IoC2 monitoring versus standard practice in reducing opioid consumption in elderly patients undergoing laparoscopic colorectal surgery: a study protocol for a randomised controlled trial

Introduction Nociception monitoring has recently gained recognition as a valuable tool for guiding intraoperative opioid administration. Several nociception monitors, including the Surgical Pleth Index, the Index of Consciousness (IoC) and the Nociception Level, have been introduced for managing intraoperative analgesia. While these technologies show promise in initial applications, the effectiveness of IoC2 in guiding pain management during anaesthesia, particularly in elderly patients who require precise opioid use, remains unclear. This study aims to evaluate the effectiveness of IoC2 in guiding intraoperative opioid use in elderly patients.Methods and analysis We will conduct a prospective, randomised, controlled, single-blind, single-centre study with recruitment carried out from 1 February to 30 November 2025. Patients will be randomly assigned to either the IoC2 group or the control group. In the IoC2 group, sufentanil dosing will be guided by intraoperative IoC2 measurements, while in the control group, it will be guided by haemodynamic parameters. The primary outcome will be to compare intraoperative sufentanil consumption between the two groups to assess the potential role of IoC2 in optimising perioperative analgesia in elderly patients.Ethics and dissemination This study has been approved by the ethics committee of China-Japan Friendship Hospital (2024-KY-148-3) and registered in the Chinese Clinical Trial Registry (ChiCTR2400089115). The findings will be disseminated through academic presentations and peer-reviewed journal publications, providing valuable data and insights into the role of IoC2 in guiding intraoperative pain management.Trial registration number ChiCTR2400089115.