Hypoxemia was defined as an SpO2 of < 90% for any duration. Failure to treat promptly can lead to hypoxemia, which may increase the risks of arrhythmia, nausea and vomiting, and cognitive dysfunction. Studies have shown that body position has a direct impact on respiratory function. In special environments, including outside the operating room where emergency airway management for critically ill and injured patients is needed, or in areas with limited medical resources like remote areas, adopting simple interventions by changing position to maintain patients' respiratory function can be more economical, convenient and safe.

Hypoxemia was defined as an SpO2 of < 90% for any duration. Failure to treat promptly can lead to hypoxemia, which may increase the risks of arrhythmia, nausea and vomiting, and cognitive dysfunction. Studies have shown that body position has a direct impact on respiratory function. In special environments, including outside the operating room where emergency airway management for critically ill and injured patients is needed, or in areas with limited medical resources like remote areas, adopting simple positional interventions to maintain patients' respiratory function can be more economical, convenient and safe. This study aims to conduct a prospective, multicenter, randomized controlled trial to observe the level of patients' oxygen saturation and the occurrence of hypoxemia under different body positions (supine and lateral positions), and its impact on prognosis, providing reliable evidence-based medical evidence for the prevention and treatment of complications in patients requiring airway management.

Inclusion Criteria:

1. Patients with 18 years or older
2. Without obvious cardiovascular or pulmonary dysfunction
3. Scheduled to undergo procedure or surgery with sedation
4. Signed the informed consent form

Exclusion Criteria:

1. Preexisting bradycardia (heart rate <50 beats/min), hypotension (systolic blood pressure < 80mmHg), or hypoxemia (SpO2 < 90%);
2. Requiring supplemental chronic or intermittent oxygen therapy because of preexisting diseases
3. Preexisting diseases which unable to tolerate reduced SpO2 or Partial pressure of carbon dioxide in artery (PaCO2) diseases, such as severe cardiovascular and cerebrovascular diseases, intracranial hypertension or severe lung diseases;
4. Coagulation disorders or a tendency of nose bleeding;
5. Patients whose body position cannot be altered;
6. Participated in other intervention clinical studies in the past 3 months;
7. Other conditions deemed unsuitable for inclusion by the researcher;
8. Patients and guardians refused to participate in this trial.