Effects of Surgery on Airway Mechanics in Tracheal Stenosis

Abstract

12 patients suffering from severe extrathoracic tracheal stenosis mainly caused by long-term artificial ventilation were investigated by comparing their airway mechanics before and after tracheal sleeve resection and during long-term follow up. The investigations included body plethysmography, flow-volume relation, effect of bronchodilator, bronchial challenge and endoscopic estimation of the tracheal diameter. Tracheal sleeve resection in stenosis doubles the tracheal diameter from 5.9 to 11.0 mm. Resistance parameters and forced expiratory flow values reflected the significant improvement best. Airway structure remains stable during long-term follow-up, and effort-dependent parameters improve further. Compared to normal volunteers with artificially induced stenosis patients show a higher tolerability for airway narrowing. A tracheal diameter of 5 mm produces severe complaints and distinct functional distortions which are shown in specific airway resistance of 7.5 cm H₂O^-1•s, specific airway conductance of 0.02 cm H₂O•s^-1 and FEV₁ of 1 l•s^-1. These values are absolute indications for resection. Tracheal stenosis after long-term artificial respiration can be influenced slightly by bronchodilator therapy. Nonspecific bronchial hyperreactivity is present, suggesting increased reagibility of the bronchial smooth muscles.