The goal of this clinical trial is to learn whether bedside flexible bronchoscopy-guided airway clearance can improve lung aeration in adult patients who are receiving invasive mechanical ventilation and have atelectasis with a high airway secretion burden.

The main questions it aims to answer are:

Does bedside flexible bronchoscopy-guided airway clearance reduce the proportion of nonaerated lung tissue from baseline to day 5? Does this treatment improve other lung aeration measures, respiratory mechanics, arterial blood gas parameters, pulmonary infection score, ventilator-free days, intensive care unit length of stay, and safety outcomes?

Researchers will compare usual airway care plus bedside flexible bronchoscopy-guided airway clearance with usual airway care alone to see if bronchoscopy-guided airway clearance improves lung aeration and clinical outcomes.

Participants will be randomly assigned to one of two groups. Participants in the usual care group will receive standard airway management, which may include airway suctioning, postural drainage, humidification, chest physiotherapy, and other routine respiratory care. Participants in the bronchoscopy group will receive the same usual care, plus bedside flexible bronchoscopy-guided airway clearance when predefined criteria for high airway secretion burden are met.

Participants will have clinical assessments during the study, including chest imaging, respiratory mechanics measurements, arterial blood gas tests, pulmonary infection score assessment, and safety monitoring. The main assessment will compare quantitative chest computed tomography findings at baseline and day 5 to evaluate changes in nonaerated lung tissue.

Inclusion Criteria:

1. Age 18 years or older
2. Receiving invasive mechanical ventilation for at least 48 hours
3. Presence of atelectasis confirmed by chest computed tomography, chest X-ray, or lung ultrasound
4. High airway secretion burden, defined as requiring airway suctioning at least twice per hour during the previous 8 hours
5. Written informed consent obtained from the participant or legally authorized representative

Exclusion Criteria:

1. Expected duration of artificial airway maintenance less than 5 days
2. Untreated tension pneumothorax Known or suspected aspiration
3. Active intrapulmonary hemorrhage
4. Severe dysfunction of other organs with expected short-term mortality within 7 days or need for palliative care
5. Any other condition judged by the medical team to make the participant unsuitable for the study
6. Informed consent not obtained