Effect of Opioid-Free Versus Opioid-Based Anesthesia in Discectomy Surgery

Postoperative Pain Intensity

Opioid-free, Opioid-based, dexmedetomidine, Ketamine, fentanyl

This prospective randomized double-blind clinical trial compares opioid-free anesthesia (OFA) versus opioid-based anesthesia (OBA) on postoperative analgesia in patients undergoing elective lumbar discectomy surgeries at Zagazig University Hospitals. Forty-six adult patients (ASA I-II, aged 21-64) will be randomly allocated to two groups. Group F (OFA) receives dexmedetomidine (loading 1 µg/kg, infusion 0.2-0.7 µg/kg/hr) and ketamine (0.25-0.5 mg/kg, infusion 0.1-0.3 mg/kg/hr). Group B (OBA) receives fentanyl (2 µg/kg bolus, 1 µg/kg/hr infusion). Both groups receive propofol maintenance. Primary outcome is postoperative pain intensity measured by Visual Analog Scale (0-10) at baseline, 2, 6, 12, and 24 hours. Secondary outcomes include total analgesic consumption in 24 hours, time to first rescue analgesia, intraoperative hemodynamic stability (BP, MAP, HR, RR), recovery time (to responsiveness), sedation depth (Modified Ramsay Score), PACU discharge time, patient satisfaction, and incidence of opioid-related adverse effects (nausea, vomiting, respiratory depression). The study hypothesizes that OFA provides comparable analgesia with fewer opioid-related complications. As the first such study at Zagazig University, it addresses the critical need for effective non-opioid pain management in spine surgery, contributing to safer practices amid global opioid concerns.

Study Design and Methodology: This is a single-center, prospective, randomized, double-blind, parallel-group, active-controlled clinical trial. A total of 46 adult patients scheduled for elective lumbar discectomy surgery under general anesthesia at Zagazig University Hospitals will be enrolled. Participants will be randomly assigned in a 1:1 ratio to one of two treatment arms using computer-generated randomization. The study will employ double-blinding where both participants and outcome assessors will be unaware of group assignments. Intervention Protocols: Opioid-free Anesthesia (OFA) Group: Patients will receive a multimodal non-opioid regimen consisting of: dexmedetomidine loading dose 1 µg/kg intravenous (IV) over 10 minutes before induction, followed by continuous infusion at 0.2-0.7 µg/kg/hr; ketamine 0.25-0.5 mg/kg IV at induction, followed by infusion at 0.1-0.3 mg/kg/hr; and propofol infusion (4-12 mg/kg/hr) for anesthesia maintenance. Opioid-based Anesthesia (OBA) Group (Active Comparator): Patients will receive fentanyl 2 µg/kg IV at induction, followed by continuous infusion of 1 µg/kg/hr, along with propofol infusion (4-12 mg/kg/hr) for maintenance. Both groups will receive standardized premedication (pantoprazole 40 mg, ondansetron 4 mg), antibiotic prophylaxis, neuromuscular blockade with atracurium, and reversal with neostigmine and atropine. Intraoperative ventilation parameters will be adjusted to maintain EtCO₂ between 35-40 mmHg. Postoperative Management: All patients will receive scheduled postoperative analgesia with paracetamol 1 g every 6 hours and intramuscular diclofenac 75 mg (maximum 150 mg/day). Rescue analgesia with IV nalbuphine (0.1-0.2 mg/kg, maximum 160 mg/day) will be administered for Visual Analog Scale (VAS) scores \>3. Pain assessment will occur at baseline (immediate postoperative), 2, 6, 12, and 24 hours postoperatively. Data Collection and Assessment: Data will be collected preoperatively (demographics, medical history), intraoperatively (hemodynamic parameters, drug consumption), and postoperatively (pain scores, sedation levels, analgesic requirements, adverse events). Sedation will be assessed using the Modified Ramsay Sedation Score at 2-hour intervals for the first 12 hours, then every 4 hours for the next 12 hours. Hemodynamic stability will be monitored by recording blood pressure, mean arterial pressure, heart rate, and respiratory rate at predefined intervals. Statistical Considerations: Sample size calculation was based on detecting a difference in VAS scores between groups, with 80% power and 95% confidence level, yielding 42 patients plus 4 additional (10% dropout compensation), totaling 46 participants (23 per group). Data analysis will be performed using SPSS version 20.0, with appropriate statistical tests (t-tests, ANOVA, chi-square) and correction for multiple comparisons using Benjamini-Hochberg False Discovery Rate. Ethical and Regulatory Aspects: The study protocol has been submitted for approval to the Zagazig University Institutional Review Board (IRB). Written informed consent will be obtained from all participants. Patients retain the right to withdraw from the study at any time without affecting their medical care. The study will comply with Good Clinical Practice guidelines and the Declaration of Helsinki. Study Duration and Timeline: The total study duration is anticipated to be 6 months, including patient recruitment, intervention, follow-up, and data analysis. Results will be disseminated through academic publication and presentation.

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