Pneumothorax
Air trapped in the chest cavity outside the lung, causing the lung to partially or completely collapse, resulting in sudden chest pain and breathlessness.
Emergency Management: Tension pneumothorax. DO NOT wait for X-ray. Immediately perform emergent needle decompression using a large-bore (14-gauge) angiocatheter in the 2nd intercostal space at the mid-clavicular line, or 5th intercostal space at the mid-axillary line, followed by formal chest tube placement.
A pneumothorax is the presence of air or gas in the pleural cavity (the potential space between the visceral and parietal pleura), which impairs oxygenation and ventilation by impairing lung expansion.
Detailed Overview
Pneumothoraces are classified as spontaneous (primary or secondary) or traumatic (including iatrogenic). Primary spontaneous pneumothorax (PSP) typically occurs in tall, thin young men without underlying lung disease due to the rupture of subpleural apical blebs. Secondary spontaneous pneumothorax (SSP) occurs in patients with underlying lung pathology, most commonly COPD. A tension pneumothorax is a life-threatening medical emergency where a 'one-way valve' effect causes progressively increasing intrapleural pressure, leading to mediastinal shift, compression of the contralateral lung, and collapse of venous return to the heart.
Epidemiology & Demographics
Incidence of PSP is ~20 per 100,000 per year in men, and ~6 per 100,000 in women. Peak age for PSP is 20-30 years. SSP peaks in patients >60 years old.
Etiological Mechanism
Rupture of apical blebs (PSP). Rupture of emphysematous bullae, cystic fibrosis, or necrotizing pneumonia (SSP). Blunt/penetrating chest trauma, central line placement, or mechanical ventilation barotrauma (Traumatic).
Primary Causes
Spontaneous bleb rupture, penetrating trauma (stab wounds), iatrogenic (thoracentesis, subclavian vein catheterization, transbronchial biopsy), positive pressure ventilation.
The intrapleural pressure is normally negative (-5 cm H2O) relative to alveolar pressure, which keeps the lung expanded against the chest wall. When a defect occurs in the visceral pleura (e.g., ruptured bleb) or parietal pleura (e.g., stab wound), air flows down the pressure gradient into the pleural space. This equalizes pleural and alveolar pressure, eliminating the distending force and causing the elastic lung to collapse toward the hilum. This causes a V/Q mismatch and hypoxemia. In tension pneumothorax, the pleural defect acts as a one-way valve: air enters during inspiration but cannot exit during expiration. Intrapleural pressure rises rapidly above atmospheric pressure, compressing the superior and inferior vena cava, severely reducing venous return and cardiac output, leading to obstructive shock.
Diagnostic Criteria & Guidelines
Diagnosis is based on the visualization of a visceral pleural line lacking lung markings distally on chest imaging. Tension pneumothorax is a CLINICAL diagnosis and must be treated before obtaining imaging.
For small, asymptomatic PSP: Observation with 100% supplemental oxygen (accelerates nitrogen resorption from the pleural space by 4-fold) and repeat CXR in 4-6 hours. For large (>2 cm) or symptomatic PSP: Needle aspiration (e.g., 16-18G catheter in 2nd ICS mid-clavicular line) or small-bore (14F) chest tube (pigtail catheter) placement attached to a Heimlich valve or water seal.
Second-Line & Adjunctive Therapy
For SSP, failed aspiration, or trauma: Standard tube thoracostomy (20-28F chest tube) placed in the 4th/5th ICS mid-axillary line, connected to wall suction.
Surgical & Procedural Management
VATS (Video-Assisted Thoracoscopic Surgery) with blebectomy/bullectomy and mechanical pleurodesis (pleural abrasion) is indicated for recurrent PSP, bilateral pneumothorax, or incomplete lung expansion after 3-5 days of chest tube drainage.
Patient Counseling & Advice
Warn the patient about the high risk of recurrence (1 in 3 chance) and to immediately seek emergency care if sudden chest pain or shortness of breath returns. Emphasize that smoking is the largest modifiable risk factor.
Follow-Up & Monitoring Schedule
Outpatient follow-up with repeat chest X-ray in 2-4 weeks to ensure full lung re-expansion and no recurrence.
Preventive Strategies
Smoking cessation. Surgical pleurodesis for high-risk patients (e.g., airline pilots, deep-sea divers) even after a first episode.
Excellent with appropriate management. The primary issue is recurrence. Mortality from primary spontaneous pneumothorax is virtually zero, but secondary spontaneous pneumothorax carries a mortality of up to 10% due to poor baseline lung function.