T7-L2: Blood Transfusion

Question 1

What are the indications for transfusion of red blood cells?

Answer 1

In a RBC transfusion most of the plasma is removed to leave concentrated RBC. It has a haematocrit of 60%. 1 unit of packed RBC raises Hb by 10g/L.

It is used in:

• Bleeding
• Anaemia with severe symptoms until symptoms resolve
• Acute anaemia with mild symptoms
• Chronic anaemia

Question 2

What are alternatives to transfusions for treatable causes of anaemia?

Answer 2

Treatment, through replacement, or iron, B12 and folate or erythropoietin in those with renal disease.

Question 3

What are the two methods of platelet transfusion?

Answer 3

• Pooled platelets - 1 unit of platelet is produced from a unit of a whole blood - 4-6 of these used from different donors are pooled together in a single pack
• Apheresis - this collects platelets and returns all other blood constituents to the donor.

Question 4

What are the indications for transfusion of platelets?

Answer 4

Treatment of Bleeding:

• Massive haemorrhage/major bleed to maintain platelet count
• Critical site bleeding to maintain platelet count
• Any other clinically significant bleeding

Prevention of bleeding:

• Bone marrow failure
• Pre-surgery

Question 5

What is FFP?

Answer 5

Fresh Frozen Plasma. Contains all clotting factor at physiological levels.

A therapeutic dose is 12-15 mL/kg (4 units). It is stored at -30 degrees Celsius for up to 36 months. Usual transfusion time is 30 minutes/unit.

Question 6

What are contraindications of transfusion of FFP?

Answer 6

Not used to:

• Treat a single factor deficiencies where a factor concentrate is available such as Hameophillia A
• To correct abnormal clotting results in patents that are not bleeding/having procedures
• To reverse warfarin

It is instead used to replace clotting factors in patients with multiple factor deficients (acquired coagulopathies). This may be to treat bleeding in patients with significantly abnormal clotting results to to correct clotting results prior to surgery.

Question 7

What do we use to reverse Warfarin?

Answer 7

Warfarin inhibits clotting factors II, VII, IX and X. Prothrombin complex concentrate contain these factors. A high concentration of these factors can help to revere the effects better than FFP would. Also Vitamin K.

Question 8

What are the indications for transfusion of Cryoprecipitate?

Answer 8

Cryoprecipate is extracted from FFP duding the thawing process. It contains fibrinogen, vWF, Fc VIII and Fc XIII. It is mainly used for fibrinogen content.

It is used to as a concentrated source of fibrinogen in acquired coagulopathies such as massive haemorrhage, DIC, liver failure etc. It is not used to correct low fibrinogen in patents that are not bleeding or having procedures.

Question 9

List non-immunological risks of transfusion.

Answer 9

• Transfusion Transmitted Infections
• Transfusion Associated Circulator Overload
• Febrile Non-Haemolytic Transfusion Reaction
• Iron Overload

Question 10

List immunological risks of transfusion.

Answer 10

• Acute haemolytic transfusion reaction due to incompatibility
• Delayed haemolytic reaction
• Post transfusion purpura
• Allergic /anaphylactic reaction
• TRALI (Transfusion-related acute lung injury)
• TA-GvHD (Transfusion-associated graft-versus-host disease )

Question 11

What is Transfusion Transmitted Infection? How do we prevent this?

Answer 11

• Risk of infection such as HIV, Hep B and Hep C - these were transferred in blood products (particularly fractionated blood products) infected many in 1970-1980. Every blood donation is tested now for these infections and more.
  - Can also get delayed reactions - over 24 hours after transfusion

Question 12

What are Febrile Non-haemolytic Transfusion reactions?

Answer 12

Non-hemolytic febrile transfusion reactions are usually caused by cytokines from leukocytes in transfused red cell or platelet components, causing fever, chills, or rigors. In the transfusion setting, a fever is defined as a temperature elevation of 1º C or 2º F.

        - This occurs more commonly with RBC 
	- Unpleasant but not life-threatening 
	- It leads to a slight increase in blood temp, may have rigors and tachycardia 
	- Treat with paracetamol and slow the transfuse - if an increase in temperature by more than 2 degrees we can discharge the unit

Question 13

What is Transfusion associated Circulatory Overload (TACO)?

Answer 13

Transfusion-associated circulatory overload (TACO) is a common transfusion reaction in which pulmonary edema develops primarily due to volume excess or circulatory overload.

		- More common with FFP as you can give 2L of fluid 
		- Occurs during or up to 6 hours after perfusion 
		- Risk factors are elderly patients, small children, LVF, renal impairment 
		- We prevent this by identifying people at risk to make sure we are given an appropriate volume at an appropriate rate 
		- We may need to give furosemide after 
		- If they develop TACO, the treatment is supportive
		- Treatment is similar to the treatment heart failure

Question 14

What is the most common acute haemolytic reaction in transfusions?

Answer 14

ABO Incompatibility - This is fatal in 20-30% of patients.

Question 15

What is the effect of haemolysis on the body?

Answer 15

• Fever, Rigors and hypotension due to cytokine shower
• Bleeding from DIC
• Acute Kidney injury as haemoglobin is toxic to the kidneys
• Vasoconstriction, Hypertension and Angina
• Nitric oxide depletionPre transfusion testing on patients is used to determine ABO and Rh(D) group.

Question 16

What is ‘Group and Save’?

Answer 16

A group and save is required whenever there is possibility of a patient requiring transfusion e.g. surgical risk, haemorrhage and anaemia.

A group and save is the sample processing. It consists of a blood group and an antibody screen to determine the patients group and whether or not they have atypical red cell antibodies in their blood.

They will then look in the plasma of the patient for any other antibodies we would not expect to find. Most of the time they will be negative to further testing. If they have had a transfusion before or pregnancy, they will have antibodies against another blood group antigen e.g. other blood group antigens (other than ABO). More tests are done to find out what antibody is present.

Question 17

What is crossmatching in compatibility testing?

Answer 17

The plasma of the patient with the donor red cells to see if there is a reaction (agglutination occurs). A reaction means that RBC units are incompatible. There is a risk of acute haemolysis. It is an in vitro transfusion in the lab to done to double check.

Question 18

What is a delayed haemolytic reaction?

Answer 18

This is due to post transfusion formation of antibodies against RBC antigens other than ABO.

	The onset is 3-14 days following a transfusion of RBC. 

This is seen as a drop in Hb, increased LDH, increased unconjugated bilirubin. The RBC may be destroyed. They may have fatigue, jaundice or fever or just asymptomatic but low Hb.

Question 19

What are the features of allergic reactions to transfusion?

Answer 19

The patient is hypersensitive to something in the plasma. Can be reaction to random proteins.

It is usually when they are having a product with lots of plasma such as FFP and platelets.

Clinical features:

- Rash, urticaria, pruritus, wheeze 
- ± rigors and fever
- Periorbital oedema

Treatment- Antihistamines, steroids, slow rate/discontinue transfusion

In anaphylaxis it will come on very abruptly. Management is via ABCDE - adrenaline, fluids etc. It is more common in patients with a IgA deficiency and anti-IgA antibodies.

Signs and symptoms

- Laryngeal oedema
- Bronchospasm
- hypotension
- Swelling

Treatment ABCDE, IM adrenaline, antihistamine IV, steroid IV, fluid

Question 20

What is Transfusion Related Acute Lung Injury (TRALI)?

Answer 20

Transfusion-related acute lung injury (TRALI) is a rare but serious syndrome characterized by sudden acute respiratory distress following transfusion. It is defined as new, acute lung injury (ALI) during or within six hours after blood product administration in the absence of temporaly-associated risk factors for TRALI.