Bullous emphysema is a local change in lung tissue characterized by the destruction of alveolar septa and the formation of air cysts with a diameter of more than 1 cm (bull). With an uncomplicated course of bullous emphysema, symptoms may be absent until the occurrence of spontaneous pneumothorax. Diagnostic confirmation of bullous emphysema is achieved using radiography, high-resolution CT, scintigraphy, thoracoscopy. With an asymptomatic form, dynamic observation is possible; in case of progressive or complicated course of bullous lung disease, surgical treatment is performed (bullectomy, segmentectomy, lobectomy).
Bullous emphysema causes
To date, there are a number of theories explaining the genesis of bullous disease (mechanical, vascular, infectious, obstructive, genetic, enzymatic). Adherents of the mechanical theory suggest that the horizontal arrangement of the I-II ribs in some people leads to traumatization of the apex of the lung, causing the development of apical bullous emphysema. There is also an opinion that bullae are a consequence of pulmonary ischemia, i.e. a vascular component is involved in the development of bullous disease.
The infectious theory connects the origin of bullous emphysema with nonspecific inflammatory processes, mainly viral infections of the respiratory tract. In this case, local bullous changes are a direct consequence of obstructive bronchiolitis, accompanied by overgrowth of lung areas. This concept is confirmed by the fact that relapses of spontaneous pneumothorax often occur during epidemics of influenza and adenovirus infection.
Local bullous emphysema may occur in the area of the apex of the lung after tuberculosis. Based on the observations, a theory has been put forward about the genetic conditionality of bullous emphysema. The families in which this disease was traced in representatives of several generations are described.
Morphological changes in the lungs (bullae) may have either congenital or acquired origin. Congenital bullae are formed with a deficiency of the elastase inhibitor – a1-antitrypsin, which results in enzymatic destruction of lung tissue. A high probability of developing bullous emphysema is noted in Marfan syndrome, Ehlers–Danlos syndrome and other forms of connective tissue dysplasia.
Acquired bullae in most cases develop against the background of existing emphysematous lung changes and pneumosclerosis. 90% of patients with bullous emphysema have a history of long-term smoking experience (10-20 years with daily smoking of more than 20 cigarettes). It has been proven that even passive smoking increases the likelihood of developing bullous disease by 10-43%. Other known risk factors are air pollution by aerogenic pollutants, flue gases, volatile chemical compounds, etc.; frequent respiratory diseases, bronchial hyperreactivity, immune status disorders, male gender, etc.
The bull formation process goes through two successive stages. At the first stage, bronchial obstruction, limited cicatricial-sclerotic processes and pleural fusion create a valve mechanism that increases pressure in small bronchi and promotes the formation of air bubbles with the preservation of interalveolar septa.
At the second stage, progressive stretching of the air cavities occurs. With a deficiency of a1-antitrypsin, the activity of neutrophil elastase increases, causing the splitting of elastic fibers and the destruction of alveolar tissue. Further expansion of the air cavities due to the mechanism of collateral respiration leads to expiratory collapse of the bronchi. The area of the respiratory surface is reduced, respiratory failure develops.
In relation to the parenchyma of the lung , there are three types of bulls:
- the bulls are located extraparenchymatous and are connected to the lung by means of a narrow leg;
- the bulls are located on the surface of the lung and are connected to it by a wide base;
- the bulls are located intraparenchymatous, in the thickness of the lung tissue.
In addition, bulls can be solitary and multiple, one– and two-sided, tense and non-tense. According to the prevalence in the lung, localized (within 1-2 segments) and generalized (with a lesion of more than 2 segments) bullous emphysema are differentiated. Depending on the size, the bulls can be small (up to 1 cm in diameter), medium (1-5 cm), large (5-10 cm) and giant (10-15 cm in diameter). Bullae can be located both in the unchanged lung and in the lungs affected by diffuse emphysema.
According to the clinical course , bullous emphysema is classified:
- asymptomatic (no clinical manifestations)
- with clinical manifestations (shortness of breath, cough, chest pain)
- complicated (recurrent pneumothorax, hydropneumothorax, hemopneumothorax, pulmonary pleural fistula, hemoptysis, rigid lung, mediastinal emphysema, chronic respiratory failure).
Bullous emphysema symptoms
Patients with bullous lung disease often have an asthenic constitution, vegetative-vascular disorders, spinal curvature, chest deformity, muscle hypotrophy. The clinical picture of bullous emphysema is determined mainly by its complications, therefore, for a long period of time, the disease does not manifest itself in any way. Despite the fact that the bullously altered areas of lung tissue do not participate in gas exchange, the compensatory capabilities of the lungs remain at a high level for a long time. If the bulls reach gigantic sizes, they can squeeze the functioning areas of the lung, causing a violation of the respiratory function. Signs of respiratory insufficiency can be determined in patients with multiple, bilateral bullae, as well as bullous disease occurring against the background of diffuse emphysema of the lungs.
The most common complication of bullous disease is recurrent pneumothorax. The mechanism of its occurrence is most often caused by an increase in intrapulmonary pressure in the bulls due to physical exertion, lifting weights, coughing, straining. This leads to the rupture of the thin wall of the air cavity with the release of air into the pleural cavity and the development of lung collapse. Signs of spontaneous pneumothorax are sharp pains in the chest with irradiation to the neck, collarbone, arm; shortness of breath, inability to take a deep breath, paroxysmal cough, forced position. Objective examination reveals tachypnea, tachycardia, expansion of intercostal spaces, restriction of respiratory excursions. Subcutaneous emphysema may occur with spread to the face, neck, trunk, scrotum.
Diagnosis of bullous emphysema is based on clinical, functional and radiological data. The patient is supervised by a pulmonologist, and with the development of complications – by a thoracic surgeon. Lung x-ray is not always effective in detecting bullous emphysema. At the same time, the possibilities of radiation diagnostics are significantly expanded by the introduction of high-resolution CT into practice. On tomograms, bulls are defined as thin-walled cavities with clear and even contours. In case of a doubtful diagnosis, diagnostic thoracoscopy allows you to verify the presence of bull.
Ventilation-perfusion scintigraphy of the lungs allows us to assess the ratio of functioning and ventilation-free lung tissue, which is extremely important for planning surgical intervention. In order to determine the degree of pulmonary insufficiency, the function of external respiration is investigated. The criterion for emphysematous changes is a decrease in FEV1, Tiffno and VC samples; an increase in total lung volume and FRC (functional residual capacity).
Bullous emphysema treatment
Patients with an asymptomatic course of bullous emphysema and the first episode of spontaneous pneumothorax should be monitored. They are advised to avoid physical exertion, infectious diseases. Methods of physical rehabilitation, metabolic therapy, and physiotherapy can prevent the progression of bullous emphysema. When spontaneous pneumothorax develops, an immediate pleural puncture or drainage of the pleural cavity is indicated in order to straighten the lung.
In the case of an increase in signs of respiratory failure, an increase in the size of the cavity (with control radiography or CT of the lungs), the occurrence of recurrent pneumothorax, inefficiency of drainage procedures for straightening the lung, the question of surgical treatment of bullous emphysema is raised. Depending on the severity of the changes, localization and size of the bulls, their removal can be performed by bullectomy, anatomical resections. Various operations for bullous disease can be performed in an open way or using video endoscopic technologies (thoracoscopic lung resection). In order to prevent the recurrence of spontaneous pneumothorax, pleurodesis (treatment of the pleural cavity with iodized talc, laser or diathermocoagulation) or pleurectomy can be performed.
Prognosis and prevention
Without surgical treatment, bullous disease is accompanied by recurrent pneumothorax, which limits the patient’s domestic and professional activity. After undergoing surgical treatment, all manifestations of the disease usually disappear. Prevention of bullous disease is generally similar to measures to prevent emphysema of the lungs. It is necessary to unconditionally exclude smoking (including exposure to tobacco smoke on children and non-smokers), contact with harmful industrial and environmental factors, prevention of respiratory infections. Patients with diagnosed bullous emphysema should avoid situations that provoke a rupture of the bull.
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