The objective of our project is to find procedures and/or parameters to predict the diagnostic recovery (≥ 60% of the administered fluid volume) of bronchoalveolar lavage (BAL) fluid before bronchoscopy and to assess the impact of using non-invasive mechanical ventilation (NMV) or continuous positive airway pressure (CPAP) to achieve diagnostic recovery in patients with chronic obstructive pulmonary disease (COPD) and interstinal lungs disease for whom BAL performed during ordinary bronchoscopy turns out to be non-diagnostic.

Inclusion Criteria:

1. Patients with diagnosed stable COPD (Stages 1-3) - experimental group; Patients with interstitial lung disease - experimental group
2. Former and current smokers with normal lung function - potential control group 1;
3. Never-smokers with normal lung ventilation - potential control group 2.

Exclusion Criteria:

1. No written, informed consent to participate in the research project.
2. Severe respiratory failure (SaO2 < 90%)
3. The patient qualified for home oxygen treatment or home mechanical ventilation
4. Severe heart failure (NYHA class IV)
5. COPD mMRC IV
6. Myocardial infarction in the last two weeks or unstable angina
7. Severe, particularly ventricular arrhythmias
8. Platelet count < 20,000/ul
9. INR > 2 or APPT > 36 sec
10. Very severe obstruction: forced expiratory volume in 1 second (FEV1) < 30% of predicted.