This prospective randomized controlled study will compare the effects of sevoflurane and desflurane on the Analgesia Nociception Index (ANI) in adult patients undergoing general anesthesia. Participants will be randomized to maintenance anesthesia with either sevoflurane or desflurane, and ANI responses to a standardized nociceptive stimulus will be measured under equi-minimum alveolar concentration (age-adjusted 1.0 MAC) conditions. The primary objective is to compare the change in ANI before and after tetanic stimulation between the two anesthetic groups. Secondary measurements will include bispectral index, blood pressure, heart rate, and end-tidal anesthetic concentration around the time of stimulation.
Adults aged 19 to 79 years
Patients undergoing general anesthesia
American Society of Anesthesiologists (ASA) physical status I or II
History of taking medications that may affect the central nervous system or autonomic nervous system (e.g., anticholinergics, beta-blockers, antidepressants, anxiolytics, hypnotics, or analgesics)
Known hypersensitivity to sevoflurane, desflurane, or other halogenated anesthetics, or a personal or family history of malignant hyperthermia
Neurologic or psychiatric disorders (e.g., depression, dementia, or cerebral infarction)
Arrhythmia