Acute Normovolemic Hemodilution
What is Acute Normovolemic Hemodilution?
Acute normovolemic hemodilution (ANH) is a medical technique where whole blood is removed from an individual and it is simultaneously replaced by a balanced salt solution or crystalloid via a different route. It is used in medical situations that require to reduce the blood viscosity and to minimize the requirement for stored blood or blood transfusion. This procedure is typically used in medical and surgical scenarios such as cardiopulmonary bypass, liver transplantation, craniotomy and other medical procedures.
Acute normovolemic hemodilution is a technique that allows surgical procedures to take place with less risk of blood loss from a patient. By removing some of the red blood cells from the body and replacing them with crystalloid, the blood volume remains the same but with a decrease in the viscosity of the blood. This reduces the chance of the patient losing too much blood and them needing a blood transfusion.
Benefits of Acute Normovolemic Hemodilution
The main benefits of ANH include:
- Reduced requirement for blood transfusions
- Decreased possibility of infection due to transfused blood products
- Reduction in the risk of blood-borne diseases
- Prevention of errors that could take place when cross-matching incompatible blood
- Reduction in the cost of both the harvesting and subsequent transfusion of blood
Risks of Acute Normovolemic Hemodilution
Although this technique is generally safe and well tolerated, there are potential risks to consider:
- Transient volume overload
- Hemolysis due to the citrate used as anticoagulant
- Infection from contaminated crystalloid replacement solutions
- Hypothermia or acid-base changes due to exchange of the crystalloid solution
- Air emboli if air is inadvertently infused into the replacement solution
- Reaction to inappropriate drugs, antibiotics or hormones given together with the replacement solution
Acute normovolemic hemodilution is an effective technique for reducing the requirement for blood transfusions and minimizing associated risks. While it is generally well tolerated and safe, it is important to weigh up the potential risks and benefits in order to determine whether it is the most appropriate procedure for a patient.