Analgesia Nociception Index in Orthognathic Surgery

• Analgesia/Nociception Index (ANI) monitoring (Device): intraoperative analgesia was provided by infusion of remifentanil via target controlled infusion mode, which was controlled according to ANI monitor.
• Standard monitoring (Device): intraoperative analgesia was provided by infusion of remifentanil via target controlled infusion mode, which was controlled according to the clinician's decision

Primary outcomes

• Postoperative QoR-15K score [24 hours after the end of surgery]: Korean-translated QoR-15K (15-item Quality of Recovery (QoR-15) scale, minimum 0, maximum 150, higher scores mean a better outcome ) scores assessed by participants blinded to arm assignment 24 hours after surgery.

Secondary outcomes

• Patient satisfaction [24 hours after the end of surgery]: Postoperative satisfaction as assessed by study participants blinded to group assignment, recorded on an NRS scale from a low of 0 to a high of 10.
• intraoperative opioid consumption [during surgery]: total dose of remifentanil consumption during surgery
• intraoperative non-opioid consumption [during surgery]: total dose of non-opioid consumption during surgery
• intraoperative use of vasoactive drugs [during surgery]: total dose of vasoactive drugs during surgery
• The time-weighted average of the segments of the total anesthesia time where the ANI value did not remain above 50 and below 70. [during surgery]
• Percentage of time with a deviation of more than ±20% from the mean blood pressure measured on the ward as a percentage of total anesthesia time [during surgery]
• estimated blood loss [during surgery]
• total fluid administration during surgery [during surgery]
• extubation time [from the end of surgery to endotracheal tube extubation, up to 30 minutes]
• number of participants with postoperative nausea vomiting [24 hours after the end of surgery]
• number of participants with postoperative opioid-related side effects (constipation, pruritis, dizziness, dry mouth, somnolence) [24 hours after the end of surgery]
• Total postoperative opioid consumption [24 hours after the end of surgery]
• Total postoperative non-opioid consumption [24 hours after the end of surgery]
• postoperative pain measured by numerical rating scale (NRS) scale (minimum 0, maximum 10, higher scores mean worse outcome) [24 hours after the end of surgery]

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Adult patients 18 or older undergoing maxillary, mandibular, or bimaxillary surgery under general anesthesia.
* adult patients who can provide written informed consent to participate in the study, understand the procedures of this study, and be able to complete patient-reported questionnaires adequately.
* adult patients who Have made an informed decision to participate in this study and have given written consent.

Exclusion Criteria:

* Patients with ASA physical status 4-5
* Emergency surgery
* Patients with chronic pain and related pain medications
* Patients with hypersensitivity to general anesthesia drugs and pain medications
* Patients with arrhythmia
* Pregnant women
* Others deemed unsuitable by the investigator