Clinical meaning
Chest physiotherapy (CPT) encompasses a group of airway clearance techniques designed to mobilize and remove retained pulmonary secretions, improve ventilation, and prevent or treat atelectasis. Understanding the normal mechanisms of mucus clearance and the pathophysiology of conditions that impair these mechanisms is essential for practical nurses who perform and assist with CPT. The respiratory tract is lined with pseudostratified ciliated columnar epithelium from the trachea to the terminal bronchioles. This epithelium contains two critical components of the mucociliary escalator, the body's primary defense mechanism for clearing inhaled particles and pathogens from the airways. Goblet cells and submucosal glands produce mucus, a complex viscoelastic gel composed of water (approximately 95%), glycoproteins called mucins (which give mucus its sticky, gel-like consistency), electrolytes, immunoglobulins (IgA), lysozyme, and lactoferrin. Normal mucus production is approximately 100 mL per day. The mucus layer consists of two phases: the sol layer (a thin, watery layer closest to the epithelial surface in which the cilia beat) and the gel layer (a thicker, more viscous layer on top that traps particles). Ciliated cells have approximately 200 cilia per cell,...