Causes, Risk Factors, and Symptoms of Pneumothorax

Causes and Risk Factors

Pneumothorax is broadly divided into two types based on its cause: 'spontaneous pneumothorax,' which occurs on its own without trauma, and

'traumatic pneumothorax,' which is caused by trauma.

Classification of Pneumothorax

1. Spontaneous pneumothorax

· Primary spontaneous pneumothorax: Pneumothorax that occurs in healthy people without an existing lung disease

· Secondary spontaneous pneumothorax: Pneumothorax that occurs in people who already have a lung disease

· Neonatal spontaneous pneumothorax: Pneumothorax that occurs in newborns with certain conditions such as renal malformation, hyaline membrane disease, or meconium aspiration

· Catamenial spontaneous pneumothorax: Pneumothorax associated with menstruation in young women

2. Traumatic pneumothorax

1. Spontaneous pneumothorax

Spontaneous pneumothorax commonly occurs in tall, thin men in their late teens to 30s, and many of these patients have a history of smoking. In addition, although rare, familial spontaneous pneumothorax is known to occur in people with certain genes.

Factors in the development of spontaneous pneumothorax

1. Subpleural small blebs

Most cases of primary spontaneous pneumothorax occur when small blebs that develop just beneath the pleura covering the lungs rupture on their own, causing air to leak into the pleural cavity (thoracic cavity). A bleb is a small air pocket that forms between lung tissue and the pleura; it is an enlarged alveolus (1–2 cm in diameter) and usually develops at the very top of the lung (the apex).

It is thought that blebs form for the following two reasons.

· In tall, thin people, the upper part of the lungs grows faster than the pulmonary blood vessels during growth, leading to insufficient blood supply and the formation of blebs

· In tall people, the pressure inside the alveoli at the lung apex is relatively high, so blebs form

2. Pulmonary tuberculosis

In 2–3% of primary spontaneous pneumothorax cases, pulmonary tuberculosis is known to develop later.

In such patients, pulmonary tuberculosis is presumed to have contributed to the occurrence of pneumothorax.

3. Other factors

Spontaneous pneumothorax can also occur in the presence of lung diseases such as asthma, pneumonia, lung abscess, and whooping cough.

It can also occur in patients with Marfan syndrome, lung cancer, or congenital pulmonary cysts.

Meanwhile, in about 15–20% of pneumothorax patients, no special abnormality is found during surgery, and only scar tissue is observed at the lung apex.

2. Traumatic pneumothorax

Traumatic pneumothorax refers to a pneumothorax caused by external injury.

The most common cause of traumatic pneumothorax is a rib fracture caused by trauma that punctures and injures the adjacent lung. In addition, pneumothorax can occur when the chest is pierced by a sharp object such as a knife or after being shot. Pneumothorax can also occur during various procedures or treatments in the hospital.

Cases in which pneumothorax occurs during procedures or treatments

1. Subclavian vein catheter insertion 2) Thoracentesis 3) Mechanical ventilation/cardiopulmonary resuscitation

Types of traumatic pneumothorax

1. Simple pneumothorax

Air accumulates in the pleural cavity, showing a pattern similar to spontaneous pneumothorax.

2. Open pneumothorax

When the chest is injured by a knife, gun, or other object, the penetrating wound in the chest wall remains open, allowing air to move in and out of the pleural cavity through the wound when the patient breathes. In particular, if the wound is large, the lung can collapse completely, making it impossible for the patient to breathe properly, which can become a fatal condition.

3. A special form of pneumothorax: tension pneumothorax

Tension pneumothorax refers to a state in which air enters the pleural cavity when the patient inhales, but cannot escape when the patient exhales, causing pressure inside the pleural cavity to gradually rise.

Tension pneumothorax can occur in either spontaneous or traumatic pneumothorax. When tension pneumothorax occurs, the lung on the affected side of the pneumothorax collapses completely and presses on the opposite lung and even the heart. Therefore, severe shortness of breath, cyanosis, and low blood pressure can occur, which may become fatal, and immediate emergency treatment is required.

Symptoms

The two most important symptoms of pneumothorax are sudden chest pain and shortness of breath.

Chest pain is the most common symptom. It occurs independently of exercise and usually improves within 24 hours.

Shortness of breath tends to be more severe in people who already have lung disease or when the pneumothorax is larger.

When air accumulates in the pleural cavity, the lung collapses by the volume occupied by the air, so breathing movements cannot occur normally. In other words, even if the patient breathes hard, gas exchange in and out of the lungs does not occur properly, causing the patient to feel short of breath.

Many patients with spontaneous pneumothorax experience a sharp, stabbing pain at the moment the bleb first ruptures. This pain gradually changes into a dull, persistent pain. If the pneumothorax is not severe, it may feel like chest tightness, but as the pneumothorax becomes larger, shortness of breath gradually worsens.

Meanwhile, in tension pneumothorax, a large amount of air accumulates in the pleura and the pressure rises, pressing on the heart and the opposite lung, which causes severe shortness of breath, cyanosis, and low blood pressure.

In traumatic pneumothorax, diagnosis is relatively easy because there is a clear history of chest trauma or being stabbed with a knife. In the case of a large open pneumothorax, severe shortness of breath and low blood pressure may occur.

So far, we have explained the causes, risk factors, and symptoms of pneumothorax.

In the next part, we will look at the diagnosis and treatment of pneumothorax.

Source: Korea Disease Control and Prevention Agency, National Health Information Portal