Cough is an explosive expiration that provides a normal protective mechanism for clearing the tracheobronchial tree of secretions and foreign material.
When excessive or bothersome, it is also one of the most common symptoms for which patients seek medical attention.
· Coughing may be initiated either voluntarily or reflexively.
· As a defensive reflex, it has both afferent and efferent pathways.
· The afferent limb includes receptors within the sensory distribution of the trigeminal, Glossopharyngeal, superior laryngeal, and vagus nerves.
· The efferent limb includes the recurrent laryngeal nerve and the spinal nerves.
· Cough can be initiated by a variety of irritant triggers either from an exogenous source (smoke, dust, fumes, foreign bodies) or from an endogenous origin (upper airway secretions, gastric contents.
· Any disorder resulting in inflammation, constriction, infiltration, or compression of airways can be associated with cough.
· A neoplasm infiltrating the airway wall – bronchogenic carcinoma.
· Airway infiltration with granulomas – tuberculosis.
· Compression of airways results from extrinsic masses such as lymph nodes or mediastinal tumors, or rarely from an aortic aneurysm.
· Parenchymal lung disease – pneumonia, and lung abscess.
· Congestive heart failure may be associated with cough, probably because of interstitial as well as peribronchial edema.
Types based on duration
· Acute cough (< 3 weeks) due to upper respiratory infection, pneumonia, pulmonary embolus, and congestive heart failure
· Sub-acute cough (between 3 and 8 weeks) is commonly post-infectious, resulting from persistent airway inflammation and/or postnasal drip following viral infection.
· Chronic cough (>8 weeks) COPD, bronchogenic carcinoma, asthma, and gastro esophageal reflux.
· Determining the underlying cause
· Elimination of irritants (cigarette smoke, ACE inhibitors)
· Bronchodilators for potentially reversible airflow obstruction, inhaled Glucocorticoids for eosinophilic bronchitis.
· Chest physiotherapy and other methods to enhance clearance of secretions in patients with bronchiectasis.
· Antihistamine-decongestant combination,
· Antitussive agent, which increases the latency or threshold of the cough center (codeine)- dry cough.