QuestionSBA
QuestionChoice
Anaemia can cause shortness of breath and hypoxia, but it is unlikely that this would develop only after the transfusion - if the anaemia were significant enough to cause these symptoms, you would expect them to have been present both **before** _and after_ the transfusion
33446
d
Persistent anaemia requiring further transfusion
QuestionChoice
In older, more frail patients, extra care and caution must be taken to avoid fluid overload when giving any infusion. We are used to considering this and adapting our prescriptions accordingly when giving simple fluids, but this can be overlooked when giving blood products. It is important to remember that blood products can have similar effects to fluids, particularly when multiple units are required. You can reduce the risk of transfusion associated circulatory overload by giving the blood products more slowly (i.e. giving 1 unit over 4 or 5 hours, instead of 2 or 3) or by giving a small dose of furosemide between each unit
33443
a
Transfusion associated circulatory overload
QuestionChoice
Complications of transfusions that are classified as "delayed" occur days to weeks following the transfusion event. As the onset of the patient's symptoms started only 2 hours after completing the transfusion, this would not be classified as a 'delayed' reaction. Additionally, there is no evidence in the stem to point you towards haemolysis (features of a haemolytic reaction may include jaundice, fever, elevated lactate dehydrogenase +/- bilirubin, a newly positive direct antiglobulin test on blood testing and haemoglobinuria)
33447
e
Delayed haemolytic transfusion reaction
QuestionChoice
There is no mention in the stem of infective symptoms to meet criteria for sepsis, such as fever, tachycardia or hypotension. With modern screening of blood products, acquiring an infection from a transfusion is rare. Although it is always important to consider when reviewing a patient with complications from a transfusion, it is not the most likely cause of this patients symptoms
33444
b
Transfusion associated sepsis
QuestionChoice
Anaphylactic reactions to blood products are rare. If this were to be the case, you would expect more of a focus on key anaphylactic symptoms, including the airway being affected (new wheeze, stridor, airway swelling) or features of anaphylactic shock, including significant hypotension. The biggest risk factor for transfusion associated anaphylaxis is IgA deficiency, following receipt of transfused plasma containing normal IgA levels
33445
c
Anaphylactic reaction
Concept
Chapter
# Summary

Blood comprises two core components: cellular elements and plasma. Cellular components consist of white blood cells (neutrophils, eosinophils, basophils, monocytes, lymphocytes), red blood cells (RBCs or erythrocytes), and platelets (thrombocytes). Plasma encompasses clotting factors, albumin, and immunoglobulins. Blood groups, notably ABO and Rh, influence transfusion compatibility, with group O individuals universal donors. Acute and late transfusion reactions require vigilant monitoring and management. Iron overload can result from frequent transfusions, necessitating interventions to lower iron levels.

# Blood Components

Blood is made of two main components: cells and plasma

- The cellular components of blood include: 
  - white blood cells (neutrophils, eosinophils, basophils, monocytes, lymphocytes)
  - RBCs (erythrocytes) 
  - platelets (thrombocytes)

- Plasma consists of: 
  - clotting factors
  - albumin 
  - immunoglobulins

## Lifespan of components

The normal lifespan of the following cellular components of blood is:

- RBCs, 90–120 days
- platelets, 10 days
- neutrophils, 4 days

## Products for transfusion

Four products are readily transfusable:

- **Red blood cells**
  - Generally **stored at 4 °C** for up to 35 days 
  - In vivo, RBCs typically have a lifespan of about 120 days; however, it is important to note that transfused red cells last around 50–60 days


- **Fresh frozen plasma** (FFP)
  - **Stored at –30 °C**, with a shelf life of a year
  - Used in patients with coagulopathy (impaired blood coagulation) to replace clotting factors
  - The type of FFP used depends on the patient's blood group


- **Platelets**

  - **Stored at room temperature** for up to 7 days
  - Have a lifespan of 10 days before they are phagocytosed in the spleen and liver
  - 1 pool of platelets comes from 4 donors
  
  
    - Platelets are given if levels are <10 x 10<sup>9</sup>/l in patients with thrombocytopenia due to marrow failure from chemotherapy and radiotherapy – This threshold can be increased if there is sepsis or bleeding, or for a planned surgical procedure 
  
  
    - Platelet transfusions should not be used in conditions where there is immune destruction of platelets (eg. immune thrombocytopenia unless there is a haemorrhagic emergency)
  
  
    - Platelet transfusion is also contraindicated in TTP or HUS as it can contribute to the microvascular occlusion in the brain and kidneys that is associated with these conditions
  


- **Cryoprecipitate**

  - Cryoprecipitate is made by thawing FFP overnight at 4–8 °C
  - It has a shelf life of 1 year **stored at –30 °C**
  - It contains fibrinogen, factor VIII and von Willebrand factor
  - It is generally used in patients with massive bleeding and low fibrinogen

# Blood Groups

* Blood groups, defined as antigens on the surface of red blood cells, are critical in determining blood compatibility for transfusions. 
* There are over 400 blood groups but the ABO and Rh blood groups are the most important, each with distinct inheritance patterns. 
* The ABO antigens develop on red cells 16 weeks after birth, meaning neonates do not require blood cross-matching for transfusions. 
* Adults with group O red cells can universally donate due to the absence of A or B antigens, and group AB plasma can be universally donated due to the lack of anti-A or anti-B antibodies.
* The A and B genes show co-dominant inheritance, whereas the O gene is recessive.

# Antigens and Compatibility

* **Rhesus antigen** - The Rh group includes 5 main antigens with Rhesus D being the most important. The Rhesus D antigen has an autosomal dominant mode of inheritance.
- **ABO antigens** - not expressed on red cells until 16 weeks after birth. Therefore, in neonates, there is no need to cross-match for blood transfusions as antibodies are not yet made.

Please see the summary table below on blood group compatibility and donation:


| Blood Type | Can Receive From | Can Donate To |
|------------|-----------------|--------------|
| A+         | A+, A-, O+, O-   | A+, AB+      |
| A-         | A-, O-           | A+, A-, AB+, AB- |
| B+         | B+, B-, O+, O-   | B+, AB+      |
| B-         | B-, O-           | B+, B-, AB+, AB- |
| AB+        | All Blood Types  | AB+          |
| AB-        | AB-, A-, B-, O-  | AB+, AB-     |
| O+         | O+, O-           | A+, B+, AB+, O+  |
| O-         | O-               | All Blood Types  |

# Acute Transfusion Reactions

## Allergy 

- Presentation ranges from urticaria to angioedema and anaphylaxis
- Management – stop the transfusion if concerns over anaphylaxis (if mild urticaria, can slow the transfusion and give antihistamine), give saline, adrenaline (in case of anaphylaxis), chlorphenamine, and hydrocortisone

## Acute haemolytic transfusion reaction 

- Caused by giving an incompatible blood bag to a patient
- Early signs include fever, abdominal pain, hypotension and anxiety
- Late complications include generalised bleeding secondary to DIC
- Management – stop the transfusion, give saline, treat DIC

## Febrile non-haemolytic transfusion reaction 

British Society for Haematology guidelines recommend that: 

- In patients with a **mild** reaction:

 - A temperature rise of 1 - 2°C leading to pyrexia ≥38°C, but <39°C
 - And/or pruritus or a rash
 - WITHOUT other features

The transfusion can be continued with appropriate treatment (oral paracetamol 500 - 1000mg) and direct observation. If a rash/pruritis is also present, slow the transfusion)
 
- In patients who develop **moderate** reactions:
 - Temperature ≥39°C OR a rise of ≥2°C from baseline
 - AND/OR systemic symptoms such as chills, rigors, myalgia, nausea or vomiting)

Symptomatic treatment should be considered. If symptoms settle, the transfusion can be resumed. If symptoms are sustained, bacterial contamination or a haemolytic reaction should be considered.

## Transfusion-related acute lung injury (TRALI)

- Presents with pulmonary oedema and can cause acute respiratory distress syndrome (ARDS)

- Management – stop the transfusion, give saline, treat ARDS and give supplementary oxygen as needed

## Transfusion-associated circulatory overload (TACO)

- Presents with fluid overload

- Management – Slow the transfusion, give furosemide and supplementary oxygen as needed

# Late Transfusion Reactions

## Delayed haemolytic transfusion reaction 

- Caused by an exaggerated response to a foreign red cell antigen that the patient has been exposed to before
- Patients present with jaundice, anaemia, and fever, usually on day 5 post-transfusion

## Transfusion-associated graft-versus-host disease 

- Caused by donor blood lymphocytes attacking the recipient's body 
- Rare but carries a high risk of mortality

## Iron Overload

- Iron overload may be related to the pathophysiology of the condition (eg. haemochromatosis) or iatrogenic (eg. related to a blood transfusion or excess oral iron) 
  - There is no secretion pathway for iron and approximately 1 mg of iron is lost via gut mucosal cells
  - Absorption of luminal iron is mediated by enterocytes, which respond to iron stores in the body
  - The enterocyte is modulated via its transferrin receptor, which regulates transferrin uptake from the plasma
  - In turn, the HFE protein modulates transferrin receptor activity
- Iron overload usually becomes an issue after 20 units have been given or if serum ferritin rises above 1000 µg/l 
- Subcutaneous desferrioxamine is required regularly to lower iron levels

# References

[Click here to see more information on Patient UK about transfusion reactions](https://patient.info/doctor/blood-transfusion-reactions)

[Click here to see more information on the British Society for Haematology guidelines on acute transfusion reactions](https://onlinelibrary.wiley.com/doi/full/10.1111/bjh.18789)
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Blood Products, Groups and Transfusions
Topic
8
Haematology
6689
A 69-year-old male requires a 3 unit blood transfusion following a road traffic accident. He has no past medical history but appears physically very frail, weighing 49 kilograms with a body mass index of 17.

Two hours after the transfusion, he becomes increasingly short of breath and develops an oxygen requirement, needing 2 litres to maintain saturations of 96%.

What is the most likely cause of his respiratory symptoms?
a