Cranial electrotherapy stimulation (CES) is a non-invasive and safe intervention, transmitting microcurrents of brain stimulation and releasing various neurotransmitters such as endorphin and downstream hormones to modulate autonomic nervous system, as a result, for treating anxiety, depression, insomnia, and pain.~Acute postoperative pain annoys patients receiving surgery. Once acute postoperative pain is poorly controlled, it may result in adverse acute effects (i.e., physiologic and psychologic stress), chronic effects (i.e., delayed long-term recovery and chronic pain), and, in consequence, excess length of hospitalization and extra costs. Besides, inflammatory reactions mediated by immune system are formed after tissue injury (e.g. trauma, surgery, etc), release serial inflammatory cytokines and are related to pain signal transmission. However, clinical studies and applications of CES focus on management of chronic pain, modulation of mood and insomnia rather than acute postoperative pain in recent years.~The investigators investigate a double-blind, randomized controlled trial to figure out if intraoperative CES could decrease dosage of intraoperative anesthetics and patient-controlled analgesia (PCA) consumption in patients undergoing colon cancer surgery. The investigators also collect blood samples before and after surgery for analysis of serum cytokines. Meanwhile, Bispectral IndexTM (BISTM) monitoring and Analgesia Nociception Index (ANI) are prescribed during the surgery not only for measuring of the effects of anesthetics and sedatives on the brain, but also evaluating perioperative analgesia. Thereby, the effectiveness of CES for management of acute postoperative pain may introduce clinicians for alternative application of pain control after surgery in the future.
Cranial electrotherapy stimulation (CES) is a non-invasive intervention to treat anxiety, depression, insomnia, and pain. But clinical studies and applications of CES in relation to acute postoperative pain are few. tThe investigators investigate a double-blind, randomized controlled trial to figure out if intraoperative CES could decrease dosage of intraoperative anesthetics and patient-controlled analgesia (PCA) consumption in patients undergoing colon cancer surgery.