3 Jan 2024
Gerardo Poli
Job Title
I get asked frequently when is the right time to transfuse an anaemic patient?
The difficulty lies in the fact not all anaemic patients require blood transfusions. Just because a patient has pale mucous membranes does not mean the patient needs a transfusion.
The term commonly brought up during the discussion is “transfusion triggers present”.
A couple of different definitions exist: classically, it is the PCV or haemoglobin level at which a transfusion is indicated in an individual animal – essentially, if it gets below a certain number, transfusion is required – but it is not always that simple. Just because the PCV is 15%, it doesn’t always mean a transfusion is required.
When the PCV drops low enough, clinical signs of reduced oxygen delivery to the tissues start to develop, these include:
These clinical signs are influenced by the speed at which the anaemia has developed.
If the anaemia has occurred rapidly due to internal bleeding from trauma or a ruptured organ, these clinical signs can present in a matter of minutes, depending on how big the bleed is. This means a transfusion might be indicated when the PCV is still 25%, especially if further rapid blood loss is likely.
If the anaemia developed over days to weeks (slow red cell destruction or anaemia of chronic disease, for example) transfusion triggers might not be present until the PCV drops below 15%, as the body has had time to compensate.
So, in summary, the decision-making process involves asking the questions:
When you combine the core aspects of each of the questions above, “transfusions triggers” change from absolute numbers to this:
Blood products you should use and why will be covered in a future post.
Note: Haemoglobin levels should also be assessed in conjunction with the PCV.
