Primary Spontaneous Pneumothorax (PSP): Occurs without underlying lung disease. Classic patient is a tall, thin young male, often a smoker. Caused by rupture of apical subpleural blebs.
Secondary Spontaneous Pneumothorax (SSP): Occurs in patients with pre-existing lung disease. Most commonly associated with COPD; other causes include asthma, TB, cystic fibrosis, and interstitial lung disease.
Traumatic Pneumothorax: Caused by blunt or penetrating chest trauma (e.g., rib fracture).
Iatrogenic Pneumothorax: A subset of traumatic pneumothorax resulting from medical procedures like central line placement (especially subclavian), thoracentesis, lung biopsy, or positive-pressure ventilation (barotrauma).
Tension Pneumothorax: A life-threatening emergency where a one-way valve mechanism allows air to enter the pleural space but not exit. This leads to a progressive buildup of pressure.
Pathophysiology
Spontaneous pneumothorax: rupture of blebs and bullae → air moves into pleural space with increasing positive pressure → ipsilateral lung is compressed and collapses
Traumatic pneumothorax
Closed pneumothorax: air enters through a hole in the lung (e.g., following blunt trauma)
Open pneumothorax: air enters through a lesion in the chest wall (e.g., following penetrating trauma)
Air enters the pleural space on inspiration and leaks to the exterior on expiration.
Air shifts between the lungs.
Tension pneumothorax
Disrupted visceral pleura, parietal pleura, or tracheobronchial tree
One-way valve mechanism, in which air enters the pleural space on inspiration but cannot exit
Progressive accumulation of air in the pleural space and increasing positive pressure within the chest
Collapse of ipsilateral lung; compression of contralateral lung, trachea, heart, and superior vena cava; angulation of inferior vena cava
Impaired respiratory function, reduced venous return to the heart
Reduced cardiac output
Hypoxia and hemodynamic instability
Clinical features
Common Symptoms: Sudden onset of sharp, pleuritic, unilateral chest pain and dyspnea.
Physical Exam Findings:
Decreased or absent breath sounds on the affected side.
Hyperresonance to percussion.
Decreased tactile fremitus.
Asymmetric chest expansion.
Tension Pneumothorax Specifics: A medical emergency characterized by the above findings plus hemodynamic instability.
Marked respiratory distress, tachycardia, and hypotension (obstructive shock).
Tracheal deviation to the contralateral (unaffected) side.
In simple pneumothorax, the pressure in the damaged lung stops once it reaches atmospheric pressure. Because the pressure difference between the two sides remains less than or equal to 5 mmHg, the trachea does not shift. c
Jugular venous distention (JVD) due to compression of the superior vena cava, hypotension
Diagnostics
Differential diagnostics
Pneumomediastinum
Definition: presence of gas (usually air) in the mediastinum
Other: Inhalational drug use (e.g., crack cocaine), thoracic trauma, or esophageal rupture (Boerhaave syndrome).
Clinical Features
Symptoms: Sudden-onset retrosternal CP (may radiate to neck/back), SOB, and odynophagia.
Physical Exam:
Subcutaneous (SQ) emphysema: Palpable crepitus in the supraclavicular or cervical region (pathognomonic).
Hamman Sign: Precordial “crunching” or “clicking” sound synchronized with the heartbeat, best heard in the left lateral decubitus position.
Diagnosis
Initial: CXR (detects linear lucencies outlining the mediastinal structures, heart, or “continuous diaphragm sign”).
Confirmatory/Gold Standard: CT Chest (highest sensitivity; differentiates from PTX and identifies exact air distribution).
Key Labs: Usually normal; ↑ WBC may suggest Boerhaave or mediastinitis.
Esophagography: Indicated (Gastrografin swallow) if esophageal rupture (Boerhaave) is suspected based on history (e.g., violent retching).
Treatment
Small, stable, asymptomatic PSP: Observation and supplemental O2 (100% oxygen helps accelerate resorption of the air).
Large or symptomatic pneumothorax:
Needle aspiration (thoracocentesis) can be used for stable PSP.
Chest tube placement (thoracostomy) is the definitive initial treatment for large, secondary, or traumatic pneumothoraces.
Tension Pneumothorax:
Immediate needle decompression: A large-bore needle is inserted in the 2nd intercostal space at the midclavicular line (or 4th/5th intercostal space, anterior axillary line). This converts the tension pneumothorax into a simple pneumothorax.
Chest tube placement: Must be done after needle decompression for definitive management.
Recurrent Pneumothorax: Surgical intervention (VATS) with pleurodesis (chemical or mechanical scarring of the pleura) or pleurectomy is often indicated to prevent future episodes.
