Etiology Of Chronic Cough

Background: Cough is an important defense mechanism that helps clear excessive secretions and foreign materials from the airways, it also presents as one of the most common symptoms for which adult patients seek medical attention. Cough can so profoundly and adversely affect the quality of patients' lives. The retail sales of cough medicines rose to $750 million in 1999 in USA, Canada and Europe. Each cough involves a complex reflex arc. The reflex begins with stimulation of a receptor in the larynx, trachea, and carina. Afferent impulses from cough receptors travel to the cough center, carried by the glossopharyngeal, trigeminal, and phrenic nerves. The efferent impulses of the cough reflex are transmitted to the respiratory musculature through the phrenic and other spinal motor nerves and to the larynx through the recurrent laryngeal branches of the vagi. Vagal efferents also supply the tracheobronchial tree and mediate bronchial smooth muscle constrictions that are believed to assist the cough effort by narrowing the airways, thereby increasing the velocity of air flow, then cough is present.Chronic cough is defined as the only or main symptom of patients, without hemoptysis, chronic respiratory diseases associated with cough or abnormal X-ray examination of chest, with or without sputum. In the past, the duration of cough was considered more than 3 weeks, but now 8 weeks. The etiology of chronic cough is variable, and more than one pathogenic factor occurs in a number of patients. The most common pathogenic factors are postnasal drip syndrome, cough variant asthma and gastroesophageal reflux disease. With the increasing usage of ACEI, incidence of chronic cough is increasing. With the admission of induced sputum, incidence of chronic cough is 10%-20%.Objective: To detect the pathogenic factors of chronic cough around Ji'...