Abstract:Effective perioperative pain management is essential for accelerating recovery and minimizing adverse events, in which sensitive and reliable pain monitoring plays an indispensable role. The index of consciousness (IoC) derived from electroencephalogram signal is an emerging index for monitoring the depth of anesthesia, and has been progressively applied during general anesthesia. The IoC2, is used for the monitoring of the degree of analgesia, and can be used as a pain management monitoring index in a variety of surgical types to evaluate the analgesic effect, guiding the rational use of analgesic drugs, and reducing perioperative-related adverse events. I it has good advantages and application prospects in the clinic. The purpose of this paper is to summarize the basic principle, current status of clinical research, advantages and disadvantages of IoC2, and to make a simple comparison with other analgesic monitoring, so as to provide a reliable basis for the clinical application of IoC2.