Indications for Blood Transfusions

Introduction

Blood transfusions are vital for patients in a critical condition to maintain tissue perfusion and oxygenation. Whole blood transfusions are commonly carried out in general practice in emergency situations, and blood products are also becoming more widely available.

Blood products are extremely useful in replacing specific blood compononent defecits and increasing the safety of transfusion therapy. Any severe haematological emergency would be an indication for the transfusion of blood products, but the four main indications are anaemia following haemolysis or haemorrhage (give RBCs), coagulopathies, thrombocytopaenia (use platelets) and hypoproteinaemia (use plasma). Animals with a history of previous transfusions or transfusion reactions should be given blood products in preference to whole blood where possible.

The decision to give a patient a blood transfusion depends on a number of factors. There is no threshold packed cell volume (PCV) value however any patient with a PCV lower than 20% in combination with signs of major hypoxia including tachycardia, bounding peripheral pulses, tachypnoea, collapse, weakness and lethargy requires a transfusion.

Other indications for tranfusion include:

• If the fall in PCV is sudden and combined with hypovolaemia.
• If acute haemorrhage does not respond to fluid therapy.
• If there is a sudden loss of more than 30% of blood volume.

• When a coagulopathy is present prior to surgery or is resulting in spontaneous haemorrhage.
• If platelet levels drop below 10000/ul or if thrombocytopaenia is present with spontaneous haemorrhages.

• If protein levels drop below 3.5g/dl or albumin levels drop below 1.5g/dl.
• If signs of oedema (e.g ascites) are occuring due to hypoproteinaemia.

In order to achieve a safe blood transfusion blood typing and sometimes crossmatching of the donor and recipient animal is required.

See also:

Administering a Blood Transfusion Blood Groups Blood Groups - Dog Blood Groups - Cat Blood Products

References

Transfusion Therapy. Lymphoreticular and Haematology module. 4th year notes. Royal Veterinary College London. 2009.

Selected Topics in Canine and Feline Emergency Medicine. Volume 1. Handbook for the veterinary practitioner. Royal Canin.