What Causes Spontaneous Pneumothorax?

Spontaneous pneumothorax refers to the rupture of lung tissue and visceral pleura due to lung diseases, or the rupture of bullae and fine emphysema near the surface of the lungs, allowing air in the lungs and bronchi to escape into the pleural cavity. More common in young men or men with chronic bronchitis, emphysema, tuberculosis. This disease is one of the pulmonary emergency cases, severe cases can be life threatening, timely treatment can be cured.

Basic Information

Visiting department

Respiratory Medicine

Multiple groups

Young men or men with chronic bronchitis, emphysema, or tuberculosis

Common causes

Pulmonary disease causes rupture of lung tissue and visceral pleura, or spontaneous rupture of bullae, subtle emphysema, etc.

Common symptoms

Dyspnea, chest pain, irritating cough, etc.

Spontaneous pneumothorax etiology

The pleural cavity is a closed cavity between the visceral and parietal pleura. Due to the elastic retraction force of the lung, it is a negative pressure cavity [-0.29 to 0.49kPa (-3.5cmH ₂ O)]. When a certain cause causes a sharp increase in the alveolar pressure, the damaged lung-pleura ruptures, the pleural cavity communicates with the atmosphere, and the air enters the chest cavity to form spontaneous pneumothorax. Spontaneous pneumothorax is mostly secondary. In some patients, due to lung retraction during expiration, or due to serous exudates, the visceral pleura is closed by itself, and no more air leaks into the pleural cavity, resulting in closed (simple) pneumothorax. Parietal pleura adhesion. When pneumothorax is formed, the lung tissue ruptures fistula or bronchopleural fistula cannot be closed with the compression of the lungs, causing the fistula to continue to open and the thoracic pressure to be close to zero. Some patients form a valve-like valve due to bronchoconstriction and semi-obstruction, so that air enters the chest cavity during inhalation and remains here during exhalation. The chest pressure can exceed 1.96kPa (20cmH ₂ O), becoming "tensile (high pressure) "Pneumothorax"; due to the above reasons, spontaneous pneumothorax is often difficult to heal, and more pneumothorax and localized pneumothorax are more common, while simple closed pneumothorax is rare.

Spontaneous pneumothorax clinical manifestations

Dyspnea

Patients with pneumothorax have dyspnea. The severity of pneumothorax is related to the process of the attack, the degree of compression of the lungs, and the original state of lung function. In young patients with normal respiratory function, there is no obvious difficulty in breathing. Even if the lungs are compressed> 80%, they can only feel a little tight when they are active. In elderly patients with chronic obstructive emphysema, the lungs are Mild compression can cause significant breathing difficulties. Pneumothorax in acute attacks may have more obvious symptoms; pneumothorax in chronic attacks may have compensatory swelling of the lungs on the contralateral side, and clinical symptoms may be mild.

Chest pain

Pneumothorax often occurs with sharp tingling and cutting pain, which has nothing to do with the sudden rupture of the bullae and the degree of lung compression, and may be related to increased pressure in the pleural cavity and stretched parietal pleura. The pain is not fixed, it can be confined to the chest, and it can also radiate to the shoulders, back and upper abdomen. In the presence of significant mediastinal emphysema, persistent retrosternal pain can occur. Pain is the most common complaint of patients with pneumothorax and may be the only symptom in mild pneumothorax.

3. Irritating cough

Spontaneous pneumothorax occasionally has an irritating cough.

4. Other symptoms

When pneumothorax is combined with blood pneumothorax, if the amount of bleeding is large, the patient will have palpitations, low blood pressure, and cold limbs.

Spontaneous pneumothorax

Arterial blood gas examination

Hypoxemia occurs in patients with pneumothorax in the acute phase due to ineffective perfusion of collapsed lung tissue, causing right-to-left shunts. Hypoxemia can be relieved because the blood flow of the collapsed lung is reduced in the later stage. Hypoxemia generally occurs in young people with pneumothorax when the lungs are compressed by 20% to 30%. Spontaneous pneumothorax often occurs when mild pulmonary compression occurs.

2. Laboratory inspection

Thoracic gas analysis: The use of three indicators of thoracic gas PaO ₂ , PaCO ₂ and PaO ₂ / PaCO ₂ ratio has certain significance for judging the type of pneumothorax. In the chest of closed pneumothorax, PaO ₂ 5.33kPa (40mmHg), PaCO ₂ often> 5.33kPa, PaO ₂ / PaCO ₂ > 1; Open pneumothorax PaO ₂ often> 13.33kPa (100mmHg), PaCO ₂ <5.33kPa, PaO ₂ / PaCO ₂ <0.4; tension-type pneumothorax PaO _{2 is} often> 5.33kPa, PaCO ₂ <5.33kPa, PaO ₂ / PaCO ₂ > 0.4 but <1.

3 Film degree exam

(1) X-ray examination is the most reliable method for diagnosing pneumothorax. It can show the degree of lung atrophy, the presence or absence of pleural adhesions, mediastinal displacement, and pleural effusion. Pneumothorax has increased transparency, no lung texture, lung atrophy in the hilar region, and clear thin strips of the lung edge at the junction with the pneumothorax. Site, so that the apical tissue of the lungs is pressed toward the hilum; if there is fluid pneumothorax, see the fluid level.

(2) CT examination is more sensitive to the diagnosis of a small amount of gas in the chest cavity. For patients with recurrent pneumothorax and chronic pneumothorax, observe whether there are lesions in the lungs that cause pneumothorax, such as bullae, pleural band adhesions, the lungs are stretched, and the gap is not easy to close. Pneumothorax basically manifests as a very low-density gas shadow in the pleural cavity, accompanied by varying degrees of compression and atrophy of the lung tissue.

(3) Pleural angiography This method can clarify the condition of the pleura surface, and it is easy to determine the cause of pneumothorax. When the compressed area of the lung is between 30% and 40%, radiography is appropriate. The bullae appear as single or multiple cystic low-density shadows within the contour of the lung lobe; the pleural fissure appears as a bubbling spray phenomenon, especially when the patient coughs. This sign is more pronounced due to increased intrapulmonary pressure.

4 Thoracoscopy

The cause of pneumothorax can be easily found, the operation is flexible, and it can reach interlobular fissures, apex of lungs, hilum, and almost no blind spots. Observe the visceral pleura for cracks, bullae under the pleura, and adhesions in the chest .

Spontaneous pneumothorax diagnosis

It is not difficult to diagnose by combining X-ray and CT based on clinical manifestations.

Differential diagnosis of spontaneous pneumothorax

Bullae

Pneumothorax with repeated attacks, due to adhesions in the chest, pneumothorax is easy to form a limited package. At this time, it is easy to be confused with tension bullae on X-ray chest radiographs. Pneumothorax often has a history of sudden onset, and tension bullae is repetitive chest tightness for a long time. On the X-ray bust, a thin pulmonary bullae edge line can be seen at the chest wall edge, especially at the costal corner. It is important to distinguish between pneumothorax and tension bullae. Misdiagnosis of tension bullae as pneumothorax and placement of a pleural drainage tube can easily cause severe pathophysiological changes.

2. Bronchial rupture

It should be said that bronchial rupture is one of the causes of traumatic tension pneumothorax. Bronchial rupture often has a history of traumatic chest injury. Trauma is characterized by a sudden stop during accelerated exercise, tension pneumothorax caused by bronchial rupture, and thoracic drainage tubes often have continuous outgassing. "Lung drooping" can be seen on X-ray busts "Symptoms", that is, the collapsed upper edge of the lung is lower than the hilum level, and the general cause of pneumothorax, lung collapse is toward the hilum.

3. Acute pulmonary embolism

Clinically, there may be symptoms such as dyspnea, and often accompanied by low fever, hemoptysis, shock, and increased white blood cell count. Generally, there is a history of repeated venous thrombosis of the lower limbs or a history of long-term bed rest. X-ray busts have no pneumothorax signs.

4. Other symptoms such as chest pain and dyspnea

Clinically, it should be distinguished from bronchial asthma, obstructive emphysema, myocardial infarction, pleurisy, and acute abdomen.

Spontaneous pneumothorax treatment

When the volume of closed pneumothorax is less than 20% of the volume of the thoracic cavity on the side, it is not necessary to pump air, and it can be absorbed by itself within 2 weeks. A large number of pneumothorax must be performed with pleural cavity puncture to exhaust the accumulation of gas, or closed chest drainage to reduce the pressure of accumulated gas on the lungs and the mediastinum, promote the early expansion of the lungs, and use antibiotics to prevent infection.