Written by: Zak Shah, 3rd Year Medical Student, UCL. 

Safe Monitoring of Blood Transfusions

Blood transfusions are often used when someone’s blood is lacking red blood cells, meaning their body is unable to perfuse tissues properly. This may be needed in someone who is haemorrhaging (bleeding profusely) or in patients with blood diseases such as sickle cell anaemia, for example. There are several types of transfusion, with the most common being red cell transfusions. This donates haemoglobin to the patient, allowing more oxygen to be delivered to tissues. Platelets or plasma (the liquid part of the blood) can also be individually transfused to reduce bleeding in certain patients (e.g., patients with low platelets due to chemotherapy) or to help in trauma patients, respectively.

Patients who have sickle cell anaemia have red blood cells that are not shaped like the normal donut-shaped red blood cells – instead, they are more curved and thinner. This means that they are less adapted to carry oxygen around, which can result in severe pain and organ damage. These patients will need to regularly receive someone else’s red blood cells to make up for their lack of healthy cells via red cell transfusions.

Blood Grouping

Red Blood cells contain surface glycoproteins that vary between people. These act as antigens.
There are A antigens (N-acetylgalactosamine glycoprotein added to the RBC)
B antigens (a molecule known as D-galactose is added to the RBC)
Patients can have both antigens – known as AB
Patients with no antigens have the O blood type.
Additionally, there is a further molecule known as the rhesus antigen that is present in some people’s red blood cells but not others.
This gives rise to the blood types such as A+, O- etc., with the first letter referring to the different antigen that is present and the +/- referring to whether the patient has the rhesus antigen.
When giving a blood transfusion, it is important to check the patient’s blood type matches the donor’s blood. If the patient’s blood type is incompatible with the donor’s blood, the patient’s immune system will attack the donor’s blood, leading to a severe reaction known as Acute Immune Haemolytic Reaction (AHTR).

Even if you match a patient’s blood type correctly, there is still a small chance that they may develop transfusion immune reactions. Therefore, it is important to monitor a patient’s vital signs before, during and after a transfusion. If a patient has a reaction, the transfusion should be stopped, and the patient can be treated by giving IV fluids.