Bronchoscopy is currently widely used for the diagnosis and treatment of various respiratory diseases. However, the operation of bronchoscopy is irritating, causes a strong stress response, and shares the airway with the patient, making the patient highly susceptible to respiratory and cardiovascular risks. Among these risks, hypoxia is the most common adverse event.Different drug regimens can be selected for anesthesia under deep sedation. The combination of analgesic agents can help reduce coughing during bronchoscopy. Therefore, we employ a combination of sedative and analgesic drugs for painless bronchoscopy procedures. Among sedatives, propofol is the most commonly used. However, due to its disadvantages, such as respiratory and circulatory depression, we have introduced a novel approach combining remimazolam for sedation. The aim is to investigate whether this new regimen, compared to traditional propofol-based sedation, can reduce the incidence of hypoxia, minimize circulatory depression, and lead to faster postoperative awakening and recovery. Additionally, we hope to observe fewer adverse events, such as perioperative nausea and vomiting, excessive secretions, dizziness, and chills.

Inclusion Criteria:

• ASA Class Ⅲ - Ⅳ
• Scheduled for elective painless bronchoscopy -

Exclusion Criteria:

• Age < 18 years
• Patients who are uncooperative（e.g. due to mental illness）
• Patients who are on chronic use of opioids, benzodiazepine - class hypnotics, or antidepressants
• Patients with a history of allergy to the anesthetics used
• Patients who are anticipated to have a difficult airway
• Body mass index（BMI）<18.5kg/m² or >30kg/m²
• Preoperative oxygen saturation <92% while breathing room air
• Other：Patients who are deemed by the investigator to be unsuitable for participation in this trial