bubble_chart Overview

The pleural cavity is a sealed space that does not contain gas. The accumulation of air in the pleural cavity due to any cause is collectively referred to as pneumothorax. When alveoli and the visceral pleura spontaneously rupture on the basis of chronic lung disease, allowing air to enter the pleural cavity, it is called spontaneous pneumothorax, which is the most common clinical presentation. A large amount of pleural air causing severe lung compression and collapse can lead to respiratory and circulatory dysfunction. The main clinical manifestations of pneumothorax include sudden chest pain, chest tightness, and shortness of breath. In severe cases, patients may experience restlessness, cyanosis, cold sweating, or even shock.

bubble_chart Etiology

It is classified into the following types based on different causes.

1. Spontaneous pneumothorax is mostly caused by chronic lung diseases such as chronic bronchitis, lung qi swelling, bronchial asthma, fibrocavitary pulmonary subcutaneous nodules, etc., where alveoli and the visceral pleura rupture under certain triggers, allowing gas to enter the pleural cavity. Lung destruction due to sexually transmitted diseases, such as lung cancer, staphylococcal or anaerobic purulent pneumonia, or lung abscess, can infiltrate and erode into the pleural cavity, leading to pneumothorax, hemopneumothorax, or pyopneumothorax. Since these patients have clear underlying disease causes, they can be classified as secondary pneumothorax. Another group of patients, previously healthy with no acute or chronic lung diseases, develop pneumothorax of unknown cause and have a tendency for recurrence, termed idiopathic pneumothorax. In reality, this is often caused by the rupture of congenital subpleural bullae, commonly seen in tall, thin young adults. Recent findings suggest it may be accompanied by congenital deformities such as arachnodactyly, leading to the current belief that some cases of idiopathic pneumothorax may be a manifestation of Marfan syndrome.
2. Traumatic pneumothorax occurs due to accidents, such as penetrating or crush injuries to the chest wall. Cases where the chest wall has an open wound communicating with the external environment are called open pneumothorax, and hemopneumothorax is more likely when accompanied by rib fractures.
3. Iatrogenic pneumothorax may occur during procedures such as chest or back acupuncture, subclavian vein puncture, thoracentesis, or pleural and lung biopsies. Mechanical ventilation with excessive pressure can also cause alveolar and pleural rupture. Medical personnel should exercise caution when performing these procedures.
4. Artificial pneumothorax refers to the intentional injection of a controlled amount of gas into the pleural cavity for diagnostic or therapeutic purposes.
5. Other rare causes include menstruation-related pneumothorax, which occurs during menstruation. Approximately one-fourth of these cases involve the presence of uterine membrane in the pleura or diaphragm, termed endometriosis, which can lead to hemopneumothorax. Another one-fourth of cases involve small holes in the right diaphragm, allowing gas to enter the pleural cavity via the fallopian tubes and abdominal cavity. Spontaneous esophageal rupture can allow gas to enter the pleural cavity through a mediastinal pleural tear, often causing hydropneumothorax. Sudden transitions from high-pressure to low-pressure environments, such as rapid ascents during diving without proper precautions, can result in diver’s pneumothorax. These should all be categorized under spontaneous pneumothorax.

Clinically, spontaneous pneumothorax is the most common and is the focus of this chapter. Aside from underlying disease causes, most cases of spontaneous pneumothorax have triggering factors, including: (1) Cold fronts and temperature drops—clinical observations show a rapid increase in spontaneous pneumothorax incidence with sudden temperature drops, with over 60% occurring in winter; (2) Respiratory infections—especially in patients with chronic lung diseases like chronic bronchitis, lung qi swelling, or pneumoconiosis, respiratory infections, particularly those accompanied by severe coughing, can easily trigger pneumothorax; (3) Sudden increases in airway or intrapulmonary pressure—common triggers include lifting heavy objects, severe coughing, sneezing, breath-holding, shouting, laughing, or straining during bowel movements, all of which can abruptly raise airway and intrapulmonary pressure, leading to pneumothorax.

Surgical and autopsy findings confirm that spontaneous pneumothorax, whether secondary or idiopathic, often involves thin subpleural bullae at the lung margins, which serve as the foundation for pneumothorax. Under triggering factors such as cold air or inflammatory irritation, bronchospasm and increased airway resistance, or sudden rises in intrapulmonary pressure, can overinflate these bullae, increasing their tension. Severe coughing with glottal closure or rebound impact on already tense bullae can further elevate tension, causing the bullae and visceral pleura to rupture suddenly. This allows gas from the airways and alveoli to rapidly enter the pleural cavity, forming pneumothorax.

bubble_chart Type

According to the condition of the pleural membrane rupture and the pressure in the pleural cavity, it can be divided into the following types.

1. Closed pneumothorax: The pleural membrane rupture is small, and the amount of gas accumulated in the pleural cavity is relatively low. In most patients, the pleural cavity remains under negative pressure. When the lung is compressed and retracts, the rupture may self-seal in a short period due to serofibrinous exudation, preventing further gas from entering the pleural cavity. The existing gas can gradually be absorbed, allowing the lung to re-expand.
2. Open pneumothorax: This refers to a larger pleural membrane rupture that remains open and communicates with the bronchus. During inhalation and exhalation, gas moves in and out of the pleural cavity, disrupting the negative pressure in the pleural cavity. When pressure is measured, it often fluctuates around the zero point. After extracting a large amount of gas, the pressure may become negative, but it rises back to zero within minutes. The cause of this communication is often due to pleural adhesions pulling on the rupture, making it difficult to close.
3. Tension or high-pressure pneumothorax: This occurs when the pleural membrane rupture forms a valve-like obstruction. During inhalation, the valve opens, allowing gas to enter the pleural cavity, while during exhalation, the valve closes, similar to the mechanism of inflating a tire. Gas can only enter but not exit or exits very little, causing the pressure in the pleural cavity to rise rapidly, forming a high-pressure pneumothorax. When pressure is measured, it is consistently high and positive. If gas is rapidly extracted, the pressure may drop to negative but quickly rises back to positive. Due to the high tension, the lung is completely compressed, and the mediastinum is displaced, potentially compressing blood vessels and endangering life, requiring emergency treatment.

Additionally, pneumothorax can be classified based on anatomical morphology and the presence of fluid: (1) Common type: This is the typical and most common form of pneumothorax, where the lung is uniformly compressed, showing a symmetrical pneumothorax compression line from top to bottom. It is usually unilateral, though bilateral pneumothorax may occur simultaneously or sequentially in rare cases. (2) Localized pneumothorax: Due to pleural adhesions, the pleural cavity is partitioned, confining the gas to a specific area of the pleural cavity, also known as encapsulated pneumothorax, often related to pleural inflammation. (3) Multiloculated pneumothorax: Adhesions form within the pneumothorax cavity, dividing the gas into multiple small compartments. This is usually caused by untreated or improperly managed initial pneumothorax or recurrent episodes leading to multiple pleural adhesions. (4) Hydropneumothorax: This includes pyopneumothorax and hemopneumothorax. X-rays typically show a fluid level with gas above it in the lower part.

bubble_chart Clinical Manifestations

1. The clinical symptoms of pneumothorax depend on the type of pneumothorax, the speed of its development, the degree of lung compression, and the underlying lung disease.

   Typical spontaneous pneumothorax often presents with sudden chest pain, followed by irritative cough, chest tightness, shortness of breath, wheezing, difficulty lying flat, and a preference for lying on the unaffected side. If there is pre-existing extensive lung disease, symptoms may be significant even with a small amount of air accumulation.

   Tension pneumothorax, due to its rapid onset, large volume of air accumulation, severe lung compression, and mediastinal shift with compression of major blood vessels, often manifests as severe chest pain that may radiate to the shoulders, back, and forearms, accompanied by severe dyspnea, anxiety, forced upright posture, cyanosis, cold sweating, a sense of suffocation, and even respiratory failure, shock, and impaired consciousness.

   If pneumothorax develops slowly, with a small amount of air accumulation, or if the tear heals quickly, or if there is no or only grade I lung disease, symptoms may be minimal or only mild chest tightness, and pneumothorax may only be detected on X-ray examination.

2. The typical signs of pneumothorax include: fullness of the affected hemithorax, reduced respiratory movement; widened intercostal spaces, decreased vocal fremitus, tracheal deviation to the unaffected side; tympanic percussion note, cardiac displacement to the unaffected side; diminished or absent breath sounds, with compensatory hyperresonance, coarse sounds, and wheezing on the unaffected side, the latter possibly related to reflex bronchospasm. Additionally, a positive coin test is often present, where a coin or metal plate is placed on the anterior chest of the affected side and tapped with another coin, producing a metallic percussion sound heard on auscultation at the corresponding posterior site, which is an important and sensitive sign of pneumothorax. In cases of hydropneumothorax, tympany is noted in the upper part and dullness in the lower part, with possible splashing sounds. Signs may be subtle with small amounts of air accumulation.

bubble_chart Auxiliary Examination

In the analysis of blood qi aspects, PaO₂ and PaCO₂ may decrease.

X-ray examination is the most important method for diagnosing pneumothorax, as it can reveal the amount of accumulated air, the degree of lung compression, the type of pneumothorax, pleural adhesions, pleural effusion, mediastinal shift, and more. It also allows monitoring of lung re-expansion during treatment, making it an indispensable diagnostic tool. In typical pneumothorax cases, a translucent band of accumulated air can be observed in the outer zone, devoid of lung markings, while the inner zone shows increased density due to compressed lung tissue. A distinct curved boundary, known as the pneumothorax compression line, separates these two zones. In cases of massive pleural air accumulation, the lung tissue may collapse toward the hilum, forming a mass-like structure with an arc-shaped or lobulated outer edge, often indicative of tension pneumothorax. A hydropneumothorax typically presents with a classic air-fluid level. For minor air accumulation confined to the lung apex, the pneumothorax compression line may be indistinct, making it easy to misdiagnose as fistula disease if not carefully examined. Combining chest fluoroscopy to observe increased lung retraction density at the end of expiration can help identify the compression line. In cases of localized or multiloculated pneumothorax, a simple posteroanterior X-ray may be confused with lung qi cysts or bullae, necessitating observation from different angles for accurate diagnosis.

bubble_chart Diagnosis

1. Spontaneous pneumothorax often has a background of chronic lung disease and is usually triggered by certain factors.
2. Sudden onset of unilateral chest pain, followed by irritating cough, chest tightness, shortness of breath, and wheezing; in severe cases, the patient may assume an orthopneic position, exhibit cyanosis, profuse sweating, and even develop shock and impaired consciousness.
3. Typical signs of pneumothorax may be present.
4. X-ray examination revealing the pneumothorax compression line can confirm the diagnosis.

Patients with pre-existing severe pulmonary emphysema, cor pulmonale, or acute asthma attacks already have lung hyperinflation and dyspnea. When pneumothorax occurs, although symptoms worsen, the signs may not be obvious. Alternatively, in cases of bilateral pneumothorax, the lack of comparative signs between the two sides may lead to misdiagnosis as an exacerbation of the primary disease, without considering concurrent pneumothorax. Additionally, due to the severity of the condition and difficulty in moving the patient, timely X-ray examination may not be feasible, often resulting in misdiagnosis. Therefore, when such patients experience changes in their condition, vigilance for concurrent pneumothorax is warranted, and bedside X-ray examination should be arranged if possible.

bubble_chart Treatment Measures

1. Pneumothorax Therapy

If the patient's condition permits, a chest X-ray should first be performed to assess the volume of pneumothorax and the degree of lung compression. The intrapleural pressure should be measured using an artificial pneumothorax apparatus to determine the type of pneumothorax. Generally, if the lung is compressed by more than 20% and the intrapleural pressure is positive with dyspnea, pneumothorax drainage should be performed. There are various methods available, and the appropriate one can be selected based on the patient's condition.

Tension pneumothorax is a critical condition. Immediate drainage can be performed using a pneumothorax apparatus to measure pressure and aspirate air simultaneously, rapidly reducing the intrapleural pressure to equilibrium (zero) or negative pressure before further treatment. Alternatively, a large syringe connected to a three-way stopcock or rubber tube can be used for thoracentesis and air aspiration. Closed drainage can also be directly installed (method described later). In emergencies, a thick needle with a rubber finger cot (with a small slit) tied to its end can be inserted into the pleural cavity at the conventional pneumothorax puncture site to allow unidirectional air drainage. When a large amount of air is expelled and the pleural pressure drops to negative, the finger cot collapses, preventing external air from flowing back into the pleural cavity. This serves as a simple and effective temporary drainage method.

The treatment of open pneumothorax and further management of tension pneumothorax require the installation of closed thoracic drainage to ensure continuous and effective air removal, allowing the compressed lung to re-expand as quickly as possible. The method involves making a 2–3 cm transverse incision along the upper edge of the rib at the second intercostal space in the midclavicular line (the conventional pneumothorax puncture site) or the 4th–5th intercostal space in the anterior axillary line under routine disinfection and local anesthesia. A trocar is inserted into the pleural cavity, the stylet is removed, and a sterile rubber tube is advanced about 3–4 cm into the pleural cavity. The outer sheath is then withdrawn. Alternatively, after skin incision, blunt dissection is performed to reach the pleura, and the rubber tube is directly inserted into the pleural cavity using forceps to puncture the pleura. The forceps are then withdrawn, and the rubber tube remains in the pleural cavity, secured with sutures. Another rubber tube is connected to a water-seal bottle, with the tube submerged 1–2 cm underwater. When the intrapleural pressure exceeds this level, air is expelled through the water-seal bottle. A silicone tube is preferred for intrapleural drainage, with its tip cut into a duckbill shape and two side holes to prevent blockage and facilitate drainage. During closed drainage installation, ensure the skin incision is not too small to avoid subcutaneous emphysema. Monitor the drainage tube for patency and address any blockages promptly. If pneumothorax is accompanied by pleural effusion, the tube should be inserted one intercostal space above the fluid level as indicated by X-ray, using a double-bottle closed drainage system—the first bottle collects pleural fluid, and the second bottle drains air. After drainage, if symptoms improve, no air bubbles are observed, and X-ray confirms full lung re-expansion, the tube can be clamped for observation. If the lung remains well-expanded after 24 hours, the tube can be removed.

If the lung fails to re-expand after 2–3 days of closed drainage, continuous negative-pressure suction can be applied. This involves adding a pressure-regulating bottle connected to the suction device to the standard closed drainage system. The pressure-regulating tube should be submerged 8–12 cm underwater. When the suction negative pressure falls below -8 to -12 cm H₂O, room air enters the pressure-regulating bottle to prevent excessive negative pressure, avoiding complications such as lung tissue injury or re-expansion pulmonary edema. Continuous negative-pressure suction for 2–3 days usually allows pleural tears to heal. After lung re-expansion, the tube can be removed following standard closed drainage procedures (Figure 2-12-1).

For closed pneumothorax with a significant air volume, thoracentesis and air aspiration can be performed once or several times at the conventional pneumothorax puncture site (second intercostal space in the midclavicular line) using an artificial pneumothorax apparatus or a large syringe. The remaining small amount of air can be absorbed spontaneously. For localized pneumothorax, aspiration under X-ray guidance or based on X-ray localization is safer and more reliable.

2. Treatment of Complications

(1) Pneumomediastinum

Pneumomediastinum is primarily caused by high intrapleural pressure, so the key is prompt decompression. If a large volume of air accumulates in the mediastinum with organ compression symptoms, a transverse incision can be made at the suprasternal fossa for drainage. For mild cases without significant symptoms, rest and symptomatic treatment are sufficient, as the air will be absorbed spontaneously once the pneumothorax resolves.

(2) Pyopneumothorax and Hemopneumothorax

For patients with concurrent empyema, thorough drainage should be performed, and effective antibiotics should be selected based on the infecting bacteria, which can be used both systemically and locally. For cases that do not heal over a long period and develop into chronic empyema, surgery may be considered. Hemopneumothorax is often caused by the tearing of blood vessels in the pleural adhesion band; bleeding usually stops spontaneously after lung re-expansion. If the bleeding is severe, blood transfusion should be administered, and surgical ligation of the blood vessels may be necessary to stop the bleeding.

(3) Patients with bronchopleural fistula, or persistent pneumothorax that cannot be re-expanded after the above treatments, or recurrent pneumothorax in a short period, as well as those with giant bullae, may consider surgical treatment. If surgery is not suitable, pleural adhesion therapy can be used, which involves injecting sterile tetracycline or hypertonic glucose into the pleural cavity, or insufflating talc powder or kaolin to induce sterile pleuritis, thereby sealing the pleural cavity and preventing recurrence of pneumothorax.

3. Disease causes and symptomatic treatment

Patients with pneumothorax should rest in bed, preferably in a semi-recumbent position. For closed pneumothorax with lung compression <20%, if there are no obvious symptoms, air extraction may not be necessary, as rest often leads to spontaneous absorption within 1–2 weeks. However, patients with pre-existing impaired lung function may experience significant symptoms even with minimal air accumulation and should undergo air evacuation. To prevent secondary infection of pneumothorax, appropriate antibiotics such as penicillin (800,000 units, intramuscularly twice daily) may be administered. Patients with obvious dyspnea and hypoxia should receive oxygen therapy. Cough suppressants and sedatives may also be prescribed to facilitate rest. It is important to maintain bowel regularity to avoid straining. Underlying conditions should be actively treated.

bubble_chart Prognosis

Most cases of pneumothorax can be cured with active treatment. However, tension pneumothorax or cases with severe complications may be life-threatening if not treated promptly and properly. Recurrent pneumothorax can impair lung function.

bubble_chart Prevention

1. Actively prevent and treat chronic lung diseases that can cause pneumothorax.
2. Educate patients prone to pneumothorax to avoid lifting heavy objects, constipation, breath-holding, severe coughing, and other factors that may trigger pneumothorax.
3. For patients with recurrent idiopathic pneumothorax, carefully search for subpleural bullae and consider surgical resection.
4. Medical personnel should perform relevant examinations and treatments, such as acupuncture, thoracentesis, and lung biopsy, with caution. During mechanical ventilation, air pressure should be controlled to prevent complications like pneumothorax.

bubble_chart Complications

Spontaneous pneumothorax, especially when the pleural membrane tear does not heal quickly or treatment is inadequate, can easily lead to pleural effusion; prolonged non-healing may result in a bronchopleural fistula; severe pleural infection or pulmonary abscess rupturing into the pleural cavity can cause pyopneumothorax; tearing of pleural adhesions or cancerous infiltration and rupture can lead to hemopneumothorax; mediastinal emphysema is a more severe complication of pneumothorax, often caused by tension pneumothorax gas entering the pulmonary interstitium, traveling along vascular sheaths or peribronchial spaces through the hilum into the mediastinum, frequently complicating left-sided pneumothorax. Severe cases may lead to respiratory and circulatory failure due to compression of mediastinal organs, also known as mediastinal air tamponade syndrome. Common manifestations include subcutaneous emphysema in the neck and anterior chest, which may extend to the face, abdomen, and even the whole body, with a typical crepitus sensation. Sometimes, Hamman's sign may be present, characterized by a crunching or crackling sound synchronous with the heartbeat heard over the precordium or lower sternum, caused by the heart beating against air-filled mediastinal tissues. X-ray imaging reveals gas-filled lucent bands around the mediastinum, heart, and major blood vessels.

bubble_chart Differentiation

1. Bronchial asthma and obstructive lung qi mass: During an asthma attack or lung infection, symptoms such as chest tightness, shortness of breath, wheezing, and cyanosis often occur, along with lung hyperinflation, which may resemble pneumothorax. The differences include a history of long-term recurrent asthma or chronic cough, absence of sudden chest pain, and bilateral symmetrical changes in lung signs such as weakened vocal fremitus, hyperresonance, and diminished breath sounds, which distinguish it from pneumothorax. X-ray examination can provide a definitive differential diagnosis.
2. Pulmonary bullae: Particularly giant pulmonary bullae, may be accompanied by chest tightness and shortness of breath. If the bulla is located near the lung periphery, it may sometimes be misdiagnosed as pneumothorax on X-ray, even leading to iatrogenic pneumothorax due to mistaken puncture. Key differences from pneumothorax include the absence of sudden chest pain or acute dyspnea, lack of predisposing factors for pneumothorax, and X-ray findings showing a round or oval air cavity with a thin linear wall, adjacent lung tissue compressed toward the apex, diaphragmatic angle, or hilum, forming a concave arc, and often residual strands or vascular trabeculae within the cavity. These features distinguish it from pneumothorax.
3. Other conditions: Acute pulmonary embolism may present with sudden chest pain, dyspnea, and cyanosis, resembling pneumothorax symptoms, but chest X-ray and physical signs show no evidence of pneumothorax. Sudden chest pain radiating to the shoulder and arm, accompanied by dyspnea, cold sweating, or even shock, may mimic angina or acute myocardial infarction, but electrocardiogram and chest X-ray can easily differentiate these conditions.