Dyspnea

Evaluation of complaints of shortness of breath should begin with observation of the patient's respiratory movements at rest and after physical exertion.

The definition of the concept of dyspnea causes controversy and ambiguous interpretations. Dyspnea is defined as a feeling of insufficient breathing, difficulty performing respiratory movements, shortage of air, etc. It is important to emphasize that dyspnea is a purely subjective phenomenon and cannot be defined in terms used to assess blood gases or ventilatory disorders. Dyspnea is often found in neurotic disorders, it can be a component of hyperventilation syndrome or precede its development. Shortness of breath is the central phenomenon in the clinical manifestations of psychogenic dyspnea. The degree of severity can vary: with an increase in the sensation of dyspnea, hyperventilation manifestations occur, which bring numerous symptoms to the clinical picture. Dyspnea, or dyspnea, is the most common, leading symptom of panic attacks. According to preliminary studies, in patients with various vegetative disorders, unpleasant sensations in the respiratory sphere, respiratory discomfort, including dyspnea, occur in more than 80% of cases.

The American Thoracic Society has proposed the following definition: dyspnea is a concept that characterizes the subjective experience of respiratory discomfort and includes qualitatively different sensations that vary in intensity. This subjective experience is the result of the interaction of physiological, psychological, social, and environmental factors and may lead to secondary physiological and behavioral responses.

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The most common causes of shortness of breath

1. Diseases of the lungs and respiratory tract
   • Chronic bronchitis and emphysema
   • Bronchial asthma
   • Bronchiectasis
2. Diseases of the lung parenchyma
   • Respiratory failure of any etiology
   • Pneumonia
   • Lung tumors
   • Alveolitis
   • Sarcoidosis (stages I, II)
   • Condition after extensive pneumonectomy
3. Other conditions
   • Pneumothorax
   • Pulmonary embolism
4. Cardiovascular diseases
   • Heart failure of any etiology
   • IHD: angina pectoris, myocardial infarction
   • Arrhythmias of various etiologies
   • Myocarditis
   • Heart defects.
5. Chest pathology
   • Pleural effusion
   • Neuromuscular diseases (including those accompanied by paresis or paralysis of the diaphragm)
6. Anemia
7. Severe obesity
8. Psychogenic factors

How does shortness of breath develop?

Dyspnea (dyspnoe) is a disorder of the frequency, rhythm and depth of breathing, accompanied by increased work of the respiratory muscles and, as a rule, subjective sensations of lack of air or difficulty breathing, often cyanosis (in pulmonary diseases usually "warm" due to secondary compensatory erythrocytosis and dilation of small vessels due to hypercapnia). An objective sign of dyspnea is increased respiratory rate (more than 18 per minute). Dyspnea is often felt as a feeling of tightness in the chest when inhaling, the inability to take a deep breath and completely release air when exhaling.

Any dyspnea is based on excessive or pathological activity of the respiratory center. It occurs as a result of irritation of the receptors located in the respiratory tract, the lungs themselves, and the respiratory muscles. However, in general, the causes of unpleasant subjective sensations during dyspnea remain unclear.

In patients with lung diseases, dyspnea is closely related to a disorder of the respiratory mechanism. In this case, a large effort during inhalation, observed, for example, with increased rigidity of the bronchi and lungs (difficulty in bronchial patency, pulmonary fibrosis) or with a large chest volume (pulmonary emphysema, an attack of bronchial asthma), leads to increased work of the respiratory muscles (in some cases with the inclusion of additional muscles).

In respiratory diseases, dyspnea has different origins. It can be associated with an obstruction to the normal passage of air in the respiratory tract. Another reason may be a decrease in the respiratory surface of the lungs (compression due to accumulation of fluid or air in the pleural cavity, exclusion of part of the lung from gas exchange due to inflammatory infiltrates, atelectasis, infarction, tumor, thoracoplasty, lung resection, partial loss of plasticity of the lungs). All this leads to a decrease in ventilation, a decrease in VC. As a result, the concentration of carbon dioxide in the blood increases, acidosis develops. In interstitial pneumonia, pulmonary edema, the situation may be aggravated by the appearance of an alveolar-capillary block.

In heart diseases, shortness of breath is a manifestation of circulatory failure and is caused by a number of factors that excite the respiratory center. Shortness of breath occurs when gas exchange is disrupted and under-oxidized products accumulate in the blood. This leads to increased frequency and depth of breathing. Particularly severe gas exchange disorders occur when blood stagnates in the pulmonary circulation. In acute left ventricular failure, interstitial edema initially develops, followed by alveolar edema.

Three pathophysiological mechanisms of respiratory failure can be identified.

1. Hyperventilation with decreased saturation of arterial blood with oxygen (hypoxemia) or oversaturation with carbon dioxide (hypercapnia) during physical exertion, staying at high altitudes, heart failure, as well as with increased oxygen demand in thyrotoxicosis and fever.
2. Relative hyperventilation with a decrease in the respiratory surface of the lungs.
3. Mechanical ventilation disorders (stenosis of the upper respiratory tract, bronchial obstruction, emphysema, phrenic nerve paresis and other lesions of the respiratory muscles, heart failure, kyphoscoliosis).

The bulbar center is affected by both an increase in carbon dioxide tension, a decrease in oxygen content, and a shift in pH toward the acidic side. The accumulation of carbon dioxide is of predominant importance. With prolonged hypoxemia, the mechanism of oxygen influence on the carotid sinus is activated. In addition to chemical factors, the volume of respiration is regulated by reflex influences from the lungs, pleura, diaphragm, and other muscles.

Ultimately, the sensation of lack of air can be formed by the following mechanisms: increased sense of respiratory effort, stimulation of irritant receptors of the respiratory tract, hypoxemia, hypercapnia, dynamic compression of the respiratory tract, afferent imbalance, stimulation of baroreceptors of the pulmonary vessels and the right atrium.

Epidemiology

In the United States, more than 17 million patients seek medical attention for shortness of breath each year. The prevalence of shortness of breath in the general population varies and depends on age. In the 37-70 year old population, it ranges from 6 to 27%. In children, due to the pathophysiological characteristics of childhood, shortness of breath can reach 34%. During the first months of life, shortness of breath is very rare. After two months of life, the incidence of new-onset shortness of breath increases significantly, reaching a maximum between the second and fifth months of life, and in most cases, shortness of breath during the first three months of life is associated with the respiratory syncytial virus. Epidemiological studies of children have determined that by the age of six, shortness of breath remains in approximately 40% of children who suffered from it in the first three years of life.

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Types of shortness of breath

Dyspnea can be subjective and objective: a combination of both is also possible. Subjective dyspnea is understood as a subjective feeling of a lack of air when breathing. Objective dyspnea is determined by objective research methods and is characterized by a change in the frequency, depth or rhythm of breathing, as well as the duration of inhalation or exhalation.

The type of dyspnea can be assumed already by studying the anamnesis; physical examination allows obtaining important additional information. A distinction is made between inspiratory (difficulty inhaling), expiratory (difficulty exhaling) and mixed dyspnea.

• Inspiratory dyspnea occurs when there are obstacles to the flow of air into the trachea and large bronchi (swelling of the vocal cords, tumors, foreign body in the lumen of the bronchi).
• Expiratory dyspnea is most typical for pulmonary emphysema or bronchospasm (for example, during an attack of bronchial asthma). In emphysema, dyspnea is associated with the so-called expiratory collapse of the bronchi: since during inhalation the pressure of the pulmonary parenchyma (with a large residual volume of air) on the bronchi of medium and small caliber is significantly less than during exhalation, then with insufficient rigidity of the tissue framework of the bronchi, which is very typical for pulmonary emphysema, they collapse, which leads to difficulty in removing air from the alveolar sections of the lungs. With bronchospasm, removing air from the alveoli is difficult, which is associated with an increase in air pressure on the already narrowed (spasmed) bronchi of medium and small caliber during exhalation.
• The mixed variant of dyspnea is observed most often; it is characteristic of chronic respiratory and chronic heart failure, developing in the late stages of diseases of the respiratory and circulatory organs.

A special variant of dyspnea is specifically distinguished, called suffocation - an attack of extreme dyspnea, when all breathing parameters (frequency, rhythm, depth) are disturbed to the maximum extent. Most often, such dyspnea accompanies an attack of bronchial asthma and acute left ventricular failure (cardiac asthma).

Another type of breathing disorder should be mentioned - its temporary cessation (apnea), which is sometimes observed in obese people, usually during sleep, which is accompanied by loud snoring (Pickwick syndrome). This condition usually occurs in the absence of primary lung disease and is associated with deep hypoventilation of the alveoli due to extreme obesity.

Based on the respiratory rate, a distinction is made between dyspnea with an increased respiratory rate (typhoid), with a normal respiratory rate, and with a decreased respiratory rate (bradypnea).

Shortness of breath in the supine position is called orthopnea (usually associated with pulmonary venous congestion). Platypnea is shortness of breath in a standing or sitting position (usually associated with intracardiac and intrapulmonary shunts and damage to the chest muscles); trepopnea is in the lateral lying position (usually occurs in congestive heart failure).

Shortness of breath can be physiological (due to increased physical activity) and pathological (due to illnesses and poisoning with certain toxins).

The severity of dyspnea in chronic diseases is assessed using the international scale for assessing the severity of dyspnea (Medical Research Count ll Dyspnea Scale).

How is shortness of breath recognized?

Anamnesis data for various diseases primarily reflect the underlying pathology.

Shortness of breath in heart disease reflects circulatory failure, so its severity can be used to judge the degree of failure. Thus, in the initial stages of heart failure, shortness of breath occurs only with physical exertion, climbing stairs or uphill, or walking quickly. Often, the earliest sign of impending left ventricular failure is attacks of excruciating cough at night. As the disease progresses, shortness of breath occurs with minimal physical activity (when talking, after eating, while walking). In severe cases, constant shortness of breath at rest is observed. In the most severe cases, typical nocturnal attacks of paroxysmal suffocation develop, which can end in pulmonary edema. Questioning usually reveals a connection between these attacks and physical effort. They can occur directly during physical activity or several hours after its completion. Depending on the severity of the condition, the resulting orthopnea can last from several hours to several days. As a rule, pain in the heart area appears simultaneously with orthopnea. In patients with aortic insufficiency, dyspnea is sometimes accompanied by profuse sweating (sweat runs in streams). In patients with heart failure, cardiovascular pathology is usually traced in the anamnesis (ischemic heart disease, long-term or high arterial hypertension, heart defects).

Shortness of breath in pulmonary emphysema also occurs initially with significant physical exertion, then gradually progresses. Sometimes it is regarded as cardiac and is treated for a long time with cardiac glycosides, usually unsuccessfully. Anamnesis data in emphysema may indicate the presence of chronic bronchitis, a long history of smoking, long-term contact with pollutants, damaging inhalation professional factors. Primary emphysema is more often observed in men of middle and young age. In secondary emphysema, more typical for old age, pulmonary heart develops. In combination with examination data, diagnosis is usually not difficult.

In most cases of obstructive bronchitis, it is also possible to identify a long history of smoking or contact with agents that damage the respiratory tract, as well as recurrent exacerbations of bronchitis against the background of a respiratory infection.

Shortness of breath in bronchial asthma is usually combined with attacks of suffocation and cough (anamnestic features are presented in the articles "Cough", "Suffocation" and "Bronchial asthma"). The sensation of shortness of breath in patients with asthma usually corresponds to the degree of bronchial obstruction. In patients with obstructive bronchitis, there is no relationship between shortness of breath and the FEV1 value. In elderly patients, asthma is often not characterized by attacks, but by prolonged shortness of breath, similar to that in obstructive bronchitis, pulmonary emphysema. Differential diagnostic signs of bronchial asthma and chronic obstructive bronchitis are presented in the article "Bronchial asthma".

Bronchiectasis is characterized by a large amount of purulent sputum, often associated with bacterial infection.

Obliterating bronchiolitis develops at a young age, usually with contact with acid and alkali vapors. There is no clear connection with smoking. Rheumatoid arthritis is sometimes detected.

In case of oncological damage to the trachea, the main symptom is intermittent dyspnea, disguised as asthma attacks. At the same time, accompanying symptoms are detected, such as cough, hemoptysis, fever and weight loss. These same symptoms can also be present in other tumor lesions of the respiratory tract.

Tracheobronchomegaly (a congenital pathology) manifests itself throughout the patient’s life: in addition to shortness of breath, it is a very loud, persistent cough, complications in the form of pneumonia, bronchitis, and bronchiectasis.

Psychogenic dyspnea usually occurs in patients under 40 years of age and is often combined with neuroses. It is most often intermittent in nature, is not associated with physical exertion, and may be accompanied by agitation, dizziness, impaired concentration, palpitations, and fatigue.

Physical examination

Auscultation of patients with bronchial asthma reveals dry wheezing of an expiratory (sometimes inspiratory) nature. They can be either high, treble, or low, bass, of varying timbre and volume. If sputum accumulates in the bronchi, the auscultatory picture (the number and timbre of wheezing) may change after coughing. In the remission phase, changes may not be detected during physical examination.

Emphysema is characterized by: a barrel-shaped chest in an inspiratory position, dome-shaped protrusions in the supraclavicular fossae, limited chest excursion, a box-like percussion sound, low mobility of the diaphragm, a decrease in the boundaries of absolute cardiac dullness (due to the heart being covered by distended lungs), weak heartbeats and weakened breathing during auscultation of the lungs.

In fibrosing alveolitis, changes in the fingers and toes in the form of “drumsticks” and “watch glasses” are sometimes detected.

Similar clinical signs can be found in systemic pathology with lung damage.

In case of bronchiectasis, the patient may have “drumsticks” and, upon auscultation, coarse, moist, different-sized wheezing.

In a patient with heart failure, signs of underlying cardiac pathology appear during physical examination, and wheezing in the lower sections appears during auscultation of the lungs.

In case of stenosis of large airways, stridor breathing is determined.

Laboratory research

Shortness of breath is accompanied by laboratory changes corresponding to these diseases. Thus, if shortness of breath develops against the background of anemia, then a decrease in hematocrit and other signs of a specific type of anemia are detected. If this is an infectious process, then it is possible to detect leukocytosis with a shift in the formula to the left, an increase in ESR. The tumor process can also be accompanied by an increase in ESR, the appearance of anemia. In case of systemic lesions, corresponding signs of an autoimmune process are detected, an increase in the level of acute phase proteins of inflammation. Thyrotoxicosis is manifested by an increased level of thyroid hormones, autoantibodies to thyroglobulin and thyroid peroxidase in autoimmune thyroiditis.

In case of psychogenic dyspnea, laboratory parameters are normal,

Instrumental research

Bronchial asthma may not be accompanied by any radiographic changes. In the acute attack phase, emphysema is detected (increased transparency of the lung fields and limited mobility of the diaphragm), and with a long course (more often with non-atopic variants or with concomitant bronchitis) - pneumosclerosis and emphysema. Spirometry reveals pulmonary ventilation disorders of the obstructive type, as in chronic obstructive bronchitis. The difference with asthma is the reversibility of bronchial obstruction

Radiological signs of emphysema are a low position of the diaphragm, decreased mobility, increased transparency of the lung fields; a symptom of emphysema in men is a significant decrease in the distance from the lower edge of the thyroid cartilage to the manubrium of the sternum.

In case of bronchial ectasis, X-ray or computed tomography data reveals dilation of the bronchi and thickening of their walls.

In case of heart failure, the X-ray reveals dilated heart contours, congestive phenomena (up to pulmonary edema), and the spirogram shows restrictive pulmonary ventilation disorders. Various disorders (rhythm disorders, conduction disorders, signs of hypertrophy and myocardial blood supply disorders) can be detected on the ECG. Heart defects will be reflected on the EchoCG and PCG.

In case of tumor processes, X-ray examination data and bronchoscopy help to make a correct diagnosis.

In patients with psychogenic dyspnea, instrumental examination does not reveal pathology; the spirogram is normal or with signs of hyperventilation.

Indications for specialist consultation

Bronchial asthma and Quincke's edema are indications for consultation with an allergist.

In case of acute bronchiolitis, dust bronchitis, pulmonary emphysema, pleural lesions, interstitial lung diseases, cystic fibrosis, a consultation with a pulmonologist is indicated; in case of chronic obstructive bronchitis, a consultation with a pulmonologist and allergist is indicated.

The appearance of stridor breathing, suspicion of laryngeal stenosis, retropharyngeal abscess, or foreign body require consultation with an otolaryngologist.

If systemic pathology is suspected, a consultation with a rheumatologist is indicated, for a tumor process - an oncologist, for tuberculosis and sarcoidosis - a phthisiatrician, for anemia - a hematologist, for dyspnea of central origin - a neurologist. A consultation with a psychiatrist is indicated for psychogenic dyspnea.