Using the nociception level index to compare the intraoperative antinociceptive effect of propofol and sevoflurane during clinical and experimental noxious stimulus in patients under general anesthesia

Abstract

Study: Propofol and sevoflurane are two anesthetic agents widely used to induce and maintain general anesthesia (GA). Their intrinsic antinociceptive properties remain unclear and are still debated.

Objective: To determine whether propofol presents stronger antinociceptive properties than sevoflurane using intraoperative clinical and experimental noxious stimulations and evaluating postoperative pain outcomes.

Design: A prospective randomized monocentric trial.

Setting: Perioperative care.

Patients: 60 adult patients with ASA status I to III who underwent elective abdominal laparoscopic surgery under GA were randomized either in propofol or sevoflurane group to induce and maintain GA.

Interventions: We used clinical and experimental noxious stimulations (intubation, tetanic stimulation) to assess the antinociceptive properties of propofol and sevoflurane in patients under GA and monitored using the NOL index, BIS index, heart rate, and mean arterial blood pressure.

Measurements: We measured the difference in the NOL index alterations after intubation and tetanic stimulation during either intravenous anesthesia (propofol) or inhaled anesthesia (sevoflurane). We also intraoperatively measured the NOL index and remifentanil consumption and recorded postoperative pain scores and opioid consumption in the post-anesthesia care unit. Intraoperative management was standardized by targeting similar values of depth of anesthesia (BIS index), hemodynamic (HR and MAP), NOL index values (below the threshold of 20), same multimodal analgesia and type of surgery.

Main results: We found the antinociceptive properties of propofol and sevoflurane similar. The only minor difference was after tetanic stimulation: the delta NOL was higher in the sevoflurane group (39 ± 13 for the propofol group versus 47 ± 15 for sevoflurane; P = 0.04). Intraoperative and postoperative pain outcomes and opioid consumption were similar between groups.

Conclusions: Despite a precise intraoperative experimental and clinical protocol using the NOL index, propofol does not provide a higher level of antinociception during anesthesia or analgesia after surgery when compared to sevoflurane. Anesthesiologists may prefer propofol over sevoflurane to reduce PONV or anesthesia-related pollution, but not for superior antinociceptive properties.