Acute normovolemic hemodilution

Acute Normovolemic Hemodilution (ANH) is a blood management strategy often used in surgery to reduce the need for allogeneic blood transfusion. This technique involves the removal of the patient's own blood immediately before surgery, simultaneous replacement with a non-blood volume expander to maintain blood volume, and reinfusion of the collected blood during or after surgery.

Procedure

The ANH procedure begins with the patient's venous access being established. Blood is then withdrawn from the patient and collected in blood bags. The volume of blood removed varies depending on the patient's hemoglobin level, weight, and the anticipated blood loss during surgery. The withdrawn blood is replaced with a crystalloid or colloid solution to maintain the blood volume. The collected blood is then reinfused during or after surgery.

Benefits

The primary benefit of ANH is the reduction in the need for allogeneic blood transfusion, thereby minimizing the associated risks such as transfusion reactions, transfusion transmitted infections, and immunomodulation. ANH also ensures the availability of autologous fresh whole blood, which is superior to stored blood in terms of oxygen-carrying capacity and coagulation factors.

Risks and Limitations

While ANH is a useful technique, it is not without risks and limitations. The procedure requires skilled personnel and adds to the cost and duration of surgery. It may not be suitable for patients with cardiovascular disease, as the initial hemodilution can lead to decreased oxygen-carrying capacity. Furthermore, the effectiveness of ANH in reducing allogeneic blood transfusion is dependent on the surgical procedure and the patient's condition.

See Also

• Blood transfusion
• Autologous blood donation
• Intraoperative blood salvage