Blood Transfusion Flashcards
Indications for blood transfusion
-RBC
=To replace blood lost during or after surgery/ to treat anaemia
=Not enough RBC to carry oxygen, if larger amounts of blood than 2-3 units, replace so not too anaemic
-Platelets
=To increase the number of platelets in your blood to replace the platelets which are not working properly
=Prevent bruising, help clot. Bone marrow not working/ using up platelets faster than produced
-Plasma
=Reverse low levels of clotting factors (where clotting factor concentrates unavailable)/ treatment of rare blood disorders
=Clotting factors to clot, Fresh frozen plasma, cryoprecipitate (fibrinogen)
Risks of transfusion
-Incompatible ABO/D blood group
-Transmission of HBV/ HIV
-Transmission of variant Creutzfeldt-Jakob Disease
-Allergic reactions
Alternatives to blood transfusion
-Autologous transfusion: use own blood
-Allogenic: iron erythropoietin, tranexamic acid
What does a blood transfusion involve?
-Pre-transfusion sample required
-Red blood cells transfused over 1.5-2 hours, or up to 3 hours if at risk of transfusion associated circulatory overload (TACO)
-Emergency situation: platelet or plasma transfusion around 30 mins
Consent in blood transfusions
-Consent issues do not delay life-saving treatment
=Clinicians must act in the best interests of the patient unless there is clear evidence of an advanced directive in patient notes
=In emergency, retrospective patient information must be provided prior to discharge
-Written documentation not absolutely necessary
ABO Serology
-The ABO groups are named after the antigens present on the red cell surface
-In the ABO groups, individuals produce antibodies (immunoglobulins) against the antigens that are not present on their own red cells. Thus, group O individuals have, in their plasma, antibodies to both group A and group B while group AB individuals do not have either of these antibodies
What are compatible RBC vs incompatible?
Red cells are compatible if there are no ANTIGENS on their surface that will react with the ANTIBODIES in the patient’s plasma
-Blood components that contain plasma are compatible if there are no ANTIBODIES in the donor plasma that will react with the ANTIGENS on the patient’s red cells.
=In most instances platelets, fresh frozen plasma and cryoprecipitate are issued on the basis of the patient’s ABO and D blood group alone, they are not crossmatched against the patient, as they do not have a large number of RBC antigens present in the component.
An ABO incompatible transfusion is classed as a ‘never event’ by the Department of Health (2018)
=The transfusion of only a few mLs of the wrong (incompatible) ABO group can trigger a massive immune response leading to shock and disseminated intravascular coagulation. Individuals may die from circulatory collapse, severe bleeding or renal failure, often within minutes or hours.
Describe D blood
-In the UK approximately 85% of the population are D positive and 15% are D negative:
=Red cells which carry the D antigen are D Positive
=D Positive patients can receive any D type blood
=D Negative patients where possible should receive D Negative blood, on occasion it may be necessary to give D Positive blood e.g. adult male patient
=D Negative patients can make anti-D antibodies if they are exposed to D Positive cells through transfusion or pregnancy.
-D negative patients of childbearing potential SHOULD NOT be transfused with D positive red cells.
Pre-transfusion testing
-Check that the patient identification details on the sample and request form are fully complete and match
-Check the historical records
-Group: Identify ABO and D group
-Screen: Check plasma for antibodies
-Crossmatch: Select component
-The patient’s serum or plasma can be saved for up to 7 days in case later crossmatch is required but only if the patient has not been pregnant or transfused within the last 3 months. In this case serum is only held for 72 hours (3 days).
-After any transfusion or pregnancy when the patient is exposed to foreign antigens, there is a risk that the patient will develop antibodies to other antigens on the red cell surface.
When to order blood
It is important that blood is only crossmatched for a patient who is likely to require transfusion. Nowadays most blood requested is for Medical patients. Surgical patient requests need to follow the Maximum Surgical Blood Ordering Schedule (MSBOS), which is a locally agreed tariff, that indicates how many units should be ordered for specified surgical procedures.
For example, patients having a surgical procedure who are unlikely to require blood and who have a negative antibody screen, can have blood provided rapidly if required.
If the patient has a positive antibody screen further work may need to be carried out by the HTL (e.g. serological crossmatch) before components can be issued.
Blood availability
-Group O (“emergency or flying squad blood”) - immediate - 5 minutes, inform Hospital Transfusion Lab
-Group Compatible (i.e. same group as patient) - 10-15 minutes.
-Fully screened and crossmatched - approximately 30 - 40 minutes upon receipt of sample (may be hours/days if an antibody is found).
Preparation of blood components
-Donors can generally donate approximately 470mLs of whole blood up to three times a year
-Donation= platelet pheresis= filter to remove leucocytes= patients
What is a bag of red blood cells?
-Red cells in “additive solution” contain up to 20 mLs of plasma
-They are leucocyte-depleted
-Packed volume varies - 220->355 mLs
-Haematocrit (HCT) varies but is typically 0.55
-Stored for up to five weeks at 4oC +/- 2oC
-Can be irradiated and / or CMV negative (specific requirements).
-All red blood cell components should be administered within 4 hours of removal from cold storage. Standard red blood cells have a shelf life of 35 days from the time of donation.
-Red cell units irradiated within 14 days of collection expire 28 days after collection
Indications for red cells
Blood components are still being authorised inappropriately for reasons not supported by evidence or accepted clinical guidelines (SHOT).
The reason for transfusing red cells is to improve oxygenation to the tissues by increasing the circulating red cell mass.
-The main indications include:
=Bleeding
=Anaemia
=Haemoglobin disorders.
=Acute blood loss exceeds 30-40% of blood volume
=If the Hb is below 70g/L in an otherwise fit patient (aim to keep Hb above 70g/L)
=If the Hb is between 80-90 g/L in a patient with cardiovascular disease (aim to keep Hb between 80-100g/L).
-These criteria can also be applied to critically ill patients without acute bleeding. In all cases the clinical context must be considered and not just the patient’s Hb level.
What’s in a bag of platelets
-Apheresis - single donor
-Pooled - whole blood derived (4 donations)
-One pack (apheresis or pooled) is termed one Adult Therapeutic Dose (ATD)
-One ATD should increase the platelet count by at least 20 x 109/L
-Stored for up to 7 days at room temperature (22°C), on an agitator. All blood services in the UK screen for bacterial contamination routinely.
Indications for platelets
Most platelets are given to prevent rather than to treat bleeding when the platelet count is less than or equal to 10 x 109 or between 10 and 20 x 109/L if there are additional risk factors for bleeding.
Absolute thrombocytopenia, in the absence of any abnormality, is unlikely to be complicated by serious spontaneous haemorrhage if the count remains above 5 x 109/L. Platelets are given to prevent bleeding (prophylactic) in the following clinical situations:
=Reversible bone marrow failure including allogeneic stem cell transplant and critical illness.
=Chronic bone marrow failure if patient is receiving intensive treatment or to prevent persistent bleeding.
Prophylactic platelet transfusions may not be required if patient is well and is having an autologous stem cell transplant.
Prophylactic platelet transfusions are not required if patient has chronic bone marrow failure and is stable and well.
Platelet transfusions are also given to prevent bleeding prior to an invasive procedure. Platelet transfusions are given to treat bleeding. However, in some conditions platelets can be contra-indicated.
Thresholds for prophylactic platelet transfusion
The expected platelet increment should be at least 20x109/L. If the increase is persistently below 20x109/L this may suggest refractoriness.
What are plasma components?
Plasma components (FFP, Cryo) are transfused to replace coagulation factors in the treatment of bleeding and for plasma exchange. They can cause acute transfusion reactions (moderate and severe allergic and life-threatening anaphylaxis) and pulmonary complications, including transfusion associated circulatory overload (TACO).
TACO is now the most frequent cause of death and major morbidity associated with transfusion (SHOT reports since 2008). Even small volumes of plasma components can cause TACO, especially in patients with pre-existing cardiac disease or circulatory failure, pulmonary oedema, COPD or low body weight.
Describe FFP
FFP is leucodepleted and prepared from anti-coagulated, whole blood or collected by apheresis and rapidly frozen to maintain activity of labile coagulation factors. Solvent detergent treated FFP (e.g. Octaplas LG ®) is available and may be indicated in specific conditions. Imported plasma is no longer indicated for those born on or after the 1st January 1996. (SaBTO, 2019)
FFP Facts:
=Pack volume varies: 200 - 300 ml
=It is stored at -25°C or below for up to 36 months (3 years)
=Once thawed it can be stored in a temperature-controlled blood fridge before transfusion, provided the infusion is completed within 24 hours of thawing.
=In some circumstances, pre-thawed standard FFP can be held in a temperature-controlled blood fridge for up to 120 hours; e.g. for trauma patients with major blood loss.
=Group O FFP should only be given to Group O patients.
=FFP from a donor of an identical ABO Group should be used as the first choice
Who can use FFP?
In an emergency when a patient’s blood group is unknown, non-identical FFP from group A or B or AB donors can be given, provided it is ‘high-titre negative’ for anti-A or anti-B.
D positive or D negative FFP is suitable, regardless of a patient’s D status. Anti-D prophylaxis is not required if FFP from a D positive donor is given to a D negative recipient.
Contact your Blood Transfusion Laboratory if you have a query about FFP compatibility for a particular patient.
Indications for FFP
-Inherited coagulation factor deficiency where no suitable factor concentrate is available, e.g. Factor V deficiency
-Acute disseminated intravascular coagulation (with evidence of bleeding)
-Thrombotic thrombocytopenic purpura (TTP) - BSH guidelines recommend the use of solvent detergent FFP (SD-FFP)
-Major haemorrhage
-Prophylaxis before surgery (or another invasive procedure) if abnormal coagulation test results AND one or more additional risk factors for bleeding:
=Personal or family history of abnormal bleeding
=Procedure associated with major blood loss
=Procedure involves critical tissues such as eye, brain or spinal cord
=Concurrent thrombocytopenia
When should FFP not be administered
-As a plasma expander to correct hypovolaemia.
-For the reversal of warfarin anticoagulation, treatment of bleeding in this circumstance is vitamin K, with or without prothrombin complex concentrate.
-To non-bleeding patients with liver disease
-To critically ill patients with prolonged PT or APPT in the absence of bleeding.
-For patients with liver disease: there is no evidence that prophylactic FFP reduces the risk of bleeding from percutaneous liver biopsy or variceal haemorrhage.
Dose of FFP
-Prophylaxis before a surgical or invasive procedure - suggested dose of FFP is 15 ml/kg body weight (although not evidence based) in a non-bleeding patient with abnormal coagulation test results AND one or more additional risk factors for bleeding
-Typical paediatric dose: 15-20mL/kg.
-Treatment of major haemorrhage - initial recommended dose is 15-20 mL/kg body weight.
What is Cryoprecipitate?
Cryoprecipitate (Cryo) is produced by slowly thawing fresh frozen plasma at 4-6°C, followed by resuspension of factors FVIII, von Willebrand factor, FXIII, fibronectin and fibrinogen in 20-60 ml plasma.
Essential facts:
=Single donor units are pooled into 5-donor packs, with volume 200-280 ml
=Storage -25°C or below for up to 36 months
=Once thawed, cryoprecipitate should ideally be transfused immediately or kept at room temperature and transfused within 4 hours.
=The ABO group of cryoprecipitate should preferably be identical with that of the recipient.
There is wide variation in FVIII and fibrinogen levels between packs
