Blood Transfusion (Haematology Pathology)

Question 1

What are the main components of blood?

Answer 1

Red blood cells
White blood cells
Platelets
Plasma

Question 2

What is the usual transfusion time for 1 unit of RBC?

Answer 2

1.30 - 3 hrs

Question 3

Why do we transfuse patients?

Answer 3

To prevent ischaemic damage of end organs in anaemic patients.

Transfusion with RBC in anaemia helps to restore the oxygen carrying capacity.

Question 4

What is the main symptom of anaemia?

Answer 4

Hypoxia

Question 5

What is the transfusion threshold (trigger)?

Answer 5

Transfusion threshold (trigger) is the lowest concentration of Hb that is not associated with symptoms of anaemia

Question 6

What are the mechanisms of adaption to anaemia?

Answer 6

1) increased cardiac output
2) Increased cardiac artery blood flow
3) Increased oxygen extraction
4) Increase of red blood cell 2,3 DPG (diphosphoglycerate)
5) Increase production of Erythropoeitin
6) Increase erythropoiesis

Question 7

What are 3 treatable causes of anaemia?

Answer 7

1) Iron deficiency
2) B12 and folate deficiency
3) Erythropoietin (renal patients)

Question 8

What % reduction of blood volume indicates a “probably necessary” transfusion? (also what class of haemorrhage is this?)

Answer 8

Class 3 haemorrhage.

30-40% blood loss

Question 9

Why would a patient have regular transfusions due to myeloid failure syndromes?

Answer 9

1) Symptomatic Relief of anaemia
2) Improve Qual of life
3) Prevent ischaemic organ damage

Question 10

Why would we give regular tranfusions to a patient with inherited anaemias such as thalassaemia?

Answer 10

to suppress endogenous erythropoiesis

Question 11

What is thalassaemia?

Answer 11

Thalassemia is an inherited blood disorder in which the body makes an abnormal form of haemoglobin. results in excessive destruction of red blood cells, which leads to anemia.

Question 12

What is the usual tranfusion time for platelets?

Answer 12

30 mins / unit

Question 13

Why do we transfuse platelets?

Answer 13

1) Treatment of bleeding due to severe thrombocytopenia (low platelets) or platelet dysfunction.
2) PREVENTION of bleeding

(haemorrhage, bone marrow failure, prophylaxis for surgery)

Question 14

Why do we tranfuse fresh frozen plasma?

Answer 14

1) massive haemorrhage
2) thrombotic thrombocytopenic purpura (excessive coagulation of blood)
3) impaired clotting with bleeding / surgery

Question 15

what are the tests done prior to a transfusion?

Answer 15

-determine blood group / Rh(D) by crossmatch / compatibility testing

Question 16

What are the acute complications/adverse effects of blood transfusal

acute =

Answer 16

Immunological:

• acute haemolytic transfusion reaction due to ABO incompatibility.
• Allergic / anaphylactic reaction

Non-immunological:

• Bacterial contamination
• TACO (transfusion associated circulatory overload)

Question 17

What are the delayed complications of transfusion?

chronic = >24hours of transfusion

Answer 17

Immunological:
-post transfusion purpura (rash)

Non Immunological:
-Transfusion transmitted infection (viral / prion)

Question 18

What infection has the highest risk of transmission during transfusion?

Answer 18

Hep B (1.5 in 1 million)

• 2nd is HIV (1 in 6 million)
• 3rd is Hep C (1 in 30 million)

Question 19

What is the pathology of an acute haemolytic ABO incompatibility reaction?

Answer 19

1) Release of free Hb
2) Deposition of Hb in the distal renal tubule causes acute renal failure.
3) coagulation causes microvascular thrombosis
4) cytokines released
5) vascoconstriction

Question 20

What are the signs and symptoms of an acute haemolytic ABO incompatibility reaction?

Answer 20

1) fever / chills
2) Back pain
3) hypotension / shock
4) Increased bleeding
5) chest pain

Question 21

What should normal haemoglobin levels be?

Answer 21

Normal haemoglobin =

120 - 160 g/L

Question 22

What are the features of a delayed haemolytic reaction? Clinical and lab features.

Answer 22

After transfusion haemoglobin will rise as expected. 3 -1 4 Days later condition deteriorates.

Clinical features:

1) fatigue
2) jaundice
3) fever

Lab findings:

1) drop in Hb
2) increase indirect
3) bilirubin

Question 23

What is the anti-human globulin test? ie. Coomb’s tes?

Answer 23

Coomb’s test is an investigation to detect incomplete !gG antibodies.

Question 24

What is transfusion related acute lung injury and how does it occur?

Answer 24

TRALI occurs within 6 hours of a transfusion and causes hypoxemia.

The antibodies in the donor blood activated the recipient’s WBCs. These activated WBCs lodge in pulmonary capillaries and release substances which cause endothelial damage and capillary leak.

Question 25

How does transfusion associated circulatory overload (TACO) presenting signs / symptoms ?

Answer 25

TACO:
presentation:
1) sudden dyspnea (SoB)
2) Orthopnoea (SoB when flat)
3) Tachycardia
4) Hypertension
5) Hypoxemia
6) RAISED BP
7) ELEVATED JUGULAR VENOUS PULSE

Question 26

What are the risk factors of Transfusion associated circulatory overload (TACO)

Answer 26

TACO Risk factors:

1) Elderly patients
2) Small children
3) compromised LV function
4) increased transfusion volume
5) increased rate of transfusion

Question 27

What are the differences between TACO and TRALI?

TACO = Transfusion associated circulatory overload.

TRALI = Transfusion related acute lung injury

Answer 27

1) BLOOD PRESSURE:
TACO = Raised
TRALI = Reduced

2) TEMPERATURE
TACO = Normal
TRALI = Raised

3) DIURETICS:
TACO = improve
TRALI = worsen

Question 28

What allergic reactions are associated with transfusion?

Answer 28

1) URTICARIAL RASH (with wheeze)

2) ANAPHYLAXIS
wheeze, asthma, hypotensive/shock
+Oedema