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Definition of the Complaint
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Cough is one of the most common presenting complaints to pediatricians. Importantly, a cough is not a disease by itself, but rather a manifestation of an underlying pathology. A cough is a protective action, and can be initiated both voluntarily and via stimulation of cough receptors located throughout the respiratory tract (ear, sinuses, upper and lower airway to the level of the terminal bronchioles, pleura, pericardium, and diaphragm). A cough may serve to remove irritating substances, excessive/abnormal secretions, or may be secondary to intrinsic/extrinsic airway compression.
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A cough is divided into four distinct phases: inspiratory, compressive, expiratory, and relaxation. These phases are characterized by deep inspiration, closure of the glottis, contraction of expiratory muscles with glottic opening, and relaxation of intercostal and abdominal muscles. Thus, one can see how selective patients with laryngeal or neuromuscular diseases may have ineffective coughs.
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Classification should initially involve differentiating an acute from a chronic cough. A chronic cough is one which lasts longer than 3 weeks. Furthermore, the clinical description of the cough can often be helpful in suggesting an etiology: staccato (pertussis, chlamydia), barking (croup), grunting (asthma), or honking (psychogenic). Timing of the cough, relationship to daily activities, and age of the patient are important factors in further defining the etiology (Table 4-1).
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Complaint by Cause and Frequency
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Overall, some of the most common causes of chronic cough include viral upper respiratory tract infections and asthma (Table 4-2). Beyond these etiologies, age is very important in creating a differential diagnosis for the patient with a chronic cough (Table 4-3). Causes of cough may also be divided by diagnostic category including infectious, allergic/inflammatory, congenital malformations, irritants, aspiration, psychogenic, and other categories (Table 4-4...