The compliance and expiratory resistance of the tracheobronchial tree is increased in infants with tracheobronchomalacia because of a weakness in cartilaginous support of the airway. Life threatening episodes may occur in these patients due to airway collapse. The goals of this study were to compare the effects on respiratory system mechanics of stenting the airway with either continuous positive airway pressure (CPAP) or a long tracheostomy tube. Five infants were studied: two had bronchopulmonary dysplasia (BPD), 2 had associated congenital anomalies, and one had tracheomalacia and polydactyly; none had a tracheoesophageal fistula. All patients required tracheostomy and were treated with CPAP. Lung mechanics were evaluated by measuring transpulmonary pressure, obtained by subtracting airway opening pressure from pleural pressure measured with an esophageal balloon, and flow measured with a pneumotachometer placed in series with the tracheostomy. Dynamic compliance (Cdyn) and total respiratory system resistance (Rt) were calculated by two-factor, least-mean-squares analysis, solving for the equation of motion of the lung with the PeDS system (MAS, Hatfield). In all subjects Cdyn increased and Rt decreased with increasing CPAP. In 4 subjects the airway was stented with a specially designed, long tracheostomy tube which reached to just above the carina; the special tube improved dynamic mechanics sufficiently to permit the discontinuation of CPAP. Speech was improved by fenestrating the tube and the use of a one-way inspiratory valve, placed over the tracheostomy. Inspiration occurred via the tracheostomy and expiration was directed to the larynx.