Nociception is the encoding and processing of noxious stimulation and is considered an objective indicator for monitoring pain. Currently, a new clinically-applied medical-engineering integrated monitoring device for noxious stimulation response has emerged. Its fundamental principle is based on the monitoring of electroencephalographic (EEG) activity, incorporating two monitoring parameters: the quantitative consciousness (qCON) index and the quantitative nociceptive (qNOX) index. This device enables more precise monitoring of anesthesia depth, quantification of patients' anesthesia analgesia and stress levels, and reliable monitoring of responses to noxious stimulation. During tracheal intubation for general anesthesia, when the qCON value falls within the range of 40 to 60 and the qNOX value is between 30 and 50, it indicates that the patient is in an appropriate state of sedation and analgesia. However, there is currently no universally acknowledged standard for the optimal qNOX reference range during conscious sedation endoscopy. Therefore, this study utilizes the noxious stimulation response index (qNOX) to monitor noxious stimulation during the procedure, aiming to identify the best timing for inserting the endoscope during conscious sedation endoscopy and explore the appropriate range of qNOX for this purpose.