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.

This is a multicenter clinical study. Study Objective: To explore the reasonable range of the qNOX and the optimal timing for gastroscopy and colonoscopy during intravenous sedation-assisted endoscopic examinations. Study Protocol: A total of 900 patients undergoing intravenous sedation-assisted digestive endoscopy in the outpatient clinics of the participating institutions were selected. Among them, 450 patients undergoing gastroscopy were divided into a propofol group (GP group) and a propofol combined with low-dose sufentanil group (GSP group); 450 patients undergoing colonoscopy were divided into a propofol group (CP group) and a propofol combined with low-dose sufentanil group (CSP group). The bispectral index monitor (Apollo-9000A) was used to monitor the qCON and qNOX of patients during intravenous sedation-assisted digestive endoscopy. The values of qCON, qNOX, SBP (systolic blood pressure), DBP (diastolic blood pressure), MAP (mean arterial pressure), HR (heart rate), SpO2 (peripheral capillary oxygen saturation), and MOAA/S (Modified Observer's Assessment of Alertness/Sedation) scores at different time points during gastroscopy and colonoscopy were observed and recorded. The occurrence of adverse events during and after the examinations was also documented.

Inclusion Criteria

1. Age between 18 and 60 years old;
2. ASA-PS (American Society of Anesthesiologists Physical Status) classification of I to II;
3. Body Mass Index (BMI): 18 to 28 kg/m²;
4. Patients undergoing diagnostic and therapeutic procedures under sedation for lower gastrointestinal endoscopy;
5. Clear understanding and voluntary participation in this study, with informed consent signed.

Exclusion Criteria

1. Patients requiring complex endoscopic techniques for diagnosis and treatment;
2. Patients who have participated in other clinical trials in the past three months;
3. Pregnant and lactating patients;
4. Patients with allergies to sedatives/anesthetics and other severe anesthesia risks;
5. Patients with preoperative chronic pain or a history of substance abuse;
6. Patients with severe neurological diseases such as stroke, hemiplegia, convulsions, epilepsy, etc.;
7. Patients with known difficult airways such as limited mouth opening, restricted neck and jaw movement, rheumatoid spondylitis, temporomandibular joint arthritis, etc.;
8. Patients with potentially life-threatening circulatory and respiratory diseases that are not adequately controlled, such as uncontrolled severe hypertension, severe arrhythmias, unstable angina pectoris, acute respiratory infections, asthma exacerbations, etc.;
9. Patients with liver dysfunction (Child-Pugh Class C or higher), acute upper gastrointestinal bleeding with shock, severe anemia, gastrointestinal obstruction with gastric retention.