Diagnosis of chronic obstructive bronchitis

Vermeirc (1996) proposed the following diagnostic criteria for chronic obstructive bronchitis:

• bronchial obstruction proper (clinical manifestations and a decrease in FEV1 to less than 84% and/or a decrease in the Tiffeneau index to below 88% of the predicted values);
• irreversibility or partial reversibility of bronchial obstruction, variability (spontaneous variability) of FEV values by less than 12% during the day;
• consistently confirmed bronchial obstruction - at least 3 times during the one-year observation period;
• age, usually over 50 years;
• the disease is usually detected in smokers or people exposed to industrial air pollutants;
• physical and radiographic signs of pulmonary emphysema;
• steady progression of the disease in the absence of adequate treatment, which is manifested by increasing shortness of breath and an annual decrease in FEV1 by more than 50 ml.

Assessment of the severity of chronic obstructive bronchitis

According to the methodological recommendations "Chronic obstructive bronchitis" of the Russian Pulmonology Society (Moscow, 1997), the severity of chronic obstructive bronchitis is assessed by the FEV1 value. The approach to assessing the severity of patients with chronic obstructive bronchitis is supplemented by determining the stage of the disease based on the overall picture of the severity of the disease, bronchial obstruction disorders according to the recommendations of the American Thoracic Society.

• Stage I. FEV1 is greater than 50% of the predicted value. The disease has a minor impact on quality of life. Patients do not require frequent examinations by a general practitioner. The presence of severe dyspnea in such patients requires additional examinations and consultation with a pulmonologist.
• Stage II FEV1 is 35-49% of the predicted value. The disease significantly reduces the quality of life. Frequent visits to a medical institution and observation by a pulmonologist are required.
• Stage III. FEV1 is less than 34% of the predicted value. The disease dramatically reduces the quality of life. Frequent visits to medical institutions and observation by a pulmonologist are required.

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Examination program for chronic obstructive bronchitis

1. General blood and urine analysis.
2. BAC: content of total protein and protein fractions, fibrin, haptoglobin, seromucoid, sialic acids, bilirubin, aminotransferases, glucose, creatinine.
3. IAC: blood content and determination of the functional capacity of T- and B-lymphocytes, determination of T-lymphocyte subpopulations, immunoglobulins, circulating immune complexes.
4. X-ray examination of the lungs.
5. Spirometry; peak flowmetry or pneumotachometry.
6. ECG.
7. Echocardiography.
8. General and bacteriological analysis of sputum.

Laboratory and instrumental diagnostics

At the initial stages of the disease, a thorough questioning of the patient, assessment of anamnestic data and possible risk factors are of great importance. During this period, the results of an objective clinical examination, as well as laboratory and instrumental data, are of little informative value. Over time, when the first signs of broncho-obstructive syndrome and respiratory failure appear, objective clinical, laboratory and instrumental data acquire increasing diagnostic significance. Moreover, an objective assessment of the stage of disease development, the severity of COPD, and the effectiveness of the therapy is possible only with the use of modern research methods.

X-ray examination

An X-ray examination of the chest organs in two projections is a mandatory method of examination of all patients with COPD. The study allows to identify the presence of signs of broncho-obstructive syndrome, including pulmonary emphysema, some complications of COPD (bronchiectasis, pneumonia, pneumothorax, pulmonary arterial hypertension, chronic pulmonary heart disease, etc.), and indirectly assess the phase of the disease.

An important objective of the study is the radiological differential diagnosis of COPD with diseases also accompanied by prolonged cough and shortness of breath (lung cancer, pulmonary tuberculosis, bronchiectasis, cystic fibrosis, etc.).

In the initial stage of COPD, radiographic changes may be absent. As the disease progresses, distinct radiographic signs of pulmonary emphysema begin to appear, reflecting, first of all, an increase in the airiness of the lungs and a reduction in the vascular bed. Such radiographic signs include:

• increase in the total area of the lung fields;
• persistent decrease in lung transparency;
• depletion of the pulmonary pattern on the periphery of the lung fields;
• the appearance of limited areas of ultra-high transparency, corresponding to large emphysematous bullae;
• flattening of the dome of the diaphragm and significant limitation of its mobility during breathing (less than 3-5 cm);
• reduction in the transverse dimensions of the heart ("drop" or "hanging" heart);
• enlargement of the retrosternal space and others.

The listed radiological signs of pulmonary emphysema are the most important confirmation of the presence of broncho-obstructive syndrome in the patient.

It is more difficult to detect radiographic signs of inflammatory bronchial lesions. In patients with moderate to severe COPD, bronchial inflammation may be accompanied by edema, followed by the development of sclerosis of the peribronchial and interstitial tissue and a peculiar stringiness of the pulmonary pattern. In relatively rare cases, as a rule, with a long-term history of the disease, a reticular deformation of the pulmonary pattern is observed in the form of reticular pneumosclerosis, localized mainly in the lower parts of the lungs. Deformation of the pulmonary pattern is a change in the normal course and shape of the elements of the pulmonary pattern, which forms a randomly branching network. These changes are due to sclerosis of the peribronchial tissues, as well as interlobular and intersegmental septa.

One of the reasons for the impoverishment of the pulmonary pattern is the pronounced impairment of bronchial patency in patients with COPD, often accompanied by the development of microatelectasis. In these cases, the impoverishment of the pulmonary pattern is caused by the simultaneously occurring compensatory overstretching of the lung tissue in a limited area located directly adjacent to the area of microatelectasis.

Finally, in severe cases, radiographic signs of pulmonary arterial hypertension and chronic pulmonary heart disease with hypertrophy and dilation of the right ventricle can be detected. The development of pulmonary arterial hypertension is evidenced by the expansion of all large branches of the pulmonary artery at the roots (more than 1.5-1.6 cm) and a decrease in the caliber of small peripheral arteries of the muscular type (the "caliber jump" symptom). Bulging of the cone of the pulmonary artery trunk in the form of an increase in the 2nd arch of the left contour of the heart is also observed.

The well-known radiographic signs of right ventricular hypertrophy in patients with COPD are not always detected, primarily due to a decrease in the overall transverse size of the heart (“hanging” heart) and the presence of severe emphysema, which increases the retrosternal space and seems to move the wall of the right ventricle away from the anterior chest wall.

X-ray computed tomography (CT) has significant advantages over traditional X-ray examination and allows to identify signs of inflammatory damage to the bronchi and pulmonary emphysema even at the earliest stages of the disease.

For the diagnosis of pulmonary emphysema, for example, the CT method is used with quantitative measurement of the transparency of the lung during inhalation and exhalation. However, despite its high information content, the CT method is rarely used in patients with COPD to confirm damage to the bronchi and pulmonary parenchyma. More often, CT is used to exclude lung tumors, tuberculosis, or other diseases resembling the clinical picture of COPD.

Blood test

Exacerbation of COPD may be accompanied by neutrophilic leukocytosis with a shift in the blood formula to the left and an increase in ESR, although these changes are not mandatory.

In the case of a long-term course of the disease, accompanied by the development of chronic respiratory failure and hypoxemia, signs of secondary erythrocytosis can be determined in the peripheral blood (an increase in the number of erythrocytes, an increase in the hemoglobin content, an increase in blood viscosity and hematocrit (in women more than 47% and in men more than 52%). Against this background, a decrease in ESR to 1-3 mm/h is often noted.

An increase in the serum content of acute phase proteins (a1-antitrypsin, a2-glycoprotein, a2-macroglobulin, haptoglobulin, ceruloplasmin, seromucoid, C-reactive protein), as well as a2- and beta-globulins, is also observed, which indicates the activity of the inflammatory process in the bronchi.

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Sputum examination

Sputum examination in patients with COPD differs little from the corresponding procedure in patients with pneumonia. During microscopy of mucopurulent sputum, which usually corresponds to moderate activity of the inflammatory process in the bronchi, neutrophils (up to 75%) and alveolar macrophages predominate in smears. Purulent endobronchitis is characterized by an even higher content of neutrophils (up to 85-95%) and dystrophically altered cells of the bronchial epithelium.

In patients with severe exacerbation of obstructive bronchitis, purulent sputum or frequent relapses of bronchial inflammation, it is necessary to determine the causative agent of endobronchitis. For this purpose, a bacteriological study of sputum or BAL is performed.

Most often, exacerbations of chronic bronchitis are caused by Haemophilus influenzae or an association of Haemophilus influenzae with Moraxella. This association is especially common in smokers, including people who do not suffer from chronic obstructive bronchitis. In other cases, the causative agent of endobronchitis is pneumococci and other streptococci.

In elderly, weakened patients with severe COPD, staphylococci, pseudomonas aeruginosa and klebsiella may predominate in the sputum.

Finally, in recent years, in relatively young and middle-aged patients, the causative agent of the inflammatory process in the bronchi has increasingly become intracellular (“atypical”) microorganisms: chlamydia, legionella or mycoplasma (in some countries up to 20-30%).

Bronchoscopy

Bronchoscopy is currently one of the most common and informative methods of examining the respiratory tract. The method allows:

1. visually assess the anatomical features of the respiratory tract, the condition of the trachea, main, segmental and subsegmental bronchi;
2. perform a biopsy of the areas of interest in the tracheobronchial tree and obtain material for histological and cytological examination;
3. using aspiration of bronchial lavage water to obtain material for cytological, immunological and bacterioscopic examination
4. for therapeutic purposes, perform bronchial lavage.

Bronchoscopy in patients with COPD is advisable in the following cases:

• in the presence of clinical and radiological signs suspicious of the presence of a lung tumor;
• if the sputum is purulent;
• if tracheobronchial dyskinesia is suspected;
• when determining the source of pulmonary hemorrhage;
• if it is necessary to obtain aspiration material to clarify the etiology of the disease (for example, to identify the causative agent of the infectious process in the bronchi and lungs);
• if necessary, for therapeutic purposes, local administration of drugs (for example, antibiotics) directly into the affected area;
• when performing therapeutic bronchial lavage.

The main contraindications for bronchoscopy are:

• acute myocardial infarction or unstable angina;
• severe circulatory failure stage II6-III and/or hemodynamic instability;
• paroxysmal cardiac arrhythmias;
• arterial hypertension with an increase in blood pressure above 200 and 110 mm Hg or hypertensive crisis;
• acute cerebrovascular accident;
• rapidly progressing hypercapnia;
• unconscious state of the patient, complete lack of contact with the patient;
• acute inflammatory diseases or tumors of the upper respiratory tract (acute laryngitis, laryngeal cancer, etc.);
• insufficient instrumental equipment and training of medical personnel.

It should be emphasized that in patients with arterial hypoxemia and even in patients with disorders of the blood coagulation system and thrombocytopenia, bronchoscopy is quite safe. However, even in the latter cases, biopsy of the bronchial mucosa and pulmonary parenchyma and other invasive procedures are not indicated.

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Research technique

Bronchoscopy, which is a rather complex technical instrumental method of examination associated with a certain risk for the patient, should be performed only in specialized pulmonology departments of hospitals that have a resuscitation service. The examination is carried out in special X-ray bronchology rooms that meet the requirements of a small operating room or surgical dressing room, or in an endoscopic room equipped with a mobile X-ray unit, preferably with an electron-optical converter and a television.

In patients with COPD, the examination is performed using a flexible bronchofiberscope under local anesthesia with 2.4% trimecaine, 2-4% lidocaine, or 1% dicaine. Initially, by irrigation or lubrication with a local anesthetic, anesthesia of the upper respiratory tract - the oropharynx and vocal cords is achieved. After 5 minutes, the bronchofiberscope is inserted through the lower nasal passage or oral cavity and, while inhaling, it is passed through the glottis. By installing aseptics through the bronchoscope, anesthesia of the trachea and large bronchi is achieved.

The examination using a bronchofibroscope includes several stages:

Visual assessment of the condition of the vocal folds, subglottic space, trachea, main, segmental and subsegmental bronchi.

Aspiration of the bronchial contents using a special bronchofibroscope. The bronchial contents are aspirated for subsequent bacteriological, cytological and other types of examination. With a small amount of bronchial secretion, about 20 ml of isotonic solution is first instilled into the bronchus, and then this solution is aspirated together with the bronchial contents, obtaining the so-called bronchial lavage modes, which are subsequently subjected to bacteriological and cytological examination.

Diagnostic subsegmental bronchoalveolar lavage (BAL) for cytological and bacteriological examination of bronchoalveolar contents. To perform this procedure, a bronchofiberscope is brought under visual control to the mouth of the subsegmental bronchus and about 50-60 ml of isotonic sodium chloride solution is introduced into the bronchus through the aspiration channel of the bronchofiberscope, then the fluid coming from the lumen of the bronchus is aspirated into a special polyethylene cup (BAL). The introduction of the solution and aspiration of BAL are repeated 2~3 times. BAL contains cellular, protein; and other components of the alveolar and, to a lesser extent, bronchial contents. To reduce the admixture of bronchial secretions, the second or third portion of the obtained BAL is used for bacteriological and cytological examination, rather than the first. Bronchial biopsy, which is performed using special flexible forceps (direct bronchial biopsy) or a brush with a diameter of about 2 mm (brush, or brush biopsy), brought to the area of interest through the aspiration channel of the bronchofibroscope under visual endoscopic control. After obtaining the biopsy material, smears are immediately prepared from it.

If necessary, transbronchial (intrapulmonary) biopsy and puncture biopsy of the trachobronchial lymph nodes can be performed.

Some of the listed methods are very complex and unsafe for the patient, so the choice of each of them depends on the specific indications and contraindications for bronchoscopy, the equipment of the bronchoscopic room, in particular X-ray television equipment and the qualifications of the endoscopist. A visual assessment of the condition of the trachea and bronchi is carried out in all cases of bronchofibroscopy.

Visual assessment of the condition of the trachea and bronchi

The effectiveness of diagnosing respiratory diseases using bronchoscopy depends not only on the equipment of the endoscopy room and the qualifications of the endoscopist, but also on the correct choice of a particular research method, as well as on the knowledge of the attending physician-therapist of the diagnostic capabilities of the method.

A thorough examination of the vocal folds, subglottic space, trachea and bronchi allows us to assess the anatomical features of the upper and lower respiratory tract, identify inflammatory, neoplastic and other changes in the mucosa, and also assess some dysfunctions of the trachea and bronchi.

Hypotonic tracheobronchial dyskinesia. For patients with COPD, a very typical feature is the violation of the elastic properties of the bronchial walls with the occurrence in some cases of a clinical picture of hypotonic tracheobronchial dyskinesia, the diagnosis of which can only be confirmed endoscopically.

Tracheobronchial dyskinesia is a prolapse of the posterior membranous part of the mucous membrane of these organs into the lumen of the trachea or large bronchi, causing attacks of excruciating, hacking cough, accompanied by an attack of suffocation, stridor breathing and even loss of consciousness. It should be remembered that the only reliable and at the same time accessible method for detecting tracheobronchial dyskinesia is bronchoscopy.

The main endoscopic sign of tracheobronchial dyskinesia is a significant increase in the amplitude of respiratory movements of the membranous wall of the trachea and main bronchi compared to the norm and, accordingly, the degree of their expiratory narrowing. Let us recall that normally, during a quiet exhalation, a slightly noticeable bulging of the membranous part of the mucosa into the lumen of the trachea and bronchi is observed; during inhalation, it returns to its original position. With forced breathing or coughing, the expiratory bulging of the wall of the trachea and main bronchi increases; however, normally, such expiratory narrowing of the lumen does not exceed 30%.

In grade I dyskinesia, there is an expiratory narrowing of the trachea and main bronchi to 2/3 of their lumen while maintaining their normal (round) configuration or some flattening of the lumen. Grade II dyskinesia is characterized by complete closure of the posterior and anterior membranous walls during exhalation and significant flattening of the lumen of the trachea and bronchi.

Tracheobronchial dyskinesia in patients with COPD can significantly increase the resistance of the trachea and main bronchi during forced exhalation and aggravate expiratory obstruction of the airways.

Inflammatory changes in the mucous membrane. Endoscopic signs of inflammatory changes in the mucous membrane of the trachea and bronchi include:

• hyperemia of the mucous membrane of the trachea and bronchi;
• swelling of the mucous membrane;
• bleeding of the mucous membrane during instrumental palpation;
• changes in the vascular pattern of the mucous membrane;
• individual accumulations of mucous or mucopurulent secretions (in catarrhal endobronchitis) or abundant purulent contents in the lumen of the bronchi (for example, in purulent endobronchitis), etc.

The latter sign has an independent and very important diagnostic value and indicates a suppurative process in the lung, although it may not always be caused by purulent bronchitis (pus can enter the lumen of the bronchi from alveolar tissue, abscess, etc.). Such an endoscopic picture always requires further in-depth examination of patients.

According to the most common classification by J. Lemoine (1965), there are three main forms of inflammatory bronchial lesions, revealed by visual examination:

1. Diffuse endobronchitis, characterized by the spread of inflammation to all visible bronchi and the absence of a distal border of mucosal inflammation.
2. Partially diffuse endobronchitis, in which signs of inflammation persist in all visible bronchi, with the exception of the upper lobe bronchi.
3. Limited (local) endobronchitis with clearly defined boundaries of inflammatory changes that are localized in the main and lobar bronchi and are absent in the segmental and subsegmental bronchi.

When studying the visual endoscopic picture, as well as histological and cytological changes within the described forms of endobronchitis, various morphological types of bronchitis can be distinguished:

• simple (catarrhal) endobronchitis;
• purulent endobronchitis;
• atrophic endobronchitis.

Catarrhal (simple) endobronchitis is most common in patients with COPD. In this case, endoscopic examination reveals hyperemia, edema, and increased bleeding of the bronchial mucosa. Purulent endobronchitis is characterized, first of all, by the presence of purulent sputum in the lumen of the bronchi. Finally, atrophic endobronchitis is characterized by thinning and dryness of the mucous membrane, increased vascular pattern, the appearance of characteristic fine folding of the mucosa, desolation and expansion of the mouths of the bronchial glands, and a tendency to bleeding.

When evaluating the results of an endoscopic examination, it should be remembered that a visual examination of the mucosa can only be performed up to the level of 5-7 gradation of segmental bronchi. To obtain information about the damage to smaller bronchi, typical for patients with COPD, one can use the results of a study of bronchial washings or BAL materials.

The examination of BALF obtained during bronchoscopy includes:

1. study of the cellular composition of bronchoalveolar contents;
2. detection of pathogenic microorganisms and, if possible, identification of the causative agent of the infectious inflammatory process and, if necessary,
3. biochemical analysis of BALF (determination of the content of proteins, lipids, enzymes, immunoglobulins, etc.).

The scope of the BALF study is determined each time by the specific diagnostic tasks facing the physician.

Cytological analysis of BALF. To study the cellular composition of the bronchoalveolar contents, BALF is centrifuged at a temperature of +4°C and smears are prepared from the sediment, which are stained with Romanovsky-Giemsa or other dyes and subjected to microscopy. The total number of cells in 1 ml of BALF is counted on a hemocytometer or in an automatic hemoanalyzer.

Normally, the number of cells in 1 ml of BAL is 0.5-10.5 x 10 ⁵. Of these, alveolar macrophages account for more than 90% of all cellular elements, lymphocytes - about 7% and neutrophils - less than 1%. Other cellular elements are extremely rare.

Diagnosis of lung diseases based on the results of cytological examination of BALF is based on changes in the ratio of the main cellular elements (alveolar macrophages, lymphocytes and neutrophils), detection of additional inclusions in these cells and disruption of their morphology and histochemical properties, as well as detection of new pathological cells. In patients with COPD, an increase in the content of neutrophils and lymphocytes is detected in BALF.

Microbiological examination of BALF

Of great practical importance is the detection of pathogens of the inflammatory process in the lungs in the bronchial and bronchoalveolar contents. The diagnostic significance of the microbiological examination of tracheobronchial washings (bronchial lavage waters) and BALF is somewhat higher than the corresponding examination of sputum, since the material for examination can be obtained directly from the lesion. Microbiological examination of BALF has a particularly high diagnostic value in respiratory tract infections caused by Pneumocystis carini, mycobacterium tuberculosis, cytomegalovirus, fungi and other pathogens.

At the same time, the complexity of the bronchoscopy procedure with aspiration of bronchial or bronchoalveolar contents does not yet allow this method to be widely used to identify the causative agent of the inflammatory process and determine the sensitivity of microflora to antibiotics. Therefore, in most cases, microbiological examination of sputum remains preferable.

The bronchoscopic method of obtaining BALF to determine the causative agent of the infectious process is apparently justified only in cases where, for various reasons, sputum is absent or the results of its microbiological examination are questionable, and clinically rapid progression of the inflammatory process and the lack of effect from the prescribed therapy are detected. In clinical practice, the method of microbiological examination of BALF obtained during bronchoscopy is usually used if there are other indications for bronchoscopy.

Biochemical examination of BALF with determination of protein content, sialic acids, haptoglobin, lipid peroxidation products, antioxidants and other substances is a very promising direction for assessing the activity and degree of the inflammatory process in the lungs and bronchi and differential diagnostics of some forms of bronchial damage. However, they have not yet found wide application in clinical practice.

Examination of material obtained during biopsy

Cytological examination. The material for cytological examination is smears obtained during bronchoscopy, brush scrapings from the affected area, aspirates of bronchial contents, BALF, punctures, as well as prints of a biopsied piece of tissue. Cytological examination of the material obtained during biopsy allows with a high degree of probability to diagnose morphological changes in cells characteristic of large groups of lung lesions (for example, acute or chronic inflammatory diseases) or even signs pathognomonic of individual diseases.

Thus, acute inflammatory changes in the lungs and bronchi (bronchitis, pneumonia, abscess) are characterized by the presence of amorphous necrotic masses, a large number of polymorphonuclear leukocytes, reactive structural changes in epithelial cells up to the development of their atypia.

In chronic inflammatory diseases, biopsy material reveals inflammatory infiltrate cells (polymorphonuclear leukocytes, lymphocytes, monocytes, plasma cells, macrophages, etc.), reactive changes in bronchial epithelial cells, and goblet cell hyperplasia.

Histological examination of biopsies. For histological examination, micropreparations are used, prepared from a piece of tissue obtained by direct biopsy of the mucous membrane of the trachea and bronchi, transbronchial, transbronchial and other types of biopsy of the tracheobronchial tree, lung tissue, lymph nodes and pleura.

In patients with COPD, this method can be used to identify characteristic morphological signs of chronic inflammation of the bronchial mucosa - changes in the bronchial epithelium, edema and leukocyte infiltration of the bronchial walls, hyperplasia of the bronchial glands, etc. In patients with atrophic endobronchitis, a decrease in the number of secreting goblet cells and basal layer cells, a significant increase in the content of degenerated cells of the bronchial epithelium, and histological signs of atrophy and metaplasia of the bronchial epithelium are detected.

Evaluation of external respiratory function

The most important method that allows quantitative assessment of the degree of ventilation disorders in patients with COPD, the severity of the disease and the nature of bronchial obstruction is the determination of the external respiratory function (ERF).

The most complete picture of these disorders can be obtained by analyzing the structure of the total lung capacity, determined using the method of total body plethysmography. However, the use of this complex expensive method of research is limited in wide clinical practice. Therefore, the evaluation of FVD in patients with COPD is usually carried out using the method of computer spirography and quantitative analysis of the flow-volume loop. In patients with COPD, this method gives quite acceptable results for assessing the degree of expression of broncho-obstructive syndrome.

According to modern concepts, the main spirographic sign of obstructive syndrome is a slowdown in forced exhalation due to an increase in airway resistance. The main spirogram indicators reflecting these disorders are:

• FEV1 - forced expiratory volume in 1 second;
• FEV1/FVC (Tiffeneau index);
• The average forced expiratory flow rate is 25-75% of the FVC (FEV 25%-75%).
• Maximum forced expiratory flow rate at 25%, 50% and 75% of FVC (FVC25%, FVC50%, FVC75%).

In wide clinical practice, the FEV1 indicator is used, which is considered a marker of broncho-obstructive syndrome. It is believed that a decrease in this indicator below 80% of the expected values is a sign of broncho-obstructive syndrome.

At the same time, it should be remembered that absolute values of FEV1 can decrease not only with bronchial obstruction, but also with severe restrictive disorders due to a proportional decrease in all lung volumes and capacities, including FVC and FEV1. Therefore, a more reliable indicator of broncho-obstructive syndrome is the Tiffio index - the ratio of FEV1 to FVC (FEV1/FVC). A decrease in this indicator of less than 70% in most cases indicates the presence of bronchial obstruction syndrome.

An even more informative indicator of small airway obstruction is probably the SOC25-75% indicator, i.e. the average volumetric airflow rate during forced expiration, measured at the level of relatively small lung volumes. For example, it has been shown that the SOC25-75% indicator is an earlier and more sensitive spirographic marker of increased small airway resistance. In this case, the shape of the flow-volume loop changes: the terminal region of the expiratory part of the loop becomes concave. This indicates that part of the FVC at the level of small lung volumes is exhaled at relatively low volumetric rates, which is typical of small airway obstruction.

At the same time, it should be remembered that the given interpretation of changes in the SOC25-75% indicators and the shape of the final part of the flow-volume loop are not yet generally accepted.

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Assessment of the degree of bronchial obstruction

According to the recommendations of the European Respiratory Society (ERS) in 1995, to assess the degree of bronchial obstruction in patients with COPD and, accordingly, the severity of COPD, FEV1 values are currently used in clinical practice, since, despite all the limitations, this indicator is extremely easy to measure and sufficiently reproducible. Three degrees of reduction in relative FEV1 values are distinguished

• mild degree - FEV1 > 70% of predicted values;
• moderate degree - FEV1 within 50 to 69%;
• severe degree - FEV1 < 50%.

The degree of reduction in absolute values of FEV1 correlates well with the prognosis of the disease. Thus, in patients with moderate signs of airway obstruction and FEV1 greater than 1 l, 10-year mortality slightly exceeds that in individuals who do not suffer from COPD. If in patients with COPD absolute values of FEV1 are less than 0.75 l, mortality only during the first year from the start of observation is about 30%, and over 10 years of observation it reaches 90-95%.

The criteria for classifying patients with COPD by disease stages recommended by the American Thoracic Society and widely presented in modern Russian medical literature are also based mainly on assessing the degree of FEV1 reduction. However, they differ somewhat from the above recommendations of the EPO. According to the proposal of the American Thoracic Society, three stages of COPD should be distinguished:

• Stage 1 - FEV1 is more than 50% of the expected value. The disease slightly reduces the quality of life and requires periodic visits to a general practitioner (therapist). More in-depth examination of patients, including the study of the gas composition of arterial blood and lung volumes, is not required.
• Stage 2 - FEV1 from 35% to 49% of the expected value. There is a significant decrease in the quality of life. Frequent visits to medical institutions, observation by a pulmonologist and determination of the gas composition of the blood, the structure of the total lung capacity, the diffusion capacity of the lungs and other parameters are necessary.
• Stage 3 - FEV1 is less than 35% of the expected value. The disease dramatically reduces the quality of life. Frequent visits to medical institutions, observation by a pulmonologist, in-depth examination of patients, including determination of the gas composition of the blood, the structure of the total lung capacity, the diffusion capacity of the lungs, bronchial resistance, etc. are necessary. If arterial hypoxemia is detected (PaO2 less than 55 mm Hg), patients are candidates for oxygen therapy.

Thus, according to this classification, a decrease in FEV1 to less than 50% can be regarded as a sign of the second stage of the disease (and moderate severity of COPD), whereas according to the criteria of the degree of bronchial obstruction recommended by ERS, the same decrease in this indicator corresponds to severe bronchial obstruction.

The criteria for the degree of bronchial obstruction recommended by the European Respiratory Society are more consistent with the objectives of domestic medical practice, since they guide the doctor to earlier involvement of specialists (pulmonologists) in the management of a patient with COPD. In addition, it would be more correct to indicate in the diagnosis not the stage of the course of COPD, which, by the way, depends not only on the values of FEV1, but the objective functional and morphological characteristics of the disease: the degree of bronchial obstruction and respiratory failure, the presence of pulmonary emphysema, the degree and nature of gas exchange disorders, the presence of signs of pulmonary arterial hypertension, as well as compensated and decompensated chronic pulmonary heart disease, etc.

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Determination of reversibility of broncho-obstruction

To determine the reversibility of bronchial obstruction in patients with COPD, it is advisable to use bronchodilator tests. Most often, the test is performed by inhalation of short-acting beta ₂ - adrenergic receptor agonists:

• salbutamol (2.5-5 mg);
• fenoterol (0.5-1.5 mg);
• tebutamine (5-10 mg).

The bronchodilatory effect is assessed after 15 minutes.

It is also possible to use anticholinergic drugs, for example, ipratropium bromide at a dose of 0.5 mg (inhalation) with measurement of the bronchodilating effect 30 minutes after inhalation.

An increase in FEV1 values by 15% or more indicates the presence of a reversible component of bronchial obstruction, in particular bronchospasm, which certainly makes it advisable to prescribe appropriate bronchodilators for the treatment of these patients. At the same time, it should be borne in mind that the absence of a response to bronchodilator inhalation during a single test is not a reason for not prescribing bronchodilator therapy.

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FEV1 monitoring

Repeated determination of FEV1 (monitoring) allows to finally confirm the diagnosis of COPD, since an annual decrease in FEV1 by more than 50 ml is considered characteristic of this disease. Normally, in mature and old age, starting from 35-40 years, the physiological decrease in this indicator usually does not exceed 25-30 ml per year. The magnitude of the annual decrease in FEV1 in patients with COPD serves as the strongest prognostic indicator indicating the rate of progression of broncho-obstructive syndrome. Moreover, the rate of decrease in FEV1 in patients with COPD depends on the age of the patients, the duration of smoking, the number of cigarettes smoked daily at the present time, the frequency and severity of annual exacerbations of the inflammatory process in the bronchi. It has been shown that clinically significant exacerbations of chronic obstructive bronchitis lead to a sharp decrease in FEV1, which persists for up to 3 months after the relief of inflammation.

Determination of the structure of total lung capacity (TLC)

In most cases, to characterize the degree of bronchial obstruction in patients with COPD, it is sufficient to determine FEV1, FEV1/FVC, and SEF25-75%. However, with a significant decrease in FEV1 (less than 50% of the expected value), as a rule, there is a need for a more detailed study of the mechanisms of reduced pulmonary ventilation. Let us recall that inflammatory and structural changes in large and small bronchi, expiratory tracheobronchial dyskinesia, expiratory collapse of small bronchi, pulmonary emphysema, etc. can contribute to the occurrence of these disorders. A more detailed characterization of the participation of these mechanisms in the reduction of pulmonary ventilation is possible only when studying the structure of the total lung capacity (TLC).

In general, patients with COPD show an increase in total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV), and the RV/TLC ratio. However, not all patients show a proportional increase in TLC and TLC, since the latter indicator may remain normal. This is explained, first of all, by differences in the level of bronchial obstruction. Thus, if obstruction of large airways predominates, an increase in TLC is observed, while TLC usually does not increase. Conversely, with obstruction of smaller peripheral bronchi, both indicators increase in parallel.

Patients with emphysematous COPD have significantly increased RVC and TLC, which reflects pronounced overstretching of the lung parenchyma. These patients show a significant decrease in FEV1, while total bronchial inspiratory resistance remains normal.

In patients with the bronchitis type of COPD, there is a significant increase in residual volume (RV), although total lung capacity (TLC) may remain normal or only slightly increase. FEV1 decreases in parallel with the increase in bronchial resistance during inspiration.

With the prevalence of restrictive disorders, the RVC and TLC remain normal or decrease together with the FRC. With obstructive syndrome, the RVC/TLC increases (more than 35%) and the FRC/TLC (more than 50%). With mixed ventilation disorders, a decrease in the TLC value and a simultaneous increase in the RVC/TLC and FRC/TLC ratios are observed.

It should be remembered, however, that determining the structure of the total lung capacity still remains the prerogative of large specialized medical centers.

[ 35 ], [ 36 ], [ 37 ], [ 38 ], [ 39 ]

Study of the diffusion capacity of the lungs

Impaired lung diffusion capacity is also one of the most important rhythms for the development of arterial hypoxemia in patients with COPD and pulmonary emphysema. Reduced lung diffusion capacity is associated with a decrease in the effective area of the alveolar-capillary membrane, which is very typical for patients with primary pulmonary emphysema. In the bronchitis type of COPD, the lung diffusion capacity suffers to a lesser extent.

Blood gas composition

Determination of the gas composition (PaO2, PaCO2) and blood pH are among the most important characteristics of respiratory failure developing in patients with severe COPD. Let us recall that the cause of arterial hypoxemia (decreased PaO2) in patients with COPD is a violation of ventilation-perfusion relations in the lungs, caused by pronounced unevenness of alveolar ventilation, as well as a violation of the diffusion capacity of the lungs during the development of emphysema. Hypercapnia (increase in PaCO2 > 45 mm Hg), occurring at later stages of the disease, is associated with ventilatory respiratory failure caused by an increase in the functional dead space and a decrease in the function of the respiratory muscles of the diaphragm).

Respiratory acidosis (a decrease in blood pH to less than 7.35), typical for patients with chronic respiratory failure, is compensated for over a long period of time by increasing the production of sodium bicarbonate by the kidneys, which is the reason for maintaining a normal pH level.

The need to determine the gas composition of the blood and the acid-base balance arises, as a rule, in patients with COPD who are in a critical condition, for example, in patients with acute respiratory failure. These measurements are carried out in intensive care units (resuscitation). Since determining the gas composition requires obtaining an arterial blood sample by puncture of the femoral or brachial artery, the method cannot be considered routine and completely safe. Therefore, in practice, a fairly simple method, pulse oximetry, is often used to assess the ability of the lungs to saturate the blood with oxygen (oxygenation).

Pulse oximetry is a method for determining the oxygen saturation of hemoglobin (SaO2) in pulsating arterial vessels.

The method does not allow to estimate the level of PaCO2, which significantly limits its diagnostic capabilities. In addition, it should be remembered that the O2 indicator is influenced by many factors, such as body temperature, hemoglobin concentration in the blood, blood pH and some technical characteristics of the device.

It is believed that when the SaO2 indicator decreases below 94%, it is advisable to perform an invasive determination of the gas composition of arterial blood if the condition requires a more accurate assessment of oxygenation and ventilation of the lungs.

Examination of patients

The examination data depend on the severity and duration of chronic obstructive bronchitis. There are no characteristic features in the early stages of the disease. As chronic obstructive bronchitis progresses due to the development of pulmonary emphysema, the shape of the chest changes, it becomes barrel-shaped, the neck is short, the ribs are horizontal, the anteroposterior size of the chest increases, kyphosis of the thoracic spine becomes pronounced, the supraclavicular spaces bulge. Excursion of the chest during breathing is limited, retraction of the intercostal spaces is more pronounced.

In severe cases of chronic obstructive bronchitis, the jugular veins swell, especially during exhalation; during inhalation, the swelling of the jugular veins decreases.

With the development of respiratory failure and arterial hypoxemia, diffuse warm cyanosis of the skin and visible mucous membranes appears. With the development of pulmonary heart failure, acrocyanosis develops, edema of the lower extremities, epigastric pulsation appear, and orthopnea becomes characteristic.

A typical sign of chronic obstructive bronchitis is a slowdown in forced exhalation. To detect this symptom, the patient is asked to take a deep breath and then exhale as quickly and completely as possible. Normally, a full forced exhalation lasts less than 4 seconds, but in chronic obstructive bronchitis it lasts much longer.

Lung examination

The percussion sound during the development of pulmonary emphysema has a box-like shade, the lower borders of the lungs are lowered, the mobility of the lower edge of the lung is significantly reduced.

Auscultation of the lungs reveals prolonged exhalation and a harsh vesicular breathing pattern. The classic auscultatory sign of chronic obstructive bronchitis is whistling dry rales during normal breathing or forced exhalation. It should be noted that with mild bronchial obstruction, whistling or buzzing rales can only be detected in a horizontal position, especially during forced exhalation ("latent bronchial obstruction"). With severe bronchial obstruction, whistling dry rales are audible even at a distance.

To diagnose bronchial obstruction, one can use the exhalation palpation and match test proposed by B. E. Votchal.

Palpation of the exhalation is performed as follows. In a standing position, the patient inhales deeply, then exhales with maximum force into the doctor's palm, located at a distance of 12 cm from the patient's mouth. The doctor determines the force of the exhaled air stream (strong, weak, moderate), comparing it with the force of his own exhalation. At the same time, the duration of the exhalation is determined (long - more than 6 sec, short - from 3 to 6 sec, very short - up to 2 sec). If bronchial patency is impaired, the force of exhalation is reduced, its duration is lengthened.

The match test is performed as follows. A burning match is placed 8 cm from the patient's mouth and the patient is asked to blow it out. If the patient cannot blow it out, this indicates a significant impairment of bronchial patency.

Cardiovascular examination

When examining the cardiovascular system, tachycardia is often detected, and arterial pressure may be elevated. These changes are explained by hypercapnia with peripheral vasodilation and increased cardiac output.

Many patients have epigastric pulsation due to the right ventricle. This pulsation may be due to hypertrophy of the right ventricle (in chronic pulmonary heart disease) or positional shifts of the heart due to pulmonary emphysema.

Heart sounds are muffled due to emphysema, and an accentuation of the second sound on the pulmonary artery is often determined due to pulmonary hypertension.

[ 40 ], [ 41 ], [ 42 ], [ 43 ], [ 44 ]

Examination of the digestive system

In severe chronic obstructive bronchitis, chronic gastritis with decreased secretory function is often detected, and gastric ulcer or duodenal ulcer may develop. In severe pulmonary emphysema, the liver is lowered, its diameter is normal; unlike congestive liver, it is painless and its size does not change after the use of diuretics.

Clinical manifestations of hypercapnia

With steady progression of bronchial obstruction, chronic hypercapnia may develop. Early clinical signs of hypercapnia are:

• sleep disturbance - insomnia, which may be accompanied by slight confusion;
• headache, which intensifies mainly at night (at this time of day, hypercapnia intensifies due to deterioration of ventilation);
• increased sweating;
• a sharp decrease in appetite;
• muscle twitching;
• large muscle tremors.

When studying the gas composition of the blood, an increase in the partial pressure of carbon dioxide is determined.

As hypercapnia continues to increase, confusion increases. The extreme manifestation of severe hypercapnia is hypercapnic hypoxemic coma, accompanied by seizures.

[ 45 ], [ 46 ], [ 47 ], [ 48 ], [ 49 ], [ 50 ]

Spirography

Impaired bronchial patency is indicated by a decrease in the forced vital capacity of the lungs (FVC) and the forced expiratory volume in the first second (FEV1).

FVC is the amount of air that can be exhaled with the fastest, forced exhalation. In healthy people, FVC exceeds 75% of VC. In bronchial obstruction, FVC is significantly reduced.

In the absence of bronchial obstruction, at least 70% of the air leaves the lungs in the first second of forced exhalation.

Usually FEV1 is calculated as a percentage of the vital capacity - the Tiffeneau index. It is normally 75-83%. In chronic obstructive bronchitis, the Tiffeneau index is significantly reduced. The prognosis for chronic obstructive bronchitis correlates with the FEV1 values. With an FEV1 of more than 1.25 l, the ten-year survival rate is about 50%; with an FEV1 of 1 l, the average life expectancy is 5 years; with an FEV1 of 0.5 l, patients rarely live more than 2 years. According to the recommendations of the European Respiratory Society (1995), the severity of chronic obstructive bronchitis is assessed taking into account the FEV1 value. Repeated determination of FEV1 is used to determine the progression of the disease. A decrease in FEV1 by more than 50 ml per year indicates disease progression.

Bronchial obstruction is characterized by a decrease in the maximum expiratory flow rate in the range of 25-75% of FVC (MEF25%), which is determined by analyzing the volume-flow curve.

MEF25-75 is less effort dependent than FEV1 and therefore serves as a more sensitive indicator of airflow obstruction in the early stages of the disease.

In chronic obstructive bronchitis, maximum ventilation of the lungs (MVL) is significantly reduced - the maximum amount of air ventilated by the lungs in 1 minute with deep and frequent breathing.

Normal values of MVL:

• men under 50 years old - 80-100 l/min;
• men over 50 years old - 50-80 l/min;
• women under 50 years old - 50-80 l/min;
• women over 50 years old - 45-70 l/min;

The appropriate maximum ventilation (IMV) is calculated using the formula:

DMVL = YEL x 35

Normally, MVL is 80-120% of DMVL. In COB, MVL is significantly reduced.

Pneumotachometry

Using pneumotachometry, the volumetric speed of the air stream during inhalation and exhalation is determined.

In men, the maximum expiratory flow rate is about 5-8 l/s, in women - 4-6 l/s. These indicators also depend on the patient's age. It is proposed to determine the proper maximum expiratory flow rate (PMEF).

DMSF = actual VC χ 1.2

When bronchial patency is impaired, the speed of the air flow during exhalation is significantly reduced.

Peak flowmetry

In recent years, the determination of the state of bronchial patency using peak flowmetry - measuring the maximum expiratory flow rate (l/min) - has become widespread.

In fact, peak flowmetry allows us to determine the peak expiratory flow rate (PEF), i.e. the maximum speed at which air can leave the airways during forced exhalation after a maximal inhalation.

The patient's PSV values are compared with normal values, which are calculated depending on the patient's height, gender and age.

In case of bronchial patency disorder, the PSV is significantly lower than normal. The value of PSV closely correlates with the values of forced expiratory volume in the first second.

Peak flowmetry is recommended to be performed not only in hospital, but also at home to monitor the state of bronchial patency (PSV is determined at different times of the day before and after taking bronchodilators).

For a more detailed characterization of the state of bronchial patency and the establishment of a reversible component of bronchial obstruction, tests with bronchodilators (anticholinergics and beta2-adrenergic stimulants) are used.

The berodual test (a combined aerosol preparation containing the anticholinergic ipratropium bromide and the beta2-adrenergic agonist fenoterol) allows for an objective assessment of both the adrenergic and cholinergic components of bronchial obstruction reversibility. In most patients, after inhalation of anticholinergics or beta2-adrenergic agonists, there is an increase in FVC. Bronchial obstruction is considered reversible when FVC increases by 15% or more after inhalation of the indicated drugs. Before prescribing treatment with bronchodilators, it is recommended to conduct the indicated pharmacological tests. The result of the inhalation test is assessed after 15 minutes.

Formulating a diagnosis

When formulating a diagnosis of chronic bronchitis, it is necessary to reflect the following characteristics of the disease as fully as possible:

• form of chronic bronchitis (obstructive, non-obstructive);
• clinical, laboratory and morphological characteristics of the inflammatory process in the bronchi (catarrhal, mucopurulent, purulent);
• phase of the disease (exacerbation, clinical remission);
• severity (according to ERS classification);
• presence of complications (pulmonary emphysema, respiratory failure, bronchiectasis, pulmonary arterial hyperthermia, chronic pulmonary heart disease, heart failure).

In addition, if possible, the infectious nature of the disease is deciphered, indicating the possible pathogen of the inflammatory process in the bronchi. In cases where it is possible to clearly determine the nosological affiliation of the disease (bronchitis), the term "COPD" can be omitted. For example:

• Chronic catarrhal simple (non-obstructive) bronchitis, exacerbation phase, caused by pneumococcus.
• Chronic non-obstructive purulent bronchitis, exacerbation phase.
• Chronic obstructive catarrhal bronchitis, pulmonary emphysema. Mild severity. Exacerbation phase. Respiratory failure of the first degree.

The term "COPD" is usually used when formulating a diagnosis in more severe cases (moderate and severe severity), when identifying the nosological affiliation of the disease causes certain difficulties, but there are clinical manifestations of broncho-obstructive syndrome and damage to the respiratory structures of the lungs. In this case, the term "COPD" is, if possible, deciphered by indicating the diseases that led to its development. For example:

• COPD: chronic obstructive catarrhal bronchitis, pulmonary emphysema. Moderate severity. Exacerbation phase. Respiratory failure grade II. Chronic pulmonary heart disease, compensated.
• COPD: chronic obstructive purulent bronchitis, obstructive pulmonary emphysema. Severe course. Phase of clinical remission. Respiratory failure grade II. Polycythemia. Chronic pulmonary heart disease, decompensated. Chronic heart failure II FC.
• COPD: bronchial asthma, chronic obstructive purulent bronchitis, pulmonary amphysema. Severe course. Exacerbation phase caused by the association of Haemophilus influenzae and Moraxella. Respiratory failure grade II. Chronic pulmonary heart disease, decompensated. Chronic heart failure II FC.