気胸I：概要

When air enters the pleural space between the chest wall and lungs, it disrupts the negative pressure essential for lung inflation. This loss of negative pressure causes the lung to collapse either partially or completely, impairing gas exchange and oxygen delivery to the body.

Spontaneous pneumothorax occurs when tiny blebs, or air-filled sacs, on the lung surface rupture without apparent injury. Risk factors include underlying lung diseases such as COPD, emphysema, cystic fibrosis, and pneumonia, as well as smoking, being tall and lean, and previous pneumothorax episodes.

Traumatic pneumothorax results from physical chest trauma or penetrating injuries that puncture the lung, such as rib fractures or stab wounds. Iatrogenic pneumothorax occurs when the lung is inadvertently punctured during medical procedures like lung biopsy, needle aspiration, or central venous line insertion.

Tension pneumothorax creates a one-way valve mechanism where air enters the pleural space but cannot escape, building pressure with each breath. This pressure displaces vital structures like the heart and trachea toward the unaffected side, impairing heart function, blood flow, and oxygen supply, potentially causing severe oxygen depletion.

Mediastinal shift is the displacement of vital structures, including the heart and trachea, toward the unaffected side. This occurs in tension pneumothorax when trapped air builds pressure in the pleural space, compressing the mediastinum and compromising cardiovascular and respiratory function.

Iatrogenic pneumothorax can result from lung biopsy, needle aspiration, central venous line insertion, subclavian catheter insertion, pleural biopsy, and transbronchial lung biopsy. These procedures carry risk when the needle or instrument inadvertently punctures lung tissue, allowing air to enter the pleural space.

Pneumothorax is one of several pleural disorders affecting the space between the lung and chest wall. Understanding pleural disorders types and brief description helps clinicians recognize how pneumothorax compares to conditions like pleural effusion, where fluid rather than air accumulates in the pleural space.