Abstract: Objective To evaluate the clinical profile of ANI-guided remifentanil administration during posterior lumbar spinal surgery. Methods 60 patients undergoing selective posterior lumbar decompression laminectomy and internal fixation were randomized into two groups, ANI-guided analgesia group (ANI group) and another group which was blinded to ANI (control group).In both groups, combined propofol-remifentanil target control infusion(TCI) were performed, In ANI group, the concentration of remifentanil was adjusted to maintain ANI values between 50 and 70, however, in the control group, remifentanil target concentration was adapted corresponding to HR or BP values. Anesthetics consumption, incidence of unwanted events, interventions, time of open-eyes and extubation, VAS0h and VAS1/2h, complementary analgesics, intraoperative awareness, PONV and other symptoms were recorded. Results Remifentanil consumption was lower in ANI group than that in control group (P＜0.05).The number of unwanted events(hypotension, bradycardia and total unwanted events ) were also less in ANI group than that in control group (P＜0.05). Compared with control group, the usage of urapidil was more and the usage of volume expansion was less in ANI group(P＜0.05). There were no significant statistic differences in other index between two groups. Conclusion ANI-guided remifentanil infusion resulted in lower remifentanil administered dose and more stable hemodynamics in posterior lumbar spinal surgery.

Key words: analgesia nociception index, heart rate variability, bispectral index, general anesthesia