Cough

Cough (Latin: tussis) is a voluntary or involuntary (reflex) jerky, forced, sonorous exhalation that occurs when mucus accumulates in the respiratory tract, irritating gaseous substances are inhaled, or foreign particles enter the trachea or bronchi. The purpose of the reflex is to clear the respiratory tract with a strong, sharp exhalation.

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Mechanism of cough development

Cough occurs in response to irritation of cough receptors located in the larynx, mucous membrane of different parts of the respiratory tract, but above all - the trachea and bronchi (especially in the area of the tracheal bifurcation, bronchial branches), as well as the pleural sheets. Irritation of cough receptors causes a deep breath, after which the vocal cords close and the respiratory muscles and abdominal muscles tense up, which creates high positive intrathoracic pressure and, consequently, high pressure in the respiratory tract. In this case, the posterior membrane of the trachea bends inward. Then the glottis opens sharply, and the pressure difference leads to the creation of an air flow, the speed of which at different levels of the bronchial tree can fluctuate from 0.5 to 50-120 m / sec (hurricane speed). An air flow of such force helps remove mucus and foreign bodies.

The causes of cough are as follows: irritation of cough receptors is caused by mechanical, chemical and thermal effects, as well as inflammatory changes, primarily in the respiratory tract, including those developing under the influence of the above factors.

So, if a child coughs every 3 minutes, and the cough itself has a whistling sound, this is typical of whooping cough. The peculiarity of coughing in whooping cough consists of a whole series of short exhalation movements, lasting several minutes and interrupted from time to time by a whistling inhalation; it also happens that a series of these exhalation movements, which constitutes a coughing attack, can last from 2-3 minutes or more. A child coughing every 3 minutes sometimes also indicates an allergy or bronchial asthma, especially if there is a family history of allergic diseases.

Inflammation leads to irritation of cough receptors due to swelling, hyperemia, exudation with the release of a wide range of biologically active substances, as well as due to the secretion of mucous membrane cells, mucus, blood, pus located in the lumen of the respiratory tract - the most common factors irritating cough receptors. Inflammation sometimes affects both the respiratory tract (larynx, trachea, bronchi, bronchioles) and the alveoli (for example, pneumonia, lung abscess).

• Mechanical irritants - dust and other small particles, as well as obstruction of the airways due to compression and increased tone of the smooth muscle cells of their walls.
  • Tumors of the mediastinum, lungs, enlarged lymph nodes of the mediastinum, aortic aneurysm, endobronchial tumors cause compression of the bronchi and trachea from the outside, leading to the appearance of a cough.
  • Significant enlargement of the left atrium (usually associated with a heart defect) leads to irritation of the recurrent laryngeal nerve.
  • Mechanical irritation is also caused by contraction of the smooth muscle cells of the trachea and bronchi, for example during an attack of bronchial asthma.
  • An enlarged thyroid gland can lead to mechanical irritation of the larynx and trachea.
• Chemical irritants - inhalation of various substances with a strong odor, including cigarette smoke and too intense a perfume. In addition, chemical irritation is possible with reflux esophagitis, when the contents of the stomach enter the larynx and trachea (aspiration).
• Thermal irritation - coughing occurs when inhaling very cold and very hot air.

Due to the wide variety of pathological conditions accompanied by coughing, the question arises of differentiating different types of this symptom. To do this, its productivity, time of appearance and duration, volume and timbre, dependence on food intake, physical, psycho-emotional stress and other provoking factors are assessed.

A correctly collected anamnesis in many cases allows to make a correct preliminary diagnosis. When collecting anamnesis it is advisable to dwell on some points. It is necessary:

• determine what the onset of the disease is associated with (whether it was an acute respiratory infection, contact with a pollutant or a potential allergen);
• determine the duration of the cough, its frequency (sometimes it is constant, for example, with inflammation of the larynx, bronchogenic cancer, with metastases in the lymph nodes of the mediastinum, with some forms of tuberculosis, but more often it bothers periodically);
• establish the presence of accompanying symptoms (fever, nasal discharge, itchy eyelids, asthma attacks, episodes of wheezing, heartburn or belching, swelling of the legs, etc.);
• determine the presence of sputum and its nature;
• find out whether seasonal exacerbations are typical:
• find out whether the patient smokes, and whether there is exposure to occupational hazards or unfavorable environmental factors;
• find out whether the patient is taking drugs from the ACE inhibitor group. Reflex coughing is usually paroxysmal, dry (a feeling of dryness and irritation in the throat appears before the attack) and is not associated with pathology of the bronchopulmonary system. It is often provoked by a previous acute respiratory viral infection. Such coughing occurs more often in people with a labile nervous system, autonomic dysfunction, against the background of stressful situations, with a decrease in mucus production in the upper respiratory tract (which is facilitated by emotional factors, smoking, dry air, hyperventilation). In such patients, a long uvula, hypertrophy of the palatine tonsils, gastroesophageal reflux can be detected.

Tracheobronchial dyskinesia is manifested by persistent, dry, barking cough. It is often characterized as paroxysmal tubal cough: it occurs during physical exertion, laughter, against the background of a cold, can intensify in the prone position, accompanied by inspiratory dyspnea, when an attempt at forced exhalation intensifies the symptoms. It can be combined with bronchial asthma and other diseases.

Epidemiology

There are no epidemiological studies examining the frequency of cough regardless of the nature of the disease. However, up to 25% of patients seeking medical care suffer from respiratory diseases; in most of these cases, one of the symptoms of the disease is coughing. Since there are about 50 causes of cough, we can say that this symptom is highly frequent.

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Classification

A cough is considered acute if it lasts less than 3 weeks and chronic if it bothers the patient for more than 3 weeks. However, this division is relative. For example, a cough during an exacerbation of chronic bronchitis with adequate treatment can last less than 3 weeks.

A distinction is also made between dry (without the release of sputum) and wet (with the release of sputum of various types).

According to clinical characteristics, the following are distinguished:

• bitonal (the sound has two tones - low and an additional high one), observed as a sign of compression of the trachea and large bronchi:
• barking (loud, abrupt, dry), occurs when the larynx or trachea is affected, sometimes combined with hoarseness of voice and aphonia;
• convulsive (paroxysmal, with rapidly following one another shocks, interrupted by a noisy inhalation), can occur with whooping cough;
• spasmodic (persistent dry, with spasm of the larynx), occurs with irritation of the inferior laryngeal nerve;
• deafness occurs with severe emphysema;
• silent is observed with paralysis or destruction of the vocal cords, with tracheostomy, damage to the recurrent laryngeal nerve;
• resonant, observed in the presence of caverns and other pulmonary cavities in the lungs;
• persistent (with pain in the throat).

The presence or absence of sputum is an important diagnostic sign. In diseases such as laryngitis, dry pleurisy, compression of the main bronchi by enlarged bifurcation lymph nodes (tuberculosis, lymphogranulomatosis, cancer metastases, etc.), the cough is dry. In some cases, it may be dry only at the onset of the disease (bronchitis, pneumonia, lung abscess, tuberculosis, bronchogenic cancer, etc.).

In cases of bronchitis, abscess, cavernous tuberculosis, chronic bronchitis, morning discharge of sputum accumulated overnight in the cavities and bronchi is noted. In the case of bronchiectasis, if it is located in the left lung, sputum is discharged in the position on the right side, and vice versa. If bronchiectasis is in the anterior parts of the lungs, sputum is discharged better in the supine position, and in the posterior parts - on the stomach.

Nocturnal coughing is observed, for example, with enlarged mediastinal lymph nodes (lymphogranulomatosis, tuberculosis, malignant neoplasms). In this case, the enlarged lymph nodes irritate the reflexogenic zone of the tracheal bifurcation, and the cough reflex is most pronounced at night, during the period of increased vagus nerve tone. Nocturnal coughing attacks in bronchial asthma are also associated with increased vagus nerve tone.

Blood may be found in sputum. The release of blood with sputum, or hemoptysis, is most often observed in pulmonary diseases (tumor, tuberculosis, pneumonia, abscess, bronchiectasis, mycoses, including actinomycosis, as well as influenza) and cardiovascular pathology (heart defects, thrombosis or embolism of the pulmonary artery). In addition, hemoptysis may occur in hematological diseases, systemic autoimmune pathology and some other conditions.

Complications of this symptom are possible, the most common of which are insomnia, hoarseness, sweating, muscle and bone pain, headache, and urinary incontinence. When coughing, inguinal hernias may enlarge and diaphragmatic hernias may develop. Serious complications include the development of secondary spontaneous pneumothorax and cough-syncope syndrome, previously called bettolepsy syndrome (loss of consciousness, sometimes combined with convulsions, at the height of a coughing attack).

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Types of cough

Depending on the above reasons, a distinction is made between unproductive and productive cough. Productive cough is characterized by the separation of sputum. For some diseases, only unproductive cough is typical, for others, especially inflammatory pulmonary diseases, productive cough usually replaces unproductive cough. In some cases (for example, in acute laryngitis), after the productive phase, a phase of unproductive cough is again noted, which occurs due to a decrease in the sensitivity threshold of cough receptors. In the latter case, the prescription of antitussives rather than expectorants is pathogenetically justified.

Dry cough

Unproductive cough - dry, paroxysmal, exhausting and not bringing relief - is typical for the early stages of acute bronchitis, pneumonia (especially viral), pulmonary infarction, the initial period of an attack of bronchial asthma, pleurisy and pulmonary embolism. Dry cough in acute bronchitis is often preceded by a feeling of tightness in the chest, difficulty breathing. Also, a similar symptom occurs in response to inhalation of substances irritating the mucous membrane or the entry of a foreign body into the lumen of the bronchi or trachea.

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Wet cough

A productive cough is characterized by the release of sputum.

Despite a strong cough impulse, the resulting sputum may not be coughed up. This is usually due to its increased viscosity or voluntary swallowing. Often, a slight cough and a scanty amount of sputum are not considered a sign of illness by the patient (for example, a habitual morning cough with smoker's bronchitis), so the doctor should himself focus the patient's attention on this complaint.

Emergency diagnostic and treatment measures

Usually, coughing as a monosymptom (without suffocation, loss of consciousness, acute pain and other conditions) does not require emergency diagnostic and therapeutic measures. An exception may be the entry of foreign particles and irritating gases into the respiratory tract. In obvious cases, it is necessary first of all to stop contact with the irritating gas and ensure inhalation of clean air, and if a foreign body enters, remove it from the respiratory tract. In complex or unclear cases, laryngoscopy or tracheobronchoscopy may be required.

Who should I contact if I have a cough?

If you suspect an allergic cough, asthma, chronic obstructive bronchitis, allergic and polypous rhinosinusopathy, you should consult an allergist.

Considering the great diagnostic difficulties in diagnosing bronchial asthma in its "cough" variant, it should be remembered that chronic coughing in such patients may be the only symptom. It is usually dry, paroxysmal, nocturnal, during the day any manifestations of the disease may be absent (dry wheezing is not detected during auscultation, and bronchial obstruction is absent according to spirometry data). The presence of eosinophilia in blood and sputum tests helps in making a diagnosis, which in combination with the above clinical manifestations serves as a basis for referring the patient to an allergist. In-depth examination usually reveals bronchial hyperreactivity (according to bronchoprovocation tests), as well as a good response to anti-asthmatic treatment. "Eosinophilic bronchitis" has also been described - a combination of coughing and pronounced eosinophilia of induced sputum without signs of bronchial hyperreactivity. In this case, a good therapeutic effect is also achieved from the use of inhaled glucocorticoids. A final diagnosis can only be made after an examination by an allergist.

An otolaryngologist consultation is necessary for aspiration, ENT pathology (including reflex cough), asthma and chronic bronchitis. A pulmonologist consultation is necessary for interstitial lung diseases, chronic bronchitis, bronchiectasis, pleurisy, and lung abscess. A gastroenterologist consultation is necessary for gastroesophageal reflux disease. A thoracic surgeon consultation is necessary for bronchiectasis and lung abscess.

Consultation with a cardiologist - if there is a suspicion of cardiovascular genesis of cough, consultation with a phthisiatrician - if there is a suspicion of tuberculosis and sarcoidosis; consultation with an oncologist - if there is a suspicion of tumor genesis of the disease, consultation with an endocrinologist if there are signs of thyroid pathology; consultation with a neuropsychiatrist - if there is a suspicion of psychogenic cough.