Acute normovolemic hemodilution

Adequate volume replacement during major surgeries is mandatory in order to avoid organ 
dysfunction and death(1)
. The hazards related to homologous blood transfusion are well 
known, and might include: hypothermia, coagulation problems, hyperkalemia, hypocalcemia, 
allergic reactions, acute lung injury, hemolytic and non-hemolytic reactions, and transmitted 
infections(2)
.
Although multiple measures are performed to increase the safety of donated blood and/or 
products, autologous blood remains the safest source for blood transfusion(3)
. Autologous 
blood donation may be performed by either: pre-deposit autol- ogous transfusion (The 
patient donates blood 3–5 weeks before surgery to be used intraoperatively), intraoperative 
acute normovolemic hemodilution, or intraoperative red blood cell salvage(4)
.
Acute normovolemic (isovolemic) hemodilution (ANH) is a blood conservation technique 
which involves intraoperative removal and storage(at room temperature) of blood from a 
patient, just before or shortly after the induction of anesthesia, with simultaneous adding of 
a replacement volume of crystal- loid and/or colloid(5)
. This blood is transfused again to the 
same patient when intra-operative blood loss is controlled, or when necessary(6)
.
ANH is indicated when blood loss is expected to be more than 1 or expected to exceed 20% 
of the patients’ blood volume(7)
.
The American Association of Blood Banks guidelines recommend that intraoperative or 
postoperative autotransfusion should be performed in surgeries where a large amount of 
bleeding (more than 20% total volume) is anticipated(8)
.
In summary, compared with allogeneic blood transfusion, ABT has irreplaceable advantages 
such as avoiding allergies, immunosuppression, hemocytolysis and other adverse reactions. It 
is a safe, effective and affordable method of blood transfusion(9)
.