Pathophysiology
Clinical meaning
The respiratory tract is lined with ciliated pseudostratified columnar epithelium containing goblet cells that produce mucus. This mucociliary escalator is the primary defense mechanism for trapping and clearing inhaled particles, pathogens, and debris from the airways. Mucus is produced at approximately 100 mL per day in healthy adults, with the consistency and volume regulated by hydration status, autonomic nervous system input, and inflammatory mediators. When disease, injury, sedation, or neuromuscular weakness impair the cough reflex or mucociliary clearance, secretions accumulate in the tracheobronchial tree. Retained secretions increase airway resistance, reduce alveolar ventilation, promote bacterial colonization, and can lead to atelectasis, pneumonia, and respiratory failure. Airway suctioning is a sterile or clean invasive procedure that uses negative pressure to mechanically remove secretions from the oropharynx, nasopharynx, or trachea when the patient cannot clear them independently. The procedure stimulates the vagus nerve (cranial nerve X), which innervates the heart and airways. Vagal stimulation during suctioning can cause bradycardia, hypotension, bronchospasm, and laryngospasm. The practical nurse must understand that suctioning itself carries risks including hypoxemia (removal of oxygen along with secretions), mucosal trauma...