Inclusion Criteria:  Twenty to eighty-year-old ASA class I-III patients undergoing Elective lumbar spine surgery under general anesthesia  Exclusion Criteria:  Unable to understand the Numerical Rating Scale (NRS) Severe mental disorder Poor liver function Pregnant or lactating women Morbidly obese History of epilepsy or allergy to any of the drugs used in this study Current use of opioids Baseline heart rate <50 beats/min Arrhythmia history with cardiac rhythm device Body weight <40 kg and >80kg