week 10 transfusion medicine Flashcards
What are the different blood components?
RBC
platelets
Plasma
What is leucodepletion?
Whole blood is filtered before further processing to remove white cells
What are the 3 procedures can occur to the plasma after blood components?
Fresh frozen plasma
cryoprecipitate
Fractionation
What is the plasma fractionated to?
Factor concentrates (FVIII, FIX, prothrombin complex)
Albumin
immunoglobulin
How is RBC stored?
Stored at 4oC for up to 35 days from collection.
What is the name of red cells when the plasma is removed?
concentrated red cells
What replaces plasma cells in concentrated red cells?
Replaced by a solution of electrolytes, glycose and adenine to keep the red cells healthy during storage
What is the trasfusion policy of red blood cell transfusion
Usual transfusion time: 1.30 -3hrs
4 hr limit from removal from cold storage to end of transfusion
Use blood warmer for rapid transfusion
Why do we transfuse patients?
To normalize the Hb in anaemic patients
To prevent symptoms of anaemia
To improve quality of life of anaemic patients
To prevent ischemic damage of end organs in anaemic patients.
Does transfusion stop anemia?
No it is just used to improve the quality of life by removing symptoms
What is the mains ymptom of anaemia?
Tissue hypoxia
What is Transfusion threshold (trigger)?
is the lowest concentration of Hb that is not associated with symptoms of anaemia.
What are the mechanisms of adaption to anaemia?
Increased cardiac output Increased cardiac artery blood flow Increased oxygen extraction Increase of red blood cell 2,3 DPG (diphosphoglycerate) Increase production of EPO Increase erythropoiesis
Does transfusion threshold differ betwen subgroups?
Transfusion thresholds differ in various subgroups of patients depending on the balance between mechanisms of adaptation to anaemia and O2 requirements.
What is the affect on respiration in acute anaemia?
In acute anaemia the respiration rate is more markedly increased than in chronic anaemia
Why is oxgen extraction increased in chronic anaemia?
In chronic anaemia the O2 extraction is increased due to the rise of the levels of 2,3 DPG.
What is the response of kidney to chronic anaemia?
In chronic anaemia kidneys respond to hypoxia by increasing the production of erythropoietin and this in turn results in increased erythropoiesis.
What are the parameters that affect the adaptation mechanisms to anaemia?
Acute/chronic anaemia
Underlying conditions
Transfusion of RBC
For a patient with mild symptoms of anaemia how much red blood cell would you transfuse?
Transfusion of ≤70 g/L for patients with mild symptoms of anaemia
For a patient with cardiovascular disease how much red blood cell would you transfuse?
Transfusion of ≤80 g/L for patients with cardiovascular disease
What is anaemia?
Is a condition in which there is a deficiency of red cells or of haemoglobin in the blood, resulting in pallor and weariness.
Origin
What caues of anaemia is treated rather than doing RBC transufsion?
Iron deficiency
B12 and folate deficiency
Erythropoietin treatment for patients with renal disease
How can you correct coagulopathy without the use of transfusion?
Discontinuation of antiplatelet agents
Administration of anti-fibrinolytic agaents
What is cell salvage?
Is a medical procedure involving recovering blood lost during surgery and re-infusing it into the patient.
At what calss of haemorrhage is indication for transfuon neccessary?
Class 3 and definetly at class 4
What is the objectives forPatients on regular transfusions due to myeloid failure syndromes
Symptomatic relief of anaemia
Improvement of Quality of Life
Prevention of ischemic organ damage
What do you have to take into consideration when treating chronic anaemia?
co-morbidities that affect cardiac, respiratory function
iron overload
adaptation to anaemia
What is the aim of Hb for patients who have chronic anaemia?
Threshold Hb 80-100g/dl
What is the objective for a patient on regular transfusions due to inherited anaemia?
suppression of endogenous erythropoiesis to avoid complications due to expansion of the endogenous erythropoiesis
What is the threshold that needs to be aimed at for a patient that has thalassaemia?
Threshold 90-95, target 100-120g/L
What do you take into consideration of thalassaemia?
iron overload
How is platelets stored and what is the transfusion time?
Stored at “room temperature” (22oC)
Shelf-life 5 days from collection
Transfusion time: 30 mins/unit
What is adult therapeutic dose?
Adult therapeutic dose” is platelets from 4 pooled donations
Why transfuse platelets?
Treatment of bleeding due to severe thrombocytopenia (low platelets) or platelet dysfunction
What are you trying to prevent when doing transfuse plateletes?
Prevention of bleeding :
Massive haemorrhage
Bone marrow failure
Prophylaxis for surgery
What are the contraindications of transufe platelets?
Heparin induced thrombocytopenia & thrombosis
thrombotic thrombocytopenic purpura
What is thrombocytopenia?
deficiency of platelets in the blood.
How is fresh frozen plasma stored, the usual dose and trasfusion time?
Stored at –300C for up to 24 months
Thawed immediately before use (takes 20-30 min)
Usual dose 12-15 mL/kg (4-6 units for average adult)
Usual transfusion time: 30 mins/unit
What is the main indication of fresh frozen plasma?
coagulopathy with bleeding/surgery,
massive haemorrhage
thrombotic thrombocytopenic purpura
When do you not transfuse fresh frozen plasma?
Warfarin reversal
Don’t treat bleeding causes by single factor deficiency such as haemophilia
What is the aim of the group and screen testing?
Determination of ABO and Rh(D) group
Patient’s plasma “screened” for antibodies against other clinically significant blood group antigens
If the patient plasma screen is positive what is the next action?
Antibody identification: testing the patient’s plasma against a panel of red cells containing all the clinically significant blood groups, using the Antiglobulin Test
What is the cross matching test?
Patients plasma is mixed with aliquots of donor red cells to see if a reaction (agglutination or haemolysis) occurs
What are the two outcomes of cross matching testing
No reaction
RBC units compatible
No risk of acute haemolysis
Reaction
RBC units incompatible
Risk of acute haemolysis
What are the two groups for the complications of transfusion?
Acute reactions present 24 hours of transfusion
What is the immunological complciations that occurs in acute transfusion reaction?
Acute haemolytic transfusion reaction
ABO incompatibility
Allergic /anaphylactic reaction
TRALI (Transfusion-related acute lung injury)
What is the non immunological complciations that occurs in acute transfusion reaction?
Bacterial contamination
TACO (transfusion associated circulatory overload)
Febrile non-haemolytic transfusion reaction
What is the non immunological complciations that occurs in delayed transfusion reaction?
Transfusion Transmitted Infection (TTI) –viral/prion
What is the immunological complciations that occurs in delayed transfusion?
Transfusion-associated graft-versus-host disease (TA-GvHD)
Post transfusion purpura
What is purpa?
A rash of purple spots on the skin caused by internal bleeding from small blood vessels.
What is the outcome of Acute haemolytic reaction-ABO incompatibility?
Release of free Hb due to:
Deposition of Hb in the distal renal tubule results in acute renal failure.
Stimulation of coagulation results in microvascular thrombosis
Stimulation of cytokine storm
Scavenges NO resulting in generalized vasoconstriction
What is the onsent of Acute haemolytic reaction-ABO incompatibility?
Severe reactions may occur early in the transfusion, within the first 15 min
Milder reactions may occur later but usually before the end of transfusion
What is the signs and symptoms of Acute haemolytic reaction-ABO incompatibility?
Fever and chills Back pain Infusion pain Hypotension /shock Hemoglobinuria (may be the first sign in anesthetized patients) Increased bleeding (DIC) Chest pain Sense of “impending death”
What percentage of Acute haemolytic reaction-ABO incompatibility is fatal?
20-30%
What is the cause of Acute haemolytic reaction -ABO incompatibility ?
Always a human error either due to mistake in patient identification or the correct product use
What is the cause of delayed haemolytic reaction?
Delayed haemolytic reaction is due to immune IgG antibodies against RBC antigens other than ABO
The antibodies are formed after the transfusion
What is the onset time of delayed haemolytic reaction?
Onset 3-14 days following a transfusion of RBC
What is the clinical features of delayed haemolytic reaction?
fatigue,
jaundice,
and/or fever
What is the libaoratory findings of delayed haemolytic reaction?
Drop in Hb
Increased LDH
Increased indirect bilirubin
Direct antiglobulin test is Positive
What is a serious complication of transfusion?
Transfusion related acute lung injury
What is the cause of transfusion related acute lung injury?
Donor has antibodies to recipient’s leucocytes
What is the effect of transfusion related acute lung injury on the lung pathology?
Activated WBC lodge in pulmonary capillaries
Release substances that cause endothelial damage and capillary leak
What type of transfusion is complicated by transfusion related acute lung injury?
Almost always complicates transfusion of plasma rich components
What is the onset of transfusion related acute lung injury?
Sudden onset of “Acute Lung Injury” occurring within 6 hours of a transfusion
What are the clinical signs of transfusion related acute lung injury?
Hypoxemia
New bilateral chest X-ray infiltrates
No evidence of volume overload
What is the treatment for TRALI?
Mild forms of TRALI may respond to supplemental oxygen therapy.
Severe forms may require mechanical ventilation and ICU support.
Is diuretics or corticosteroids used in TRALI?
There is no role for diuretics or corticosteroids
What are the laboratory investigations of TRALI?
Donor is tested for HLA and granulocyte antibodies.
The recipient is tested for expression of neutrophil antigens
How do you confirm the diagnosis of TRALI?
Donor has antibodies against antigens that are expressed on recipient’s granulocytes.
What is the presentation of Transfusion-associated circulatory overload?
Symptoms: sudden dyspnea orthopnoea tachycardia hypertension hypoxemia.
Signs
Raised BP
elevated jugular venous pul
What are the risk factors of TACO?
elderly patients small children Patients with compromised left ventricular function increased volume of transfusion increased rate of transfusion
What is the cause of urticarial Rash?
Hypersensitivity to a ‘random’ plasma protein
What is anaphylaxis?
Severe, life-threatening reaction soon after transfusion started
What is the consequence of anaphylaxis?
Wheeze/ asthma, increase in pulse and decrease in BP (shock)
Laryngeal oedema/ facial oedema
What are the laboratory investigations for anaphylaxis?
Quantification of IgA, testing for anti-IgA antibodies.
