To evaluate the analgesic effect of intraoperative continuous lidocaine infusion (1.5 mg/kg/h (ideal body weight)) in combination of analgesia nociception index and depth of anesthesia monitors guided anesthetics adjustment on enhanced recovery after surgery (ERAS) in patients undergoing elective lumbar spine surgery (≥2 sessions).

The patients undergoing elective lumbar spine surgery (≥2 sessions) are randomly assigned and divided patients into two groups according to the allocation sequence table (corresponding to 1:1 randomization) generated by the computer. Patients in the lidocaine group receive an intravenous injection of 1.5 mg/kg lidocaine at induction of anesthesia and continuous infusion of 1.5 mg/kg/h (ideal body weight) through the maintenance period to one hour after operation. Patients in control group receive the same volume of saline injection. During the operation, the dose of anesthetic drugs (propofol, remifentanil and rocuronium) are adjusted to maintain the mean arterial pressure and heartbeat fluctuations within 20% of the baseline value, Entropy (or BIS) value at 40-60, and ANI at 50-70 in both groups. The pain score (numerical rating scale), cumulative amount of opioids used after the operation within 3 days, and the quality of recovery on the third day after the operation are recorded and analyzed.

Inclusion Criteria:

1. Twenty to eighty-year-old
2. ASA class I-III patients undergoing
3. Elective lumbar spine surgery under general anesthesia

Exclusion Criteria:

1. Unable to understand the Numerical Rating Scale (NRS)
2. Severe mental disorder
3. Poor liver function
4. Pregnant or lactating women
5. Morbidly obese
6. History of epilepsy or allergy to any of the drugs used in this study
7. Current use of opioids
8. Baseline heart rate <50 beats/min
9. Arrhythmia history with cardiac rhythm device
10. Body weight <40 kg and >80kg