Causes and mechanisms of development
There are several key factors triggering the development of the condition. Smoking is in first place. Toxic exposures (e.g., inhalation of occupational dust) and age-related involutional changes also play an important role. A separate mechanical factor is hyperinflation of alveoli due to a constant increase in expiratory pressure. This is characteristic of chronic bronchitis (due to hacking cough) or occupations associated with prolonged stress on the respiratory system, such as glassblowers and wind instrument musicians.
The dominant concept of pathogenesis is considered to be the protease-antiprotease imbalance theory. Normally, enzymes capable of breaking down proteins are held in check by special systems, the main one being $\alpha_1$-antitrypsin synthesized by the liver. If this balance is disrupted (due to a genetic deficiency of antiproteases or under the influence of tobacco smoke), effector cells—macrophages and neutrophils—begin to actively release destructive enzymes. Structural proteins of the alveolar walls become the targets of neutrophil elastase, cathepsins, and metalloproteinases.
Pathophysiology and morphological changes
Normally, the pulmonary acinus consists of respiratory bronchioles transitioning into alveolar ducts and the alveoli themselves. In the most common panacinar emphysema, the interalveolar septa thin out and are destroyed. Small cavities merge together, forming extensive pathological spaces.
The destruction of structural elements leads to functional failures:
- Expiratory collapse phenomenon. The lungs lose their tissue framework and elastic recoil, which is necessary to keep the airways open. As a result, during expiration, the lower airways dynamically narrow and collapse, hindering airflow.
- Gas exchange impairment. Damage to the alveolar-capillary membrane radically reduces the surface area of the respiratory membrane. This leads to a sharp drop in the diffusing capacity of the lungs.
Clinical presentation and physical examination
The clinical profile of the patient is based on the syndrome of increased pulmonary aeration. The main complaint is dyspnea. It appears in the early stages, progresses, and reduces exercise tolerance. Initially, dyspnea is expiratory in nature (difficult to exhale), but when heart failure joins in, it becomes mixed or inspiratory. The classic phenotype of such a patient is termed "pink puffer" (pink puffer): pronounced dyspnea is present, while cyanosis is initially absent.
Physical examination data:
- Inspection: Barrel chest, active participation of accessory muscles in the act of breathing.
- Palpation: Decreased chest excursion, diminished vocal fremitus.
- Percussion: Hyperresonant (box) sound, downward displacement of the lower borders of the lungs and decreased mobility. The area of absolute cardiac dullness disappears, replaced by the hyperresonant sound.
- Auscultation: Uniformly diminished ("soft" or vesicular) breathing, prolonged expiration, and wheezing due to bronchial obstruction.
Diagnostics and treatment principles
Radiography reveals horizontally oriented ribs, wide intercostal spaces, and increased radiolucency of the lung fields. However, this picture is typical for far-advanced stages. The earliest radiological sign is a decrease in the excursion of the lower lung margin.
Pulmonary function testing (PFT) reveals:
- Drop in vital capacity (VC).
- Decreased Tiffeneau index.
- Increase in residual volume ("air trapping" forms).
- Critical decrease in diffusing capacity.
Treatment begins with absolute smoking cessation. Pathogenetic therapy aims to combat bronchospasm, actively suppress infectious agents, and maintain hydration for sputum clearance. Rehabilitation includes physical exercise and postural drainage. As it progresses, chronic cor pulmonale develops (cor pulmonale). In such cases, oxygen therapy is indicated, and diuretics, e.g., spironolactone, are prescribed to combat systemic edema (right ventricular failure).
Briefly: answers to topical questions
What morphological types of pulmonary emphysema exist, other than panacinar?
In addition to panacinar, the following morphological types of pulmonary emphysema are distinguished by the zone of acinar involvement:
- Centriacinar — central (proximal) parts of the acinus are affected.
- Paraseptal — only the distal part of the acinus is altered.
- Irregular — characterized by uneven involvement of the acinus.
Also, based on the morphological principle, other types are distinguished:
- Chronic obstructive
- Chronic focal
- Perifocal (scarring)
- Vicarious (compensatory)
- Senile
- Interstitial
- Idiopathic
A separate form is bullous emphysema, which is characterized by areas of destruction greater than 1 cm in size.
How does the "pink puffer" phenotype clinically differ from the "blue bloater"?
The "pink puffer" phenotype (emphysematous type) differs from the "blue bloater" phenotype (bronchitic type) by the absence of cyanosis, predominance of dyspnea, and later development of complications.
| Sign | "Pink puffer" | "Blue bloater" |
|---|---|---|
| Appearance | Asthenic build, cyanosis absent | Cyanosis and peripheral edema are more commonly observed |
| Respiration | Pronounced dyspnea, patients "puff" for a long time | Dry wheezes, prolonged expiration |
| Cough | Appears after the onset of dyspnea | Symptoms develop 5–10 years earlier |
| Complications | Chronic cor pulmonale develops late | Pulmonary arterial hypertension and cor pulmonale develop earlier |
The phenotype of a patient with isolated emphysema is described as a "pink puffer". Easy to remember: the patient is "pink" because they lack marked cyanosis (unlike the bronchitic type), and a "puffer" due to severe dyspnea and active work of accessory muscles.
Class and exam questions
Why is exhalation specifically impaired in emphysema?
Due to the loss of the elastic framework of the lung tissue, small airways lose support and collapse during expiration (expiratory collapse phenomenon), creating a mechanical barrier to airflow.
What percussion note is characteristic of this condition?
A hyperresonant (box) sound is determined over the entire surface of the chest, which arises due to the increased aeration of destroyed lung tissue.
How does emphysema affect the cardiac borders upon percussion?
The area of absolute cardiac dullness decreases or completely disappears. The hyperinflated lungs cover the heart anteriorly, and a hyperresonant sound also begins to be determined over this area.
What else to study on this topic
- Clinical and ECG signs of chronic cor pulmonale development.
- Detailed analysis of the protease-antiprotease theory and the role of α1-antitrypsin deficiency.
- Dynamics of PFT parameters (Tiffeneau index, VC, residual volume) at different stages.
- Morphological differences of panacinar emphysema from other forms.
- The role of postural drainage and pulmonary rehabilitation.
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