Cough
Cough is a reflex explosive expiration that prevents aspiration and promotes the removal of secretions and foreign particles from the lung.
History
Onset and duration
The onset of a cough may be acute or chronic (usually defined as a cough that has persisted for more than three weeks). Sudden onset of an unrelenting bout of violent coughing may be due to an inhaled foreign body. If this is large enough to occlude the airway, coughing abruptly ceases and is supervened by cyanosis and eventually unconsciousness.
Sputum
The frequency, quantity and appearance of expectorated sputum can be very helpful in the differential diagnosis. Cough continuously productive of purulent sputum is suggestive of chronic bronchitis and bronchiectasis. Expectorated bloodstained sputum tends to be a complaint of patients with bronchogenic carcinoma, pulmonary embolism and TB.