Types of pneumothorax and their pathogenesis
Air can enter the pleural cavity in various ways. If entry occurs due to a simple rupture of lung tissue without communication with the external environment, a closed pneumothorax is formed.
A much greater danger is posed by tension (valvular) pneumothorax, which develops with a flap rupture of the lung. In this case, the damaged tissue acts as a one-way valve:
- During inspiration, the flap lifts, and a portion of air is sucked into the pleural cavity.
- During expiration, the flap presses against the opening, completely blocking the air from escaping back.
Such a mechanism leads to a rapid and continuous accumulation of air. Intra-thoracic pressure rises sharply. As a result, the lung on the affected side is compressed (collapses). Further pressure increases cause the mediastinal organs—the heart and large major vessels—to shift toward the healthy side, which ultimately leads to compression of the healthy lung as well.
Clinical presentation and diagnosis of pneumothorax
The condition of a patient with tension pneumothorax is assessed as severe and deteriorates immediately after sustaining the injury. The patient experiences severe dyspnea, chest pain, and profound agitation. The skin becomes pale with a characteristic bluish (cyanotic) tint. Cardiovascular manifestations include tachycardia, weak pulse volume, and a drop in blood pressure (hypotension).
Physical examination reveals the following signs:
- Inspection: the injured half of the chest visually lags behind during respiration, and the intercostal spaces may be smoothed out due to high intrapleural pressure.
- Percussion: a typical tympanic note is determined. The boundaries of cardiac dullness are shifted toward the healthy lung.
- Auscultation: respiratory sounds on the damaged side are sharply diminished or absent entirely.
The primary method for confirming the diagnosis is radiography. The image clearly visualizes air in the pleural cavity, the compressed (collapsed) lung, and mediastinal shift.
Emergency care consists of emergency pleural puncture followed by drainage. Puncture allows for the immediate evacuation of air and reduction of intrapleural pressure. A reliable sign of correct drainage in tension pneumothorax is the escape of air with a loud hiss.
Hemothorax
Unlike pneumothorax, hemothorax occurs in closed chest trauma accompanied by the rupture of intrathoracic blood vessels. Blood pours directly into the pleural cavity, leading not only to compression of the lung tissue but also to symptoms of acute blood loss.
Fluoroscopy and chest radiography are used to diagnose this condition (detecting fluid levels). Diagnostic pleural puncture, in which the surgeon obtains blood, definitively confirms the presence of blood.
Shock and wet lung syndromes
In severe injuries accompanied by massive blood loss, or in direct pulmonary contusion, a specific complication may develop — “shock lung”. Its pathogenesis is based on the process of intravascular coagulation within pulmonary vessels, which rapidly leads to acute respiratory failure (ARF). The patient is pale, cyanotic, and suffers from severe dyspnea, tachycardia, and hypotension. On auscultation, breath sounds are harsh or vesicular, yet no rales are auscultated. Radiography shows decreased tissue translucency and an enhanced pulmonary pattern. The mainstay of treatment is anticoagulant therapy.
An alternative scenario is the development of a “wet lung”. This syndrome is associated with bronchial gland hypersecretion against the background of impaired drainage function of the bronchial tree. A large amount of mucus accumulates in the bronchi. The patient's condition is extremely severe: a sense of fear and asphyxia arises, and dyspnea reaches 40–50 respiratory cycles per minute. Respiration becomes superficial, noisy, and bubbling. The main auscultatory sign of a “wet lung” is multiple moist rales of varying calibers.
For valvular pneumothorax, it is easy to remember the nipple principle: “On inspiration, the door is open — air entered. On expiration, it slammed shut — air is trapped.”
Class and exam questions
Because high pressure on the affected side shifts the mediastinal organs toward the healthy side, physically compressing the uninjured lung.
As a result, compression of the healthy lung occurs, which catastrophically worsens respiratory failure.
In "shock lung," rales are absent, and breathing is harsh. In "wet lung," multiple moist rales of varying calibers are auscultated, and the breathing itself is bubbling.
These differences are related to pathogenesis: in the first case, the problem lies in microcirculation (blood clotting), and in the second, in the accumulation of mucus in the bronchi.
A characteristic escape of air under pressure with a pronounced sound immediately after needle or drain insertion.
This indicates a high accumulation of air and an immediate relief of intrapleural pressure.
What else to study on this topic
- Technique of pleural puncture: access points
- Radiological signs of hemothorax and calculation of blood loss volume
- Principles of anticoagulant administration in pulmonary contusion
- Restoration of drainage function in “wet lung” syndrome
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