Explain acute isovolemic hemodilution (AIHD).
AIHD is a procedure in which whole blood is removed during the perioperative period, while intravascular volume is maintained at a normal level by simultaneous infu-sion of crystalloid or colloid solutions. The blood, which is withdrawn into standard blood bags containing anticoagu-lant, is available for transfusion to the patient either during the operation or in the postoperative period. In this way, autologous whole blood containing red cells, clotting fac-tors, and platelets is available. Its advantages are summa-rized in Table 51.1.