COUGH — the protective complex-reflex act which is characterized by sharp increase of intrathoracic pressure at the expense of the synchronous tension of respiratory and auxiliary muscles at the closed glottis with the subsequent its opening and the tolchkoobrazny forced exhalation at Krom from respiratory tracts actively is removed their contents. Frequent, rather constant or steadily repeating To. is a symptom patol. the process most often connected with a disease of a respiratory organs.
Fiziol, a role To. consists in clarification of respiratory tracts from the substances which got to them from the outside at breath or formed it is endogenous if the peristaltic movements of small bronchial tubes and activity of a ciliate epithelium of large bronchial tubes and a trachea do not provide a necessary drainage. The tussive reflex begins usually with the sensitive terminations of a vagus nerve in respiratory tracts or with receptors of a pleura from which the irritation is transferred to the tussive center about dolgovaty a brain where with the participation of polisinaptichesky bonds of a reticular formation slozhnokoordinirovanny reaction of muscles of bronchial tubes, throats, a thorax, a stomach, a diaphragm will be organized. An initial phase of this reaction is the deep breath. Then there comes the phase of an intense exhalation at the closed glottis and the reduced bronchial tubes.
During this period intrathoracic pressure increases, reaching 140 mm of mercury. and more. At the next moment voice folds are disconnected and there is a tolchkoobrazny prompt exhalation, as a rule, through a mouth (the nasal cavity is closed by a soft palate and a uvula). At the same time the speed of the movement of air in respiratory tracts by 20 — 30 times exceeds that at usual breath, reaching in a trachea, average and large bronchial tubes of 30 — 40 m/s, and in a glottis — 50 — 120 m/s; rate of volume flow of an air flow reaches 12 l/sec. From respiratory tracts in an oral cavity slime and accumulations of the elements forming a phlegm, and also the alien substances which got into airways are fond of the thrown-out current of air. In an expiratory phase To. can be discontinuous, consisting of several repeated pushes; the bystry change of pressure and speed of air connected with it in respiratory tracts promotes a separation from walls of bronchial tubes of the particles of a phlegm and alien particles pasted to them and to their advance to a trachea and a throat. Upon completion of a phase of a prompt exhalation the single act comes to an end To., which, however, can repeat in a row several times (tussive reprises). At severe convulsive cough vomiting because of irradiation of irritation on the emetic center is sometimes observed.
Formation of a tussive reflex is under control of activity of a cerebral cortex; it can be suppressed or caused randomly. In most cases To. it is caused by irritation of receptors of respiratory tracts and pleurae. However To. it can be connected with excitement of c. N of page, and also with irritation of the receptors located out of a respiratory organs. Respectively allocate To. central origin (including. To. as display of neurosis, or neurotic To.) and reflex To., caused by irritation of receptors of acoustical pass, a gullet and receptors of other localization out of respiratory tracts.
Frequency and intensity To. depend not only at most an irritant, but also on its localization.v a respiratory organs, and also on excitability of tussive receptors, edges has individual distinctions and fluctuates at the same person depending on a form of a disease, a phase of disease, character patol, process. The most sensitive reflexogenic zones are the back surface of an epiglottis, a front interarytenoid surface of a throat, area of voice folds (sheaves) and subdepository space» and also bifurcation of tracheas and the place of branches of lobar bronchi. The number of receptors in bronchial tubes decreases parallel to reduction of their diameter, and already branchings of segmental bronchi are a little sensitive to irritations. To cause To. the irritation of the pulmonariest fabric in an experiment does not work well. At patol, the processes limited on localization to a pulmonary parenchyma To. it is possible or at hit of a phlegm, in rather large bronchial tubes, or during the involvement in patol, process of a pleura. The most sensitive reflexogenic zones of a pleura are located in radical sites and costal and phrenic sine, but the tussive reflex is caused at irritation and other its sites.
In the diagnostic relation To. in itself is not a specific symptom of any disease, but its value as symptom significantly increases at assessment of character and features of manifestation To., and also at the accounting of the accompanying symptoms. To. happens frequent and rare, weak and strong, painful and painless, constant and periodic. Depending on existence or lack of a secret distinguish cough dry and with expectoration.
Constant To. it is observed at hron, diseases of a throat, throat or trachea, hron, bronchitis, at long stagnation of blood in lungs at patients with pathology of bodies of blood circulation. In the period of an aggravation hron, a tracheobronchitis sensitivity of tussive receptors to irritations increases also To. it is provoked by the low-irritating smells and even change of temperature and humidity of inhaled air. Periodic To. happens at smokers and alcoholics, at patients with pneumonia, bronchial asthma, emphysema of lungs, at acute respiratory diseases and other diseases. A single attack strong To. arises at inhalation of smoke and other irritating substances, at hit in respiratory tracts of a foreign body or pieces of food.
To. can be various on sonority. Rough barking To. it is caused by swelling of a mucous membrane of a throat and voice folds; it is often observed at acute laryngitis, and at children — at a true and false croup. The barking Km as a rule, is combined with hoarseness of a voice or an aphonia.
Differs in a peculiar feature convulsive, or convulsive, To., arising attacks, more often at night. Convulsive To. it is characterized by the tussive pushes which are quickly following one after another interrupted by long and loud breaths; quite often attacks To. repeat (reprises) and are followed by vomiting. Such To. it is typical for whooping cough (see).
At children at a tumorous bronchadenitis appears bitonalny To., at Krom the musical high overtone joins rough main tone.
Quite sharp To. happens at a tracheobronchitis, pleurisy, pneumonia; silent — at paralysis or destruction of voice folds (it is combined with an aphonia), existence of a tracheostoma, and also at considerable weakness of the patient. A tussiculation — low-sonorous, weak and short To. — points to long weak irritation of tussive receptors. Especially often the tussiculation is observed at hron, pharyngitis and at an initial pulmonary tuberculosis. The deaf weakened To. it is typical for hron, the obstructive bronchitis complicated by emphysema of lungs.
Dry cough (To. irritations, useless To.) it is characteristic of an expiratory stenosis of a trachea and large bronchial tubes (hoarse To.), for damage of a pleura, a mediastinum, for pathological processes (often not of inflammatory) bronchial tubes in a circle, upper respiratory tracts and conductors of sensory nerves (a prelum a tumor, increased limf, nodes, an aortic aneurysm, etc.). It is observed also at pheumothorax, hit in respiratory tracts of a foreign body, and also at the disseminating and fibroziruyushchy processes in lungs (cancer, tuberculosis, Beck's sarcoidosis, collagenoses). Dry To. it can be observed also at the very beginning of development of acute laryngitis, tracheitis, bronchitis, pneumonia and as an equivalent of an attack of bronchial asthma; however at these diseases it is more often about To. with a scanty phlegm, than about dry
K. K. with a phlegm it is observed at the diseases which are followed by hypersecretion of bronchial slime (bronchitis), formation of exudate (bronchitis, pneumonia) or liquids (e.g., at break of a parasitic cyst) a Large number of a phlegm happens in the presence of the cavities (bronchiectasias, abscesses) which are reported with bronchial tubes in which products of secretion, exudation and fabric disintegration collect. To.
with a phlegm usually arises in process of accumulation in bronchial tubes of the irritating products (slime, pus, blood, etc.) also stops after expectoration.
At hron, an inflammation of upper respiratory tracts, especially at smokers, To. it is usually observed in the morning. It is connected with accumulation of a phlegm in a night and with its difficult expectoration. Quite often such To. call cough during the washing though it can appear also in earlier hours. To. at night it can be connected with fiziol, night strengthening of a tone of a vagus nerve at the diseases which are followed by a bronchospasm (an allergic bronchitis, bronchial asthma, cardial asthma) and at localization patol. process in zones of the increased receptor sensitivity (increase bronkhopulmonalny limf, nodes, a pulmonary tuberculosis, etc.), and also with advance of a phlegm by gravity from cavities (bronchiectasias, abscesses) in bronchial tubes at horizontal position of the patient (a so-called drainage situation, or a postural drainage).
Diagnostic value has character of separated phlegms (see). To. with a vitreous, mucous, viscous phlegm it is observed at tracheitis and an acute bronchitis at the beginning of a disease; further the phlegm becomes mucopurulent. At acute focal pneumonia the mucopurulent phlegm (sometimes bloody) separates, at croupous — a prune juice sputum. At hron, pneumonia with bronchiectasias, abscess and gangrene of lungs the phlegm purulent, quite often has off-flavor, sometimes fetid. In far come stages of a pulmonary tuberculosis in the presence of a cavity cough happens to a purulent, monetoobrazny phlegm. Cough with a bloody phlegm is observed at a heart attack of a lung, tuberculosis, cancer of bronchial tubes, at developments of stagnation in a small circle, at heart diseases (see. Pneumorrhagia ). The phlegm having an appearance of crimson jelly belongs to late symptoms of bronchogenic cancer, at Krom blood in a phlegm is defined microscopically more often.
Cough not only does not perform physiologically useful drainage function, but can exert on an organism and an adverse effect. Frequent persistent To., especially in the form of long attacks, is followed by increase in intrathoracic pressure and can promote gradual development hypertensia of a small circle of blood circulation (see), emphysemas of lungs (see), to formation pulmonary heart (see). Build-up of pressure in veins of a big circle of blood circulation in time To. sometimes leads to emergence of small hemorrhages in vessels of scleras, in system of bronchial veins, etc. The attack of a severe cough can be complicated by a faint, a loss of consciousness, disturbances of a cordial rhythm and even an epileptiform attack (see. Bettolepsy ). At violent emphysema of lungs strong To. can cause a rupture of alveoluses and pheumothorax (see).
In rare instances cough can promote distribution of infectious process, napr, tuberculosis, from one site of lungs in others.
In therapeutic actions at cough of any nature crucial importance has treatment of a basic disease. The cough providing an effective drainage of bronchial tubes should not be suppressed. In these cases strengthen cleaning function K., appointing expectorants (see), broncholitic means. Are applied to calm of painful cough antibechics (see) taking into account that many of them — codeine, dionine, a hydrocodon, Thecodinum, etc. — belong to the drugs of opium group suppressing function of a respiratory center (i.e. can be contraindicated at respiratory insufficiency) and causing addiction.
In need of long prescription of medicines, suppressing To., non-narcotic antibechics with preferential influence on tussive receptors and to a lesser extent on receptors of a myelencephalon are preferable. They reduce cough and do not reduce department of a phlegm (glautsin, libexinum, etc.)
Bibliography: Zlydnikov D. M. To a question of the mechanism of cough, Vestn, otori-nolar., No. 3, page 31, 1956; Mikhaylov F. A. About cough, Klin, medical, t. 44, No. 6, page 114, 1966.
V. P. Silvestrov.