Intraoperative nociception monitoring

Kang, Hoon

Abstract

Monitoring depth of anesthesia has been an aim of anesthesia for several decades. Monitoring of clinical parameters, such as cardiovascular signs, sweating, tearing and pupil signs has been routinely used. Many attempts have been made to develop systems for the accurate assessment of anesthetic depth. There have been some products available for monitoring hypnosis and sedation, and some partially acceptable measures for nociception monitoring have become available. Most of them are based on cerebral function monitoring (electroencephalogram) and autonomic responses. Awareness, with or without recall, is due to inadequate hypnosis, inadequate analgesia or increased levels of surgical stimulation at any stage during anesthesia. The ability to distinguish consciousness from unconsciousness and to detect nociception for a variety of anesthetic agents at equipotent doses is an essential element of a monitor and clinical end-point. Given the best sign of awareness is considered patient movement for any reason, neuromuscular blockade makes the assessment of depth of anesthesia difficult. While a reliable monitor ensuring unconsciousness and painlessness is required, several systems have been investigated. Although the intraoperative anesthetic state results from the balance between the effects of surgical stimulation and the effects of anesthetic agents on the central nervous system, it remains unclear if any of the current methods for monitoring anesthetic adequacy completely reflects this balance.