1. Introduction

    Bullae are air-filled spaces of lung tissue resulting from the destruction of alveolar tissues and consolidation of alveoli into large pockets. They offer low resistance to inspiration and tend to increase in size with positive pressure ventilation. A valvelike mechanism may be present that causes air trapping on expiration. Enlarging bullae compress normal lung tissue and vasculature to the point of causing hypoxemia, polycythemia, and cor pulmonale. Overdistended bullae can rupture and cause pneumothorax or tension pneumothorax with cardiopulmonary collapse, requiring insertion of a chest tube. A chest tube may show a large, continuous air leak, and ventilation may be difficult.