[Perioperative Management of Patients Receiving Chronic Opioid Therapy].

Recently in Japan, more patients are receiving chronic opioid therapy for cancer pain or chronic pain, and there is an increasing number of such patients presenting for surgery. The anesthesiologist should be familiar with available opioid formulations as well as the change they induce by their chronic administra- tion, such as physical dependence, opioid tolerance and opioid-induced hyperalgesia. Physical dependence results in withdrawal symptoms when the opioid is abruptly interrupted or when the dosage is markedly reduced in a short period of time. Furthermore, these patients tend to have increased pain and increased opioid requirements postoperatively, most likely due to opioid tolerance and opioid-induced hyperalgesia. Peri- operative management of these patients require knowledge and skills to manage these phenomena.