The efficacy and safety of an adapted opioid-free anesthesia regimen versus conventional general anesthesia in gynecological surgery for low-resource settings: a randomized pilot study

Abstract

Introduction: There is scarce data on the safety and efficacy of opioid-free anesthesia (OFA), in resource-limited settings due to the non-availability of dexmedetomidine, the reference OFA agent. We aimed to demonstrate the feasibility, efficacy and safety of a practical OFA protocol not containing dexmedetomidine, adapted for low-resource environments in very painful surgeries like gynecological surgery.

Methods: We conducted a randomized pilot study on ASA I and II women undergoing elective gynecological surgery at a tertiary care hospital in Cameroon. Patients were matched in a ratio of 1:1 into an OFA and a conventional general anesthesia (CGA) group. The OFA protocol entailed the intravenous (IV) magnesium sulfate, lidocaine, ketamine, dexamethasone, propofol, and rocuronium, followed by isoflurane and a continuous infusion of a calibrated mixture of magnesium sulfate, ketamine and clonidine. The CGA protocol was IV dexamethasone, diazepam, fentanyl, propofol, and rocuronium, followed by isoflurane and reinjections of fentanyl propofol and a continuous infusion of normal saline as placebo. The primary endpoints were the success rate of OFA, isoflurane consumption and intraoperative anesthetic complications. The secondary endpoints were postoperative pain intensity, postoperative complications, patient satisfaction assessed using the QoR-40 questionnaire and the financial cost of anesthesia.

Results: We enrolled a total of 36 women undergoing gynecological surgery; 18 in the OFA group and 18 in the CGA group. The success rate of OFA was 100% with significant lesser consumption of isoflurane in the OFA group, no significant intraoperative complication and better intraoperative hemodynamic stability in the OFA group. Postoperatively, compared to the CGA group, the OFA group had statistically significantly less pain during the first 24 h, no morphine consumption for pain relief, had less hypoxemia during the first six hours, less paralytic ileus, less nausea and vomiting, no pruritus and better satisfaction. The mean financial cost of this adapted OFA protocol was statistically significant lesser than that of CGA.

Conclusion: This OFA regimen without dexmedetomidine for a low-resource setting has a promising success rate with few perioperative complications including mild intraoperative hemodynamic changes, decrease postoperative complications, pain, and opioid consumption in patients undergoing elective gynecology surgery.

Trial registration: This study was registered at clinicaltrials.gov on 03/02/2021 under the registration number NCT04737473.

Keywords: Adapted; Cameroon; Efficacy; Gynecological surgery; Opioid-free anesthesia; Safety.

Fig. 1

CONSORT 2010 flow diagram illustrating participants’ enrollment

Fig. 2

Means of mean arterial pressures intraoperative variations between the OFA and CGA groups

Fig. 3

Intraoperative consumption of halogen gazes in the OFA and CGA groups

Fig. 4

Postoperative pain intensity variations in the OFA and CGA groups. NRS = 7 at 1^st hour occurred only in mastectomies and hysterectomies. NRS was statistically different at 12 h and 24 h mainly in mastectomies

Fig. 5

Means of postoperative peripheral oxygen saturation variations between the OFA and CGA groups