Abstract

A pneumothorax develops when air as the result of disease or injury enters the pleural space, resulting in the loss of negative pressure between the two pleural membranes. This loss of negative pressure leads to the partial or complete collapse of the lung. Pneumothorax is classified as spontaneous (e.g., by rupture of a subpleural bleb or diseased lung), traumatic, or iatrogenic. Each type can lead to a tension pneumothorax, which is a life-threatening variant of pneumothorax. Patients with pneumothorax present with sudden-onset dyspnea, ipsilateral chest pain, diminished breath sounds, and hyperresonant percussion on the affected side. A tension pneumothorax additionally presents with distended neck veins, tracheal deviation, and hemodynamic instability. Both should be suspected on clinical evaluation. While a tension pneumothorax requires immediate chest decompression, a chest x-ray may be considered to confirm the diagnosis in a stable patient. Small pneumothoraces may resorb spontaneously, but treatment of larger defects usually requires placement of a chest tube to re-establish the negative pressure within the pleural space.

Epidemiology

Primary spontaneous pneumothorax
- Sex: ♂ > ♀ (approx. 6:1)
- Peak incidence: 20–30 years
Secondary spontaneous pneumothorax
- Sex: ♂ > ♀ (approx. 3:1)
- Peak incidence: 60–65 years

References:^[1]

Epidemiological data refers to the US, unless otherwise specified.

Definition

A pneumothorax is a collection of air within the pleural space in between the lung (visceral pleura) and the chest wall (parietal pleura) that can lead to partial or complete pulmonary collapse.
Spontaneous pneumothorax: spontaneously occurring pneumothorax
- Primary spontaneous pneumothorax: occurs in patients without clinically apparent underlying lung disease
- Secondary spontaneous pneumothorax: pneumothorax occurs as a complication of underlying lung disease
Tension pneumothorax: life-threatening variant of pneumothorax characterized by progressively increasing pressures within the chest and cardiorespiratory compromise

References:^[1]

Etiology

Spontaneous pneumothorax
- Primary (idiopathic or simple pneumothorax)
  - Ruptured subpleural apical blebs
  - Risk factors
    - Family history
    - Male gender
    - Asthenic body habitus (slim, tall stature) (e.g., in Marfan syndrome)
    - Smoking: 90% of cases; up to 20-fold increase in risk (risk increases with cumulative number of cigarettes smoked)
    - Homocystinuria
- Secondary (pneumothorax as a complication of underlying lung disease)
  - Catamenial pneumothorax (extremely rare; thoracic endometriosis)
  - Pulmonary tuberculosis
  - Cystic fibrosis → bronchiectasis with obstructive emphysema and bleb or cyst rupture
  - Pneumocystis pneumonia → alveolitis, rupture of a cavity
  - COPD (smoking) → rupture of bullae in emphysema
Traumatic pneumothorax: blunt (e.g., motor vehicle accident with impact of thorax onto the steering wheel or rib fracture) or penetrating (e.g., gunshot) injury
Iatrogenic pneumothorax: Mechanical ventilation (Mechanical ventilation with high PEEP may result in barotrauma); , thoracocentesis; , central venous catheter placement, or bronchoscopy

A tension pneumothorax may occur with any of the above-mentioned etiologies!References:^[1]

Pathophysiology

Increased intrapleural pressure → alveolar collapse → decreased V/Q ratio and increased right-to-left shunting
Spontaneous pneumothorax: rupture of blebs and bullae → air moves into pleural space with increasing positive pressure; → ipsilateral lung is compressed and collapses →
- Rim pneumothorax: complete uncoupling of the pleura from the chest wall
- Apical pneumothorax: apical collection of air
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 → 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 and compression of contralateral lung, trachea, heart, and superior vena cava → impaired respiratory function, reduced venous return to the heart and reduced cardiac output → hypoxia and hemodynamic instability

References:^[2]

Clinical features

Clinical features vary from asymptomatic to cardiopulmonary compromise

Sudden, severe, and/or stabbing, ipsilateral pleuritic chest pain and dyspnea
Reduced, or absent breath sounds, hyperresonant percussion, decreased fremitus on the ipsilateral side
Subcutaneous emphysema
Additionally in tension pneumothorax:
- Severe acute respiratory distress: cyanosis, restlessness, diaphoresis
- Reduced chest expansion on the ipsilateral side
- Distended neck veins and hemodynamic instability; (tachycardia, hypotension, pulsus paradoxus)
- Secondary injuries (e.g., open or closed wounds)

P-THORAX: Pleuritic pain, Tracheal deviation, Hyperresonance, Onset sudden, Reduced breath sounds (and dyspnea), Absent fremitus, X-rays show collapse.References:^[1]^[3]

Diagnostics

General

Suspected pneumothorax is confirmed by chest x-ray.
- Immediate x-ray or an extended focused assessment with sonography for trauma (eFAST) in adults with severe respiratory compromise and children
CT may provide detailed information about the underlying cause (e.g., bullae in spontaneous pneumothorax).
Tension pneumothorax is primarily a clinical diagnosis and prolonged diagnostic studies should be avoided to initiate immediate treatment.

Diagnostic tests

Arterial blood gas analysis (ABG) to detect respiratory acidosis
Chest x-ray (confirmatory test)
- Ideally in two projections (PA and lateral), in supine and upright position
- Chest x-rays are often performed in expiration because it is believed that this allows better detection of small pneumothoraces.
  - Ipsilateral pleural line with reduced/absent lung markings
  - Sudden change in radiolucency
  - Deep sulcus sign: dark and deep costophrenic angle on the affected side
  - If pulmonary disease is present: airway or parenchymal lesions
  - Additional features in tension pneumothorax:
    - Ipsilateral diaphragmatic flattening/inversion and widened intercostal spaces
    - Tracheal deviation towards the contralateral side

,

CT: In stable adults without severe respiratory compromise and responsive to resuscitation. Other indications:
- Presurgical workup
- Suspected underlying lung disease, to determine the likelihood of recurrent disease
- Uncertain diagnosis despite chest x-ray

ECG: for all patients with anterior chest trauma
- Reduced QRS amplitude in leads V2–V6 in left-sided pneumothorax
- Increased QRS amplitude in leads V5–V6 in right-sided pneumothorax
- ST elevation or depression

A negative eFAST does not exclude a pneumothorax!

In cases of tension pneumothorax, immediate decompression is a priority and should not be delayed by imaging!References:^[1]^[4]

Differential diagnoses

For details and further differential diagnoses, see differential diagnoses of acute chest pain

The differential diagnoses listed here are not exhaustive.

Treatment

Approach

Simple pneumothorax
- If small (≤ 2 to 3 cm between the lung and chest wall on a chest x-ray) and asymptomatic
  - Usually resolve spontaneously within a few days (∼ 10 days)
  - Supplemental oxygen (4-6 L/min) via nasal cannula or mask with reservoir
  - Serial follow-up with repeat CXR
- If small and symptomatic (but hemodynamically stable) or large (> 3 cm between the lung and chest wall on chest x-ray) primary pneumothorax, iatrogenic, traumatic, or secondary pneumothorax
  - Immediate supplemental oxygen (4-6 L/min) via nasal cannula or mask with reservoir
  - Upright positioning
  - Symptomatic treatment
  - Tube thoracostomy
Open pneumothorax
- Simple partially occlusive dressings taped at 3 out of 4 sides of the lesion
- Followed by thoracostomy
- Observe for development of tension pneumothorax
Tension pneumothorax
- Emergency chest decompression via chest tube placement if immediately available
- Otherwise perform emergency needle thoracostomy, followed by chest tube placement

Procedures

Chest tube placement
- Approaches
  - Bülau drain: 4^th intercostal space (nipple line) in between anterior and median axillary line (safe triangle; midaxillary line)
Needle thoracostomy
- Immediate insertion of a large-bore needle into the 2^nd intercostal space along the midclavicular line (followed by insertion of a chest tube)

Surgery

Indications
- Repeated ipsilateral pneumothorax episodes
- Unexpanded lung > 5 days despite chest tube placement
- Air leak > 7 days
- Bilateral or contralateral pneumothorax
- Associated high risk occupation
- Extensive underlying lung disease
- Lymphangiomyomatosis
Procedures
- Video-assisted thoracoscopic surgery (VATS)
- Thoracotomy if necessary
Approaches
- Stitching of the leak or resection of the lung regions that have bullae, if necessary (apical lung resection)
- Pleurodesis
  - Chemical/pharmacological (administration into the pleural space): talc powder , bleomycin, tetracycline
  - Mechanical/surgical: pleural abrasion, partial (apical) parietal pleurectomy

Tension pneumothorax is a clinical diagnosis and medical emergency! Immediate emergency chest decompression is indicated! Do not intubate and ventilate without decompressing first!

Complications

Complete pulmonary collapse → respiratory failure
Tension pneumothorax → cardiac failure

Mediastinal flutter in case of open pneumothorax → hemodynamic shock

Hemothorax in cases of trauma
Pneumomediastinum
Pneumoperitoneum
Recurrence
Post-surgical/-procedural complications
- Persistent fistula with continuous air leak
- Injury to intercostal nerves and vessels
- Infection

References:^[1]

We list the most important complications. The selection is not exhaustive.