Expiratory dyspnea

The symptom, which is manifested by difficulty and prolongation of the expiratory phase of breathing - exhalation - and causes a feeling of discomfort when breathing, is defined in medicine as expiratory dyspnea.

Dyspnea is defined by the American Thoracic Society as "a subjective sensation of discomfort when breathing." [1] Although previous definitions have sometimes conflated this true symptom with physical signs (e.g., "difficulty breathing"), the American Thoracic Society considers dyspnea to be a symptom. Thus, dyspnea can only be described by the person experiencing it.

Causes of the expiratory dyspnea

Why is it difficult to exhale, what can interfere with the flow of air in the airways, that is, what are the causes of dyspnea expiratory character?

In most cases, expiratory dyspnea (dyspnea) is caused by airway obstruction. And the obstruction in this case affects the lower airways: the larynx (below the vocal cords), trachea, bronchi (bronchial tree), terminal bronchioles (distal bronchial branches) and lungs.

Expiratory dyspnea may occur in bronchitis, for more information see - Dyspnea in obstructive and acute bronchitis

This type of shortness of breath is one of the symptoms of respiratory diseases such as tracheitis and allergic tracheobronchitis; obliterative or chronic obstructive bronchiolitis.

Due to narrowing of the lower airway lumen (bronchoconstriction), wheezing on exhalation and expiratory dyspnea occur in bronchial asthma (infectious-allergic and allergic in nature).

In some cases, there may be expiratory dyspnea in pneumonia, mainly caused by Mycoplasma spp, diffuse viral or desquamative interstitial pneumonia - with lesions of the lung parenchyma and fibrosis of the alveoli due to the inflammatory process.

Exhalation difficulty is also caused by: chronic pulmonary emphysema; pulmonary edema (cardiogenic or noncardiogenic); pulmonary eosinophilia with asthmatic syndrome; lung and mediastinal tumor masses (causing compression of the trachea and/or bronchi).

Almost all patients with bronchial asthma and chronic obstructive pulmonary disease (COPD) have mixed, i.e. Inspiratory and expiratory dyspnea, but exclusively expiratory dyspnea is much less common in COPD.

Mixed dyspnea is also a symptom of severe pulmonary edema (caused by left ventricular failure or pneumonia), bronchiectatic disease and bronchoconstrictive syndrome, diffuse primary bronchopulmonary amyloidosis. In newborns, such dyspnea may be the result of an abnormal development of the tracheal cartilage - tracheomalacia, leading to collapse of its walls (tracheal collapse), and in premature infants - respiratory distress syndrome of newborns.

Expiratory dyspnea in children (especially young children) is one of the signs of lower respiratory tract involvement respiratory syncytial infection, as well as stenosing laryngotracheitis and laryngotracheobronchitis.

Patients with severe pneumonia, asthma, COPD exacerbation, pulmonary edema and tumors, and pneumothorax and pulmonary embolism have expiratory dyspnea on exercise.

In addition, this symptom occurs in various variants of congenital muscular dystrophy. Neuromuscular diseases such as myasthenia gravis, amyotrophic lateral sclerosis and, Guillain-Barré syndrome can also lead to weakness of the respiratory muscles with impaired expiratory phase of breathing.

The work of respiratory muscles with difficulty in exhalation is disturbed by pathological changes in the thorax, in particular, in scoliosis of the thoracic spine or flotation fracture of several adjacent ribs.

The etiology of expiratory dyspnea may be related to trauma to the lower airways or damage to them during certain medical manipulations and surgical procedures.

More information in the material - Diseases of the trachea and bronchi: causes, symptoms, diagnosis, treatment

Risk factors

The risk of impaired expiratory phase of breathing is increased in smokers (smoking is the cause of more than 70% of COPD cases); with a tendency to allergic reactions; in immunosuppressive conditions; in the lower respiratory tract affected by viral and bacterial infections; in chest traumas; in cases of chemical and thermal (burn) injuries of the larynx and trachea; in cases of pathological enlargement of pulmonary and bronchopulmonary lymph nodes; in the presence of anomalies and congenital malformations of the bronchopulmonary system, as well as genetically determined cystic fibrosis - cystic fibrosis,

Pathogenesis

During the second phase of breathing - exhalation - the diaphragm and intercostal muscles relax; the chest descends with a decrease in lung volume (due to a decrease in the volume of their alveoli) and an increase in internal pressure. As a result, carbon dioxide and volatile organic compounds are expelled from the lungs. [2] Read more - Fundamentals of Respiratory Physiology

The main in the pathogenesis of expiratory dyspnea pulmonologists consider increased resistance to airflow due to inflammation and remodeling of part of the small airways, which lead to their narrowing: with excess bronchial secretion, weakness and hypertrophy of bronchial muscles, decreased elasticity of lung tissue and in the case of constant compression (for example, in the presence of edema or lung tumor).

In asthma, COPD, bronchial disease, or pneumonia, exhalation velocity - in conditions of narrowed airway lumen or decreased alveolar elasticity - cannot be increased by increasing expiratory effort.

Explains the mechanism of expiratory dyspnea and overinflating (hyperinflation) of the lungs with an increase in their volume at the end of exhalation. Accompanying diseases of the respiratory tract pulmonary hyperinflation, violating the ability of respiratory muscles to create subatmospheric pressure, prevents the displacement of air and increases the load on the main respiratory muscles.

The feeling that breathing requires more effort, experts attribute both to the strengthening of afferent nerve impulses coming from the working respiratory muscles to the medullary respiratory center of the brainstem (to the ventral respiratory group controlling involuntary exhalation) and to the disruption of efferent motor signals (coming from the motor cortex). [3], [4]

The sensation of chest tightness in asthma is presumably generated by afferent signals coming directly from peripheral lung mechanoreceptors, including lung stretch receptors. These receptors (which send signals via the vagus nerve to the medulla oblongata) trigger the Gehring-Breyer reflex, which reduces respiratory rate to prevent lung overinflating. Increased excitation of stretch receptors also increases pulmonary surfactant production. [5]

And the pathogenesis of expiratory wheezes is due to the vibration of the airway walls, which is caused by the turbulence of the airflow passing through a narrowed or compressed segment of the airway.

Epidemiology

Dyspnea is a common symptom of cardiopulmonary disease; according to WHO, approximately 10-25% of middle-aged and older people experience dyspnea in daily life. [6]

As clinical practice shows, the presence of expiratory dyspnea is noted in 25% of cases of lower respiratory tract infections, in almost 18% of COPD cases and in 12.6% of patients with bronchial asthma.

Symptoms

The first signs of dyspnea of the expiratory type - a feeling of discomfort when breathing, due to difficulty in exhaling.

In moderate obstruction of the lower airways, there is a decrease in respiratory rate, an increase in respiratory lung volume (inspiratory-expiratory volume) and a slight lengthening of exhalation. In severe obstruction, breathing becomes more rapid, exhalation is significantly prolonged, and auxiliary respiratory muscles (sternocervical and ladder muscles) are tense.

Natural inspiratory lung noises - vesicular breathing - on lung auscultation in patients with expiratory dyspnea may be normal, but bronchial breathing (i.e., expiratory breathing) is altered. For example, in bronchial asthma, vesicular breath sounds may be normal but with prolonged exhalation; patients with bronchitis may have audible wheezing at various locations in the chest. Wheezing (stridor) is also seen, and crepitating (crunching) wheezes or longer expiratory periods with decreased breath sounds may be heard in patients with COPD.

Mixed dyspnea (inspiratory and expiratory) causes complaints of not having enough air to breathe. An attack of such dyspnea causes the patient to assume a forced position.

Depending on the underlying condition, shortness of breath is accompanied by other symptoms including fever, cough with thick sputum, pain and tightness in the chest, cyanosis and pale skin.

And an attack of expiratory dyspnea in the form of paroxysmal nocturnal dyspnea - with short inhalation and demanding exhalation - occurs due to increased pressure and fluid stasis in the lungs (in patients with congestive heart failure) or due to bronchospasm in obstructive bronchitis, asthma and COPD.

Diagnostics of the expiratory dyspnea

It should be borne in mind that it is not the diagnosis of the symptom that is performed, but the respiratory examination identifies the disease in which the symptom occurs.

In addition to the mandatory collection of anamnesis, auscultation and percussion of the lungs, instrumental diagnostics is used, including: spirometry (to measure lung function - their total capacity, functional residual capacity, residual volume and vital capacity of the lungs); pneumotachography (to detect violations of bronchial patency), tracheobronchoscopy, lung X-ray, CT chest.

Laboratory tests are carried out: general and biochemical blood tests, blood tests for acid-base status (pH level), for the presence of specific antibodies (IgA); sputum bacteriopsy, bronchoalveolar lavage and other additional studies.

To determine the correct treatment tactics, differential diagnosis is of particular importance.

Treatment of the expiratory dyspnea

Treatment should be etiologic, that is, directed at the underlying disease. Read more in the publications:

• Treatment for tracheitis
• Treatment of chronic obstructive bronchitis
• Antibiotics for bronchitis
• Inhalation for chronic and obstructive bronchitis in adults and children
• Physiotherapy for chronic obstructive pulmonary disease
• Medications for bronchial asthma
• Treatment of acute pneumonia

Bronchodilators (cholinolytic drugs) and bronchodilators (anticholinergic agents and β2-adrenoreceptor agonists) are used to dilate and relax the airways in case of airway obstruction.

In severe pulmonary emphysema and its unsuccessful conservative therapy may be performed bullectomy - surgery to reduce the volume of the lungs.

About what to do if it is difficult to breathe, read in the article - How to get rid of shortness of breath: treatment with medicines, folk remedies

Complications and consequences

A complication of expiratory dyspnea can be:

• development of hypoxemic respiratory failure with decreased oxygen content in the blood;
• impaired ventilation of the lungs - hypoventilation (the lungs cannot adequately remove carbon dioxide, and it accumulates, causing hypercapnia), and this, in turn, leads to acid-base respiratory distress with an increase in the partial pressure of carbon dioxide in arterial blood (PaCO2) - respiratory acidosis. In this; there may be narrowing of pulmonary arterioles, decreased blood pressure and myocardial contractility (with the threat of cardiac arrhythmias), and increased intracranial pressure.

Prevention

The best method of preventing chronic obstructive pulmonary disease is to quit smoking. And in the presence of underlying bronchopulmonary disease to prevent the appearance of such a symptom as expiratory dyspnea is possible only by treating the disease in its early stages.