- Bronchoalveolar lavage (BAL; patients and volunteers) Volunteers and patients will undergo bronchoscopy in which a flexible tube (bronchoscope) with a light and special lens at the tip is inserted through the nose or mouth into the lungs, and the lining of the lung is sampled by washing the airways with small amounts of saline. The procedure is performed by a pulmonologist or critical care specialist, usually as an outpatient.