
For blood type A, give the:
1) antibodies in plasma
2) antigens on RBC
3) blood types compatible in emergency
1) anti-B
2) A antigen
3) A, O
For blood type B, give the:
1) antibodies in plasma
2) antigens on RBC
3) blood types compatible in emergency
1) anti-A
2) B antigen
3) B, O
For blood type O, give the:
1) antibodies in plasma
2) antigens on RBC
3) blood types compatible in emergency
1) anti-A and anti-B
2) none
3) O
For blood type AB, give the:
1) antibodies in plasma
2) antigens on RBC
3) blood types compatible in emergency
1) none
2) A and B antigens
3) A, B, AB, O
Which blood type is the universal donor?
O negative: this blood can be given to anybody, irrespective of the recipient’s blood group, because there are no AB or Rhesus antigens on the donor RBC surface membrane.
Which blood type is the universal recipient?
AB+ve: you can give this recipient any donor blood, irrespective of the ABO or Rhesus status.
What 2 blood tests are performed prior to blood transfusion?
1) Group and save (G&S)
2) Crossmatch (X-match)
What does G&S involve?
This determines the patient’s blood group (ABO and RhD) and screens the blood for any atypical antibodies.
The process takes around 40 minutes.
No blood is issued.
When is a G&S recommended?
If blood loss is not anticipated, but blood may be required should there be greater blood loss than expected.
What is a X-match involve?
Involves physically mixing the patient’s blood with the donor’s blood, in order to see if any immune reaction takes places.
If it does not, the donor blood is issued and can be transfused in to the patient.
This process also takes ~40 minutes, in addition to the 40 minutes required to G&S the blood (which must be done first).
What must be done first, XM or G&S?
G&S
When is a XM done?
A X-match is done if blood loss is anticipated, but the surgeon will usually inform you of this.
What stages are involved in requesting blood products?
1) Using 3 points of patient identification e.g. name, DOB, and patient number.
2) Consent the patient appropriately.
3) Labeling the bottle at the bedside.
4) Completing the transfusion request form at the bedside.
What is cytomegalovirus (CMV)?
A common congenital infection that may lead to sensorineural deafness and cerebral palsy.
When is it especially important that CMV negative blood is given?
CMV negative blood should be given to:
a) women during pregnancy
b) intra-uterine transfusions
c) neonates (up to 28 days)
What is irridiated blood?
Irradiated blood is blood that has been treated with radiation (by x-rays or other forms of radioactivity) to prevent Transfusion- Associated Graft-versus-Host Disease (TA-GvHD).
What disease do irradiated blood products reduce the risk of?
graft-versus-host-disease in at risk populations
Which populations should receive irradiated blood?
1) Those receiving blood from first or second-degree family members
2) Patients with Hodgkin’s Lymphoma
3) Recent haematpoietic stem cell(HSC) transplants
4) After Anti-Thymocyte Globulin (ATG) or Alemtuzumab therapy
5) Those receiving purine analogues (e.g. fludarabine) as chemotherapy
6) Intra-uterine transfusions
How should blood products be prescribed if a patient requires more than one unit of blood?
Each unit must be prescribed individually
Whilst the patient is receiving the blood transfusion, how often should observations be carried out?
1) before transfusion starts
2) 15-20 minutes after it has started
3) at 1 hour
4) at completion
What is the major constituent in packed red cells?
RBCs
What cannula should be used to administer blood products?
Why?
Blood products should only be administered through a green (18G) or grey (16G) cannula.
Otherwise the cells haemolyse due to sheering forces in the narrow tube.
Indications for transfusion of packed red cells?
1) acute blood loss
2) chronic anaemia where the Hb ≤70g/L (or ≤100g/L in those with cardiovascular disease)
3) symptomatic anaemia
Over what period should packed red cells be administered?
2-4 hours
How soon after coming out of the store should packed red cells be administered?
Within 4 hours of coming out of the store.
1 unit of blood should increase a patient’s haemoglobin by how much?
Approx 10g/L
How are packed red cells obtained?
Obtained by centrifugation of whole blood.
What is the major constituent of fresh frozen plasma (FFP)?
Clotting factors (also albumin & immunoglobulin)
Give some indications for FFP
1) Disseminated Intravascular Coagulation (DIC)
2) Any haemorrhage secondary to liver disease
3) All massive haemorrhages (commonly given after the 2nd unit of packed red cells)
Over what time period is FFP typically administered?
30 mins
What are the major constituents in cryoprecipitate?
- fibrinogen
- von Willebrands Factor (vWF)
- factor VIII
- fibronectin
Indications for cryoprecipitate?
1) DIC with fibrinogen <1g/L
2) von Willebrands Disease
3) Massive haemorrhage
What does Factor 5 Leiden involve?
This is an inherited disorder of blood clotting that involves a mutation in Factor 5.
This increases the risk of clotting (as it resists degradation by protein C).
What happens in von Willebrand disease?
vWf is deficient, predisposing to bleeding.