The most common cause of cough – smoking. In non-smokers, in 93,6% of cases, the cause of cough is three pathological conditions: postnasal drip syndrome, bronchial asthma, gastroesophageal reflux disease. The most common cause of acute cough is ARVI. It may also result from aspiration or inhalation of irritants. When a cough occurs, both the patient and the doctor assume, first of all, a disease of the respiratory system, bronchopulmonary apparatus. However, cough can be a manifestation of pathology of other organs and systems – circulatory and digestive, ENT organs, etc. In total, there are about 50 causes of cough, which can be (conditionally) divided into groups.
- Inhalation of irritating substances (smoke, dust, gas);
- Aspiration of a foreign body, discharge from the upper respiratory tract (with sinusitis or rhinitis, discharge from the nose flows down the back wall of the pharynx – postnasal drip syndrome) or stomach contents (with gastroesophageal reflux disease).
- Inflammation of the respiratory tract.
Infectious causes of cough:
- ARVI:
- laryngitis, pharyngitis (may be of non-infectious origin), chronic tonsillitis;
- acute and chronic bronchitis (after acute bronchitis, a cough may persist for several weeks due to increased sensitivity of the bronchi);
- pneumonia:
- lung abscess;
- bronchiectasis;
- pleurisy;
- whooping cough (can cause prolonged coughing in both children and adults).
Allergic causes of cough:
- bronchial asthma:
- “eosinophilic” bronchitis; allergic rhinosinusitis.
Airway infiltration:
- for lung cancer:
- in carcinoids;
- in sarcoidosis:
- with tuberculosis.
Compression of the trachea and bronchi by enlarged lymph nodes, mediastinal tumor or aortic aneurysm, laryngeal cancer, goiter, strumectomy.
Interstitial, parenchymal lung diseases (histiocytosis X, cryptogenic fibrosing alveolitis, etc.), pathology of the trachea and bronchi (tracheobronchial dyskinesia), diffuse connective tissue diseases (Sjogren’s syndrome, etc.).
Cardiovascular causes of cough:
- heart failure (peribronchial and interstitial edema);
- aortic aneurysm:
- pulmonary embolism;
- heart defects;
- pericarditis.
Use of medications (taking ACE inhibitors, oxygen therapy, inhalation of powder dosage forms, “amiodoron lung”),
Psychogenic causes of cough.
Reflex causes of cough:
- with pathology of the external auditory canal (cerumen plugs), middle ear canal, etc.;
- with a long uvula;
- with gastroesophageal reflux disease (reflex as a result of stimulation of the vagus nerve receptors in the distal part of the esophagus);
- with hyperventilation syndrome.
Mechanism of cough development
Coughing as a protective reflex aimed at clearing the airways occurs with mechanical coughing. Chemical, thermal irritation of cough receptors or with the development of an inflammatory process. The reflex arc consists of five components:
- Cough receptors.
- Afferent nerves.
- Medullary cough center.
- Efferent nerves.
- Effectors (respiratory muscles).
The cough reflex can be caused by stimulation of receptors in the oral cavity, paranasal sinuses, larynx (especially the interarytenoid space), vocal cords, pharynx, external auditory canal and auditory tube, trachea and its bifurcation, bronchial division zones, pleural receptors, pericardium, diaphragm, distal part esophagus and stomach. In this case, the speed of the created air flow is not much lower than the speed of sound. It is necessary to clarify that not all foreign bodies inhaled with air are removed by coughing; a significant amount of dust particles, as well as mucus formed in moderate quantities, are removed from the lumen of the bronchi by the ciliated epithelium.
Prolonged or regularly recurring cough, as a rule, reflects a pathological process. A high correlation has been proven between the degree of inflammation of the bronchial tree and the sensitivity of cough receptors. Women have a lower cough threshold, i.e. cough, with the same provocation, occurs more quickly in women than in men. The cough reflex is under the control of the cerebral cortex and can be suppressed to a certain extent. Like any other unconditioned reflex, coughing does not always serve to protect the respiratory tract. In some cases, it represents a manifestation of a pathological process without any positive results.