Randomized single-center trial evaluating whether bronchoscopic instillation of levofloxacin or gentamicin improves outcomes compared to a sham bronchoscopic procedure in adult ICU patients with non-cystic fibrosis bronchiectasis requiring invasive mechanical ventilation. The primary outcome is a ranked composite of in-hospital mortality and time to ventilator liberation. Safety and procedural adverse events are closely monitored.

Bronchiectasis is a chronic suppurative and inflammatory lung disease of diverse etiology characterized by pathological and irreversible dilatation of the bronchial tree. The impairment of the mucociliary clearance, which results from chronic airway inflammation, may cause long-term colonization or recurrent infection of bacteria, especially Pseudomonas aeruginosa (PA), while bacterial colonization and recurrent infection can aggravate airway inflammation. Sputum retention caused by the impairment of mucociliary clearance can result in mucous plugs, which in turn contribute to airflow obstruction and dyspnea.

Clinically, the major manifestations of bronchiectasis include chronic cough with purulent sputum, dyspnea, and fatigue, which can significantly diminish patients' quality of life. The frequency of exacerbations and decline in lung function may lead to a poor prognosis and a decrease in quality of life.

The purpose of bronchiectasis management is to reduce exacerbations, prevent complications, and improve the quality of life. Long-term instillation of antibiotics and steroids can reduce the concentration of bacteria in the airways, decrease sputum production, attenuate lung function decline, and reduce acute pulmonary exacerbations without nephrotoxicity or ototoxicity. Dexamethasone is one of the most common glucocorticoids that can inhibit the expression levels of inflammatory factors in the airway and reduce the secretion of airway mucus. Topical administration could also reduce the systemic side effects.

Inclusion Criteria:

• patients with bronchiectasis confirmed by high-resolution CT chest(HRCT)
• patients with acute exacerbation of bronchiectasis who need antibiotic treatment at the hospital due to exacerbation
• mechanically ventilated patients in the respiratory ICU
• Age more than or equal to 18 years

Exclusion Criteria:

• patients with active pulmonary tuberculosis
• patients with allergic bronchopulmonary aspergillosis
• patients who underwent interventional bronchoscopy for hemoptysis
• age less than 18 years

All participant data will be recorded using a unique, study-specific Participant Identification (PID) number. This PID is not derived from any personal information and will be used for all data collection, analysis, and future data sharing. All datasets intended for sharing or publication will be thoroughly de-identified, with no direct or indirect personal identifiers included.

Results from this trial will be published in two main peer-reviewed manuscripts: one reporting outcomes from the acute hospitalization phase (primary analysis), and a second reporting on long-term, 1-year follow-up outcomes. Both publications will use only de-identified PID-linked data and will cite the same ClinicalTrials.gov registration number.

Beginning 12 months after publication of the primary (acute phase) results, for a period of 3 years.

Data from both the acute hospital phase and the 1-year follow-up phase will be available after publication of the respective results in peer-reviewed journals.

De-identified individual participant data (IPD) will be made available to qualified researchers following publication of the primary and long-term results. Access will be granted for methodologically sound proposals that are consistent with the approved protocol and ethical standards. All requests must include a clear scientific rationale, analysis plan, and evidence of appropriate institutional review board (IRB) approval or waiver.

Data will be shared under a data use agreement, which ensures:

No attempt to re-identify participants, Use of data only for the approved research purpose, Compliance with all applicable privacy and security regulations. Requests will be reviewed by the trial's Steering Committee and Data Access Committee. Approved researchers will receive de-identified, PID-linked datasets and supporting documentation.

To request data access, interested parties should contact the Principal Investigator.

Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor) All participants, clinical care providers (including bedside staff), investigators, and outcomes assessors will be blinded to group allocation. The use of a sham bronchoscopic procedure in the control arm ensures that all patients undergo a procedure of similar appearance and duration, minimizing the risk of performance and detection bias. Unblinding will only occur in the event of medically necessary interventions during the sham procedure, which will be documented as protocol deviations while maintaining the intention-to-treat analysis.