Biomarkers and Respiratory Omics as New CHildren Opportunities - Study of Clinical Outcomes and Predictivity Evaluation

Inclusion Criteria: * Age at the beginning of the study 0-17 years old * Clinical indication and qualification by the attending physician for fiberoptic bronchoscopy under general anesthesia: * Obstruction of the airways: * Suspicion of foreign body aspiration * Persistent stridor * Abnormal result of functional tests of respiratory system - flattening of inspiratory or expiratory curve, presence of restriction (tested vital capacity \<5 percentile) or irreversible obstruction (persistence of Tiffneau index \<5 percentile despite administration of bronchodilators) * Radiological findings located in the course of the larynx, trachea or bronchi * Persistent atelectasis on subsequent radiological examinations * Persistent cough \>4 weeks * Hemoptysis * Suspected laryngomalacia or tracheobronchomalacia * Suspected tracheoesophageal fistula * Persistent dyspnea unresponsive to anti-asthmatic treatment used for min. 2 months, with no other identifiable causes * Radiologically detected mediastinal abnormalities * Suspected presence of a vascular ring * Presence of excessive secretions that are impossible for the patient to expectorate * Fine needle biopsy of cystic lesions * Obtained consent from patient/legal guardian for participation in the study Exclusion Criteria: * Active acute respiratory infection up to 4 weeks before the procedure * Taking antibiotics or systemic glucocorticosteroids up to 4 weeks before the procedure * Patients with very severe comorbidities (congenital immunodeficiencies, genetic disorders, neurological or neuromuscular diseases, cancer, severe congenital heart defects, heart failure, liver failure, inflammatory bowel disease, celiac disease) * Patients with blood clotting disorders * Children with diagnosed respiratory diseases other than asthma and protracted bacterial bronchitis - including interstitial diseases, tuberculosis, inflammation of small and medium-sized blood vessels * Patients for whom \>48 hours have passed between suspicion of foreign body aspiration and interventional bronchoscopy * Children with foreign body aspiration having a foreign body located in the trachea