This study is a prospective, single-center, double-blind, randomized controlled trial designed to evaluate the effect of oliceridine versus sufentanil on the incidence of hypoxemia in adult patients undergoing gastrointestinal endoscopy under deep sedation. The trial will compare the rates of hypoxemia (defined as SpO₂ ≤92%) between the two analgesic regimens when combined with propofol. The primary aim is to determine whether oliceridine can reduce the incidence of hypoxemia compared to sufentanil during endoscopic procedures.

Gastrointestinal endoscopy is frequently performed under deep sedation to minimize patient discomfort caused by mechanical stimulation. Currently, the combination of propofol and short-acting opioids, such as sufentanil, is widely used for its reliable sedation and analgesia. However, opioid-induced respiratory depression (OIRD) remains a notable concern. Unlike traditional opioids, oliceridine is a synthetic μ-opioid receptor agonist that preferentially activates G protein pathways while substantially reducing β-arrestin pathway activation, which may lower the risk of opioid-related adverse events, including respiratory depression.

Previous studies suggest that oliceridine is as effective as morphine for pain control and may be associated with a lower incidence of adverse effects, particularly in elderly or obese surgical patients. Clinical data also suggest a lower risk of respiratory depression with oliceridine compared to traditional opioids, but the incidence of hypoxemia with oliceridine during real-world deep sedation remains unclear.

This study aims to enroll adult patients (aged ≥18 years, ASA I-III) scheduled for elective gastrointestinal endoscopy. Participants will be randomly assigned (1:1) to receive either oliceridine (1 mg for gastroscopy or 1.5 mg for colonoscopy) or sufentanil (5 μg for gastroscopy or 7.5 μg for colonoscopy), both in combination with propofol (1-2 mg/kg). The primary outcome is the incidence of SpO₂ ≤92% from the start of sedation to the end of the procedure.

Inclusion Criteria:

• Male or female patients aged ≥ 18 years.
• Scheduled to undergo elective gastrointestinal endoscopy (gastroscopy or colonoscopy).
• American Society of Anesthesiologists (ASA) physical status I-III.
• No history of severe cardiopulmonary dysfunction or other major systemic disease.

Exclusion Criteria:

• Dementia or any cognitive impairment precluding provision of informed consent.
• Known contraindication to oliceridine.
• Chronic (long-term) opioid use.
• Any other medical or logistic condition that, in the investigator's judgment, makes the participant unsuitable for the study (specify reason).

Both participants and investigators will be blinded to group allocation. Study medications (Oliceridine or Sufentanil) will be prepared in identical syringes by a nurse not involved in patient care or outcome assessment, ensuring that neither patients nor clinicians are aware of the treatment assignment.