A cough is a forced exhalation through the mouth with characteristic sounds. It is often preceded by a feeling of farting or scratching in the throat, tightness in the chest. In most cases, the act of coughing is accompanied by chest pain. The cough may end with the secretion of yellow-green, “rusty”, vitreous and other varieties of sputum, typical for certain diseases. With prolonged cough attack sometimes reflexive vomiting, blue nasolabial triangle due to hypoxia are possible.
More often, the cough occurs against a background of other symptoms of the respiratory system: pain in the throat, chest, nasal congestion. When the vocal apparatus is involved, the symptom is combined with hoarseness of the voice up to aphonia. In severe diseases, coughing jolts may follow one after another without a break, which is called cough reprise. If a patient has a persistent cough, especially with purulent or bloody sputum and general disturbances, this is a direct indication for a visit to a pulmonologist.
The act of coughing is a complex reflex defense mechanism that is necessary to clear foreign bodies, toxins, and excess mucus from the airways. The cough reflex begins at irritant receptors in the larynx and tracheobronchial tree, which are innervated by fibers of the vagus nerve. The most sensitive to external influences are the vocal cords, the epiglottis, and the zone of bifurcation of the trachea into the bronchi. Receptors respond to ingestion of mucus, chemicals, contaminants, and large foreign bodies.
Excitation from the irritant nerve endings is directed to the cough center, located in the medulla oblongata, and to neurons of the reticular formation. These structures are responsible for the coordinated work of all muscle groups involved in the act of coughing. The first phase of the reflex includes a deep short breath lasting about 2-3 s, which is accompanied by spasm of muscles of larynx and vocal slit, increase of tone of bronchial musculature. Intrathoracic pressure can reach 140 mm Hg.
This is followed by sharp contraction of abdominal muscles, diaphragm to overcome increased resistance with rapid exhalation through the mouth. Airflow rate during coughing reaches 50-120 m/s, which is 25-30 times higher than during quiet breathing. Together with a stream of air, droplets of mucus, dust, foreign particles are removed from the bronchopulmonary system. A single coughing act ends with a forced exhalation, but with excessive irritation of the receptors the reflex can be repeated many times.
In the lung parenchyma itself there are no sensitive nerve endings, so in primary lung lesions the cough indicates the progression of the disease, involvement in the pathological process of the bronchi or pleura. The cough reflex can also form with cardiac pathology, which contributes to increased pressure in the pulmonary vascular system. This leads to the release of the liquid part of the blood into the alveoli and interstitial tissue, which ends in irritation of the receptors, an intense cough, intensifying in a horizontal position.
Cough is not a specific sign of any disease, but its diagnostic value increases when specific features of the symptom are identified. Classification is based on the presence or absence of sputum, timbre, frequency, duration, and frequency of occurrence during the day. The most common and important for diagnosis is the allocation of varieties of the coughing act depending on the presence of secretion:
Dry cough. It is not accompanied by secretion from the airways. The appearance of the symptom is observed in the initial stage of bronchitis, pneumonia, when the inflammatory process is localized in the larynx or trachea. The attack may occur when the pleura is affected, the mediastinum, compression of the airways by volumetric formations, fibrosing processes in the lungs.
Moist cough. Always ends with sputum, which may be of varying color, viscosity, and odor. Purulent sputum is more typical for inflammatory diseases of the airways, “vitreous” – for an attack of bronchial asthma. The presence of streaks of blood can indicate neoplasms in the lungs, pathology of the cardiovascular system.
There is a classification according to loudness and timbre, there is a “barking” cough, characteristic of laryngitis, false croup in children, deaf weakened in chronic obstructive bronchitis, silent, indicating the destruction of the vocal cords. In a separate category are allocated bitonal cough, in which sounds an additional high tone, most often indicating the development of tumorous bronchoadenitis in childhood.
In diagnostic terms, it is important to classify the symptom according to the time of manifestation: morning cough is more often identified in smokers and asthmatics, night attacks are pathognomonic for tuberculosis and cardiac asthma. In inflammation of the respiratory tract there is no association of the symptom with the time of day. According to the mechanism of formation of the symptom, a central (neurotic) cough is associated with direct excitation of reflex zones in the brain at neurosis, and reflex cough, caused by irritation of nerve endings of the respiratory organs, upper sections of the esophagus.
Causes of superficial cough
The symptom occurs in healthy people when they inhale polluted polluted air, pungent smells. Usually coughing is associated with damage to the upper airways. There are the following causes of coughs:
Acute respiratory infections: influenza, adenovirus infection.
Lesions of ENT organs: chronic tonsillitis, bacterial pharyngitis and rhinopharyngitis, postnasal drip syndrome.
Pediatric infections: the initial period of measles and rubella, paracocclusis.
Foreign bodies of the respiratory tract.
Complications of pharmacotherapy: receiving hypotensive drugs (ACE inhibitors, beta-blockers), antiarrhythmic drugs.
Rare causes: pharyngeal neurosis, thyroid cancer.
Causes of deep dry cough
Intense cough paroxysms without sputum secretion are most characteristic of the localization of the pathological process in the lower respiratory tract. The symptom may be combined with chest pain, shortness of breath. An attack of dry deep cough is provoked by the following reasons:
Inflammatory processes in the respiratory organs: laryngotracheitis, bronchitis, whooping cough.
Tuberculosis: pulmonary form, acute disseminated variant, lesion of mediastinal lymph nodes.
Non-inflammatory bronchial diseases: Williams-Campbell syndrome, bronchial foreign body, bronchoobstructive syndrome.
Lung diseases: pneumosclerosis, acute atelectasis, malignant tumors.
Causes on the side of the pleura: benign and malignant tumors, pleurisy, pneumothorax.
Allergic pathology: bronchial asthma, alveolitis, asthmatic bronchitis.
Diseases of other organs: esophageal diverticula, dilated cardiomyopathy, pericarditis.
Occupational diseases: berylliosis, silicosis, silicatosis.
Causes of wet cough
Normally, after coughing, a person separates a negligible amount of transparent mucus, but more often the wet cough is caused by respiratory disease. Usually after coughing up sputum, the patient feels relief. Common causes of cough with sputum:
Bronchitis: purulent (including its complication – bronchiectatic disease), obstructive, atrophic.
Pulmonary pathology: viral and bacterial pneumonias, hemosiderosis, echinococcosis.
Inflammation of the larynx and trachea.
Pulmonary edema: in complications of acute heart failure, cardiac asthma, severe lesions of the respiratory system.
Tumors: bronchioloalveolar cancer, bronchial carcinoid, squamous cell cancer.
Causes of barking cough
Cough paroxysms with a characteristic loud (“barking”) sound are observed when the pathological process spreads to the mucous membrane of the larynx and the area of the vocal cords. The development of a barking cough is most often caused by:
Lesions of the larynx: laryngitis, true croup in diphtheria, false croup.
Respiratory tract infections: whooping cough, parainfluenza, adenoviral pharyngitis.
Tracheal diseases: complications after intubation, dyskinesia, stenosis.
Allergic diseases: bronchial asthma, allergic laryngitis.
Rare causes: berylliosis, exudative pericarditis, bronchial tuberculosis.
The most common causes of cough are diseases of the respiratory system, so a pulmonologist is responsible for organizing the examination. To make a diagnosis it is necessary to use a set of instrumental methods and laboratory tests, which are aimed at detecting morphofunctional disorders and signs of pathological processes. The greatest diagnostic value are:
Examination of the ENT organs. Rhinoscopy, pharyngoscopy and laryngoscopy are prescribed to visualize the mucosa of the upper respiratory system. During the search for the cause of the symptom, attention is paid to inflammatory tissue changes, volumetric formations the nature and amount of sputum on the walls of the organs. A swab is taken from the pharynx for bacterioscopy.
Sputum analysis. Microscopic and bacteriological examination of the discharge helps establish the etiology of the disease. With prolonged dry cough it is necessary to exclude infection with Koch’s bacillus, for which sputum culture on special nutrient media is carried out. If necessary, the study is supplemented by express methods of detecting tuberculosis.
Radiological methods. Radiography is recognized as the “gold standard” for the diagnosis of pneumonia as the main cause of cough. X-rays are informative when bronchial involvement and mediastinal structures are affected, which are often accompanied by cough. X-rays are performed in two projections. Computed tomography is indicated for a detailed study of thoracic cavity structures.
Serologic reactions. Determination of blood antibodies to various viral and bacterial pathogens is necessary to verify the diagnosis. Modern laboratory methods are used – ELISA, RIF, PCR. Additionally, blood chemistry is performed to detect signs of acute inflammation, and changes in immunogram are indicated, if allergy is suspected.
Other instrumental methods. To visualize the structures of the bronchial tree, bronchoscopy is prescribed, during which biopsy of pathologically changed areas for cytomorphological analysis is possible. Contrast bronchography under local anesthesia is recommended for possible tumor neoplasms.
When respiratory causes of cough are excluded, additional diagnostic methods are used: contrast radiography of the esophagus, ECG, and ultrasound of the heart. To determine the degree of respiratory disorders, blood gas composition is determined. Spirography with estimation of basic indexes – volume of forced expiratory volume, vital capacity of lungs are performed for respiratory disorders. Some patients need consultation with immunologist-allergologist.
Help before diagnosis
To reduce the frequency of coughing episodes, patients are advised to avoid strong odors, sudden changes in air temperature, limit consumption of spicy foods and carbonated beverages. Plenty of warm drinking is recommended: teas, herbal kits, compotes from dried fruits. Gargling of the throat with antiseptic solutions and inhalation are used to cleanse the airways and stimulate phlegm production. Persistent cough, which lasts more than 2-3 days, accompanied by chest pain or shortness of breath, is an indication to seek medical attention and establish its cause.
Medical tactics depends on the underlying disease, the intensity and duration of cough paroxysms. With superficial coughing, soothing inhalations and gargles are sufficient, deep dry or wet cough requires the use of specific drug therapy. Treatment is supplemented by physical therapy methods, chest massage to facilitate expectoration of sputum. Taking into account the leading cause of cough, the doctor prescribes different groups of medications:
Mucolytics. Means liquefy sputum, improve its discharge during coughing episodes. Drugs provide sanation of the bronchial tree and accelerate recovery. As a rule, they are combined with expectorants for mutual enhancement of pharmacological effects.
Antibiotics. Drugs with antibacterial action are taken with purulent inflammatory processes in the bronchial tree and lungs. The most effective are considered beta-lactams, macrolides. In severe acute respiratory infections, antiviral agents are needed.
Antituberculosis drugs. To treat tuberculosis, there are separate drug regimens that include at least 3 drugs. Vitamins and immunomodulators are prescribed to reduce side effects.
Bronchodilators. Beta-adrenomimetics, theophylline are indicated for cough paroxysms that are caused by reversible or irreversible bronchial constriction. In severe obstruction, glucocorticosteroids are administered by inhalation.
Anti-allergic. The most commonly used drugs are drugs from the group of H1-histamine receptor blockers, mast cell membrane stabilizers, and leukotriene inhibitors. In severe bronchial asthma, hormonal agents are used.
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