Bronchoalveolar Lavage and Tracheal Aspirate for Assessing Airway Inflammation in Children

Studies using bronchoalveolar lavage (BAL) and tracheal aspirate (TA) have increased our knowledge of the underlying airway inflammation present in the childhood disorders of asthma, cystic fibrosis (CF), and neonatal chronic lung disease (CLD) (1–6). A BAL sample is obtained by wedging a bronchoscope or catheter into a bronchus and isolating the distal airway. A volume of saline is instilled and the fluid aspirated back from the airway, using gentle suction. The aim of this process is to obtain aspirated fluid that will contain the microbes, cells, and noncellular constituents present in the epithelial lining fluid of the small airways and alveoli. Flexible fiberoptic bronchoscopy (FOB) allows a visual location and wedging of the bronchoscope tip (1, 7–12). In blind nonbronchoscopic BAL, a catheter is passed through an endotracheal tube and blindly wedged in a distal airway. This technique has been used to obtain normal cellular and noncellular constituents and to study diffuse airway inflammation (13–16). In neonatal studies, a TA or bronchial washing can be obtained by inserting a catheter through an endotracheal tube for a short distance (usually not wedged) and aspirating back mucus or instilled fluid. Darlow and coworkers (17) have shown that samples obtained by dry shallow suctioning, often used routinely to maintain airway patency in neonatal intensive care, may also provide adequate samples for research purposes. The mean values of dry and lavage samples were similar with respect to myeloperoxidase and a 1 -antitrypsin content.