Index of consciousness (IoC) consisting of IoC1 and IoC2, is a new analgesia monitoring indicator in anesthesia evaluation in the laparoscopic radical resection of colorectal cancer. Although the precise anesthetic dosage adjusted by IoC1 has been confirmed to enhance the recovery and reduce the complications of anesthesia, the most appropriate range of IoC2 during anesthesia remains unclear. To investigate the correlation between IoC2 and peri-operative indicators of patients during laparoscopic radical resection of colorectal cancer, the current randomized, controlled, and single-blinded clinical trial was performed. Participants were divided randomly into three groups with different anesthesia depth monitored by IoC2 during their laparoscopic radical resections. Primary outcomes included the dosage of remifentanil. Secondary outcomes included other physiological indexes and complications. The remifentanil dosage and the awakening time increased as IoC2 decreased. The incidences of hypotension and hypoxemia decreased with the elevated IoC2, but the risk of intra-operative awareness also increased. The impact caused by anesthesia to the immune system and health-related life quality of the patients descended with reduced anesthetic level. The IoC2 range of 35–45 could represent the most appropriate anesthetic depth during laparoscopic radical resection, which provides a new perspective for the clinical treatment of colon cancer.

由IoC1和IoC2组成的意识指数（IoC）是大肠癌腹腔镜根治性切除术中麻醉评估中的一种新的镇痛监测指标。尽管已确认通过IoC1调节的精确麻醉剂量可提高恢复率并减少麻醉并发症，但仍不清楚麻醉期间IoC2的最合适范围。为了研究大肠癌腹腔镜根治性切除术中IoC2与围手术期指标之间的相关性，目前进行了一项随机，对照和单盲临床试验。参与者被随机分为三组，分别在腹腔镜根治性切除术中通过IoC2监测麻醉深度。主要结局包括瑞芬太尼剂量。次要结果包括其他生理指标和并发症。随着IoC2的降低，瑞芬太尼的剂量和觉醒时间增加。随着IoC2升高，低血压和低氧血症的发生率降低，但术中意识的风险也增加。麻醉对患者免疫系统和健康相关生活质量的影响随着麻醉水平的降低而降低。IoC2范围为35–45可能代表腹腔镜根治性切除术中最合适的麻醉深度，这为结肠癌的临床治疗提供了新的视角。但是术中意识的风险也增加了。麻醉对患者免疫系统和健康相关生活质量的影响随着麻醉水平的降低而降低。IoC2范围为35–45可能代表腹腔镜根治性切除术中最合适的麻醉深度，这为结肠癌的临床治疗提供了新的视角。但是术中意识的风险也增加了。麻醉对患者免疫系统和健康相关生活质量的影响随着麻醉水平的降低而降低。IoC2范围为35–45可能代表腹腔镜根治性切除术中最合适的麻醉深度，这为结肠癌的临床治疗提供了新的视角。