Comparative study between the effect of opioid-free anesthesia versus opioid-based anesthesia in morbid obese patients

Introduction
Multimodal techniques for pain management involve using two or more analgesic drugs with different mechanisms of action working in synergy. These drugs may be given by either the same or different routes of administration preoperatively, intraoperatively, and/or postoperatively []. By targeting different pain pathways within the central and peripheral nervous systems, the use of multiple agents with different mechanisms of action allows for lower doses of individual agents, which in turn results in a lower risk of adverse effects.
Aim
We have conducted this study to compare the effect of opioid-free anesthesia (OFA) with opioid-based anesthesia (OA) on postoperative pain relief as a primary outcome and hemodynamic variables, including mean arterial blood pressure (MAP), heart rate (HR) and oxygen saturation%, total pethidin consumption 24 h postoperatively, and postoperative complications developed in postanesthetic care unit (PACU), such as hypoxia, shivering, nausea, and vomiting as secondary outcomes in morbid obese patients.
Patients and methods
A total of 40 patients (morbidly obese) aged 25–50 years with BMI of at least 35, having ASA status II scheduled for laparoscopic cholecystectomy were divided into two groups in a randomized controlled fashion: group 1 was the OA group (=20), which received general anesthesia with propofol, muscle relaxant (rocuronium), and fentanyl as the main anesthetic adjuvant and analgesic, and group 2 was the OFA group (=20), which received general anesthesia with propofol, muscle relaxant (rocuronium), dexmedetomidine, magnesium sulfate, and lidocaine as anesthetic adjuvant and analgesic. Hemodynamic variables such as MAP, HR, and oxygen saturation% were recorded preoperatively, postintubation, and every 15 min till the end of surgery. Postoperative visual analog scale done immediately postoperatively, and at 2, 6, 12, and 24 h postoperatively; total pethidine consumption in 24 h postoperatively; and postoperative complications developed in PACU such as hypoxia, shivering, nausea, and vomiting were also recorded for each patient.
Results
There were no differences between the two groups regarding demographic data. There was a statistically significant decrease in HR in OFA group compared with OA group from 15 min after induction to 15 min postoperatively and a statistically significant decrease in MAP in group II (OFA) compared with group I (OA) from 30 min after induction to 90 min postoperatively in PACU. Visual analog scale for pain postoperatively was lower in nonopioid group than opioid group. The postoperative pethidine consumption was significantly lower in OFA versus OA. Postoperative complications like nausea, vomiting, shivering, and hypoxia were significantly higher in the OA group.
Conclusion
OFA provides postoperative pain relief and intraoperative hemodynamic stability without significant associated adverse effects compared with OA.