Purpose: This study was designed to investigate the effect of bispectral index (BIS) monitoring on the recovery profiles, level of postoperative cognitive dysfunction, and anesthetic drug requirements of elderly patients undergoing elective orthopedic surgery with general anesthesia.
Methods: Sixty-eight patients over the age of 60 were randomized into one of two groups. In the standard practice (SP) group, the anesthesiologists were blinded to the BIS value, and isoflurane was titrated according to standard clinical practice. In the BIS group, isoflurane was titrated to maintain a BIS value between 50-60.
Results: The total isoflurane usage was 30% lower in the BIS group compared to the SP group (5.6 +/- 3 vs 7.7 +/- 3 mL, P <0.05). The time to orientation was faster in the BIS group compared to the SP group (9.5 +/- 3 vs 13.1 +/- 4 min, P <0.001). There were no differences in the postoperative psychometric tests between the two groups.
Conclusions: There was no difference in the level of postoperative cognitive dysfunction between the two groups. However, titration of isoflurane using the BIS index decreased utilization of isoflurane and contributed to faster emergence of elderly patients undergoing elective knee or hip replacement surgery.