Acute normovolemic hemodilution, also called s intraoperative hemodilution is a blood conservation process where blood of the patient is removed before or shortly after induction of anesthesia and volume is maintained using crystalloid and/or colloid replacement.
The amount of blood removed varies between one and three units (450 to 500 mL = 1 unit) usually.
The withdrawn blood is anticoagulated and maintained at room temperature, in the operating room, for up to eight hours. It is reinfused into the patient as needed during, or after, the surgical procedure.
Acute normovolemic hemodilution should be considered for patients with good initial hematocrits and who are expected to lose more than two units of blood.
ANH is contraindicated in the following settings:
- Cardiac disease
- Impaired renal function
- Low hemoglobin
- Low serum proteins
- Inadequate vascular access
- Inadequate monitoring capability.