anatomy

The Collapsed Lung: Types of Pneumothorax

Pneumothorax also known as collapsed lung occurs when air is trapped in the pleural space. Trapped air causes a loss of negative pressure in the pleural cavity, reduces surface tension, and induces the lungs to collapse. There are many different types of the collapsed lung or pneumothorax. Pneumothorax can be classified into spontaneous or traumatic. Spontaneous pneumothorax can be further classified into primary or secondary. Traumatic pneumothorax can be classified as closed or open. The most severe type of pneumothorax is the tension pneumothorax.

Pneumothorax is also known as a collapsed lung.

There are 3 types of Pneumothorax or collapsed lungs: 1) Spontaneous 2) Traumatic, and 3) Tension Pneumothorax.

Clinical Symptoms: chest pleuritic pain (sharp pain when breathing or taking a deep breath), shortness of breath (dyspnea), and asymmetrical chest expansion (only the affected side does not expand upon breathing). When percussing thorax, the affected side sounds hyper-resonant. That’s because of the excess air inside the chest.

Spontaneous vs Traumatic Pneumothorax

Spontaneous pneumothorax occurs spontaneously. There is no specific cause. In comparison, traumatic pneumothorax occurs because of chest trauma – blunt trauma, such as a rib fracture from car accident, or penetrating trauma such as a knife wound to the chest or neck.

Primary vs Secondary Spontaneous Pneumothorax

Primary spontaneous Pneumothorax

Usually tall thin males in their 20’s are the typical patients of primary spontaneous pneumothorax. Smoking can increase risk by 20-fold.

Primary spontaneous pneumothorax is a sudden rupture of subpleural apical blebs. What are subpleural apical blebs? These are small thin walled sacs of air in the lung, usually in the apex of top of the lung. When these apical blebs rupture, the air leaks into the pleural space in front of the lung and underneath the chest wall’s ribs.

Secondary Spontaneous Pneumothorax

Like all spontaneous pneumothoraxes, secondary spontaneous pneumothorax occurs spontaneously. There is no specific cause. However, unlike primary spontaneous pneumothorax, patients with secondary pneumothorax often have another underlying respiratory disease present, such as tuberculosis (TB), COPD, pneumonia, among many.

Traumatic Pneumothorax: Closed Pneumothorax vs Open Pneumothorax

There are 2 types of traumatic pneumothorax: 1. closed pneumothorax and 2. open pneumothorax. They sound exactly how they are. A closed pneumothorax follows blunt trauma and when there’s a hole in the lung. In a closed pneumothorax, the visceral pleura is damaged but the parietal pleura of the chest wall is not.

An open pneumothorax follows penetrating trauma, when there’s a hole in the chest wall. Literally, penetrating trauma like a gunshot wound or knife wound that opens a hole in the chest wall causes an open pneumothorax. Notice that blunt trauma does not cause a hole on the chest wall but rather internal injury damaging the visceral pleura covering the lung; a hole is created in the lungs causing air to leak out and thus a closed pneumothorax.

Closed Trauma Pneumothorax = Blunt Trauma = Damaged Visceral Pleura or Lung

Open Trauma Pneumothorax = Penetrating Trauma = Damaged Parietal (Peripheral) Pleura of Chest Wall

Pneumothorax vs Pleural Effusion

Pneumothorax is excess air that accumulates in the pleural space. This creates new unwanted positive pressure against the lungs which then collapse. Pneumothorax is thus also known as a “collapsed lung.”

Pleural effusion, on the other hand, is excess fluid that accumulates in the pleural space. Excess fluid can be pus, blood.

Pleural Cavity vs Pleural Space

Pleural Cavity is the pleural space. They are equivalent and refer to the space between the visceral pleura and parietal pleura. Basically the space between your chest wall and your lungs. Visceral pleura is a thin membrane that lines and surround your lungs. The parietal pleura covers the internal surface of your chest wall.

Parietal Pleura vs Visceral Pleura

Parietal Pleura lines the inside of the thoracic cavity or chest wall, while visceral pleura lines the outside of the lungs.

In between the parietal pleura and visceral pleura is the pleural space or pleural cavity.

The innervation of the parietal pleura and visceral pleura differs too. Parietal pleura is innervated by the phrenic and intercostal nerves, while the visceral pleura is innervated by the pulmonary plexus from the sympathetic trunk and vagus nerve.

Parietal pleura feels pressure, pain, and temperature. Visceral pleura only senses stretch, not touch, pain, or temperature.

Pneumothorax Important Terminology and Definitions

Iatrogenic = Caused by a treatment or procedure (Example: So if a penumothorax is iatrogenic, that means the lungs accidentally collapsed because of a treatment or procedure). Iatrogenic Pneumothorax is usually caused by mechanical ventilation such as with high PEEP (positive pressure),.

Tension Pneumothorax = a life-threatening form of pneumothorax, with symptoms of tracheal deviation, distended neck (jugular) veins, and hemodynamic instability. Can cause decreased venous return and decreased cardiac output. Immediate needle decompression and chest tube placement is needed.

Idiopathic Pneumothorax = Idiopathic means unknown origin, so unknown cause of pneumothorax. Idiopathic pneumothorax usually refers to primary spontaneous pneumothorax.

Increasing positive pressure causes pneumothorax.

Ipsilateral Lung = Lung on the same side; usually the collapsed affected lung

Contralateral Lung = Lung on the opposite side; the lung that is compressed against by the collapsed lung

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