The Effect of IoC on Analgesia for Elderly Patients With Postoperative Effectiveness

The morbidity of colorectal cancer and the surgery number among elderly is growing. The investigators need to provide more advanced and specific monitoring technology for these patients. Index of consciousness (IoC) monitor is now widely used among endoscopy, cholecystectomy and other common clinical applications. The investigators goal is to verify whether using IoC monitor could help to improve the postoperative recovery after colorectal surgery.