Abstract: AIM: To observe the effect of acute normovolemic hemodilution (ANH) autologous blood transfusion on the EEG bispectral index and muscle relaxation in elderly patients undergoing orthopedic surgery to explore the influence of autologous blood transfusion containing anesthetic components on the quality and safety of postoperative anesthesia recovery. METHODS: Forty patients, aged 65-75, weighing 55-80 kg, ASA grade I-II, with an estimated intraoperative blood loss of more than 600 mL, were selected for elective orthopedic surgery. The patients were randomly divided into two groups (n=20): group A was given acute normovolemic hemodilution (ANH), and the target value of Hct was 28%-30% after induction of anesthesia; group B was the control group which was given routine fluid infusion during operation without ANH. Bispectral index (BIS), TOF values and plasma concentrations of propofol and cisatracurium were measured at the beginning of autotransfusion (T1), 10 min (T2), 20 min (T3), 30 min (T4), 40 min (T5), 50 min (T6) and 60 min (T7) of autologous blood transfusion. The changes of blood gas before operation (T0) and at T7 time point were observed and recorded. The time of extubation of tracheal tube and the quality of recovery were observed. RESULTS: The BIS value of group A was significantly lower than that of group B at T6 and T7 (P<0.05), and the TOF value of group A was significantly lower than that of group B at T5, T6 and T7 (P<0.05); there was no significant difference between the blood concentrations of propofol and cisatracurium between group A and group B (P>0.05); the lactic acid value of group A at T7 was significantly higher than that of group B (P<0.05); the time of tracheal extubation in group A was significantly longer than that in group B (P<0.05); the Aldrete score of group A was significantly lower than that of group B (P<0.05). CONCLUSION: For patients with acute normovolemic hemodilution, autologous blood transfusion after operation can deepen the depth of anesthesia, enhance muscle relaxation effect, and delay the recovery of respiratory function and extubation time in elderly patients.

Key words: acute normovolemic hemodilution, EEG bispectral index, muscle relaxant effect, plasma drug concentration, autologous blood transfusion