Alternatives to allogeneic blood use in surgery: acute normovolemic hemodilution and preoperative autologous donation.

Acute normovolemic hemodilution (ANH) is a common blood conservation strategy in elective surgical procedures. Moderate ANH is safe in patients > 60 years of age; ANH is not recommended for patients who have coronary artery disease, significant anemia, renal disease, severe hepatic disease, pulmonary emphysema, or obstructive lung disease. Preservation of oxygen delivery during ANH depends on the maintenance of normovolemia to avoid decompensation and falling cardiac output. Preoperative autologous donation (PAD) as a blood conservation strategy has the advantage of protecting the patient from risks associated with allogenic transfusion, but it is expensive and time consuming. No protocols have established a preference for either ANH or PAD; an early study suggested that ANH is less expensive and more effectively preserves blood components, but other researchers warn that the methodology for ANH remains unresolved.