This prospective randomised clinical trial aims to assess the impact of intraoperative nociception monitoring using NOL on anesthetic management during major abdominal surgery. Additionally, the study will objectively evaluate using NOL how intravenous lidocaine administration, influences opioid requirements and the effect of this multimodal approach on early postoperative outcomes. The investigators hypothesize that NOL-guided intraoperative opioid administration reduces both intraoperative and postoperative opioid use, positively influencing 24-hour outcomes. Furthermore, the addition of intraoperative lidocaine in NOL-guided analgesia may further decrease opioid consumption.

Inclusion Criteria:

• age > 18 years
• ASA score I-III
• surgery for gastric or hepatobiliary or pancreatic neoplasia

Exclusion Criteria:

• pregnancy
• lactation
• neuraxial or regional anesthesia
• chronic treatment with drugs that can influence autonomic nervous system
• diuretics or nitroglycerin administration on the day of surgery
• severe neurological disability
• severe hemodynamic instability
• chronic pain
• chronic opioid treatment
• allergy to any of the study drugs
• severe untreated disease or organ failure
• pacemaker
• emergency surgery
• patient refusal to participate