Pneumothorax

Pneumothorax develops when air enters the pleural space as the result of disease or injury. This leads to a loss of negative pressure between the two pleural membranes, which can result in the partial or complete collapse of the lung. Pneumothorax is classified as spontaneous or traumatic. Spontaneous pneumothorax can be further classified as primary (i.e., no underlying lung disease) or secondary (i.e., due to underlying lung disease). Any type of pneumothorax can progress to tension pneumothorax, which is a life-threatening variant of pneumothorax. Patients with pneumothorax usually present with sudden-onset dyspnea, ipsilateral chest pain, diminished breath sounds, and hyper-resonant percussion on the affected side. Tension pneumothorax further manifests with distended neck veins, tracheal deviation, and hemodynamic instability. There should be a high index of suspicion for both conditions on clinical evaluation. Unstable patients with tension pneumothorax require immediate needle decompression. Chest x-ray may be used to confirm the diagnosis in stable patients. Small pneumothoraces may resorb spontaneously, but larger defects usually require placement of a chest tube.

• 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.

• A collection of air within the pleural space between the lung (visceral pleura) and the chest wall (parietal pleura) that can lead to partial or complete pulmonary collapse ^[2]
• May be classified as:
  • Spontaneous pneumothorax
    • Primary spontaneous pneumothorax: occurs in patients without clinically apparent underlying lung disease
    • Secondary spontaneous pneumothorax: occurs as a complication of underlying lung disease
    • Recurrent pneumothorax: a second episode of spontaneous pneumothorax, either ipsilateral or contralateral
  • Traumatic pneumothorax: a type of pneumothorax caused by a trauma (e.g., penetrating injury, iatrogenic trauma)
  • Tension pneumothorax:: a life-threatening variant of pneumothorax characterized by progressively increasing pressure within the chest and cardiorespiratory compromise

Spontaneous pneumothorax

• Primary (idiopathic or simple pneumothorax)
  • Caused by ruptured subpleural apical blebs
  • Risk factors
    • Family history
    • Male gender
    • Young age
    • 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 the cumulative number of cigarettes smoked)
    • Homocystinuria
• Secondary (pneumothorax as a complication of underlying lung disease)
  • COPD (smoking) → rupture of bullae in emphysema
  • Pulmonary tuberculosis
  • Cystic fibrosis → bronchiectasis with obstructive emphysema and bleb or cyst rupture
  • Pneumocystis pneumonia → alveolitis, rupture of a cavity
  • Catamenial pneumothorax (thoracic endometriosis): extremely rare

Traumatic pneumothorax

• Blunt trauma (e.g., motor vehicle accident in which the thorax hits the steering wheel or rib fracture occurs)
• Penetrating injury (e.g., gunshot, stab wound)
• Iatrogenic pneumothorax: mechanical ventilation with high PEEP (barotrauma); , thoracocentesis; , central venous catheter placement; , bronchoscopy, lung biopsy

Any type of pneumothorax may lead to tension pneumothorax.References:^[1]

• 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
• 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:^[3]

Patients range from being asymptomatic to having features of hemodynamic compromise. ^[4]

• 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
• Addition findings in tension pneumothorax ^[5]
  • 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 may be present (e.g., open or closed wounds).
  • Signs of tension pneumothorax in ventilated patients ^[5]
    • Tachycardia, hypotension
    • Rapid decrease in SpO₂
    • Reduced air flow
    • Increased ventilation pressure
    • Skin emphysema

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

General principles ^[6]

• The diagnosis of pneumothorax is usually confirmed by chest x-ray.
  • Ultrasound is becoming an increasingly accepted modality for identifying pneumothorax and is part of the eFAST. ^[7][4]
  • CT can provide 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 in favor of initiating immediate treatment.

In cases of tension pneumothorax, immediate decompression is a priority and should not be delayed by imaging.

Imaging

Chest x-ray ^[4][6]

• Indications: all patients suspected of having pneumothorax
• Procedure: Upright PA chest x-ray in inspiration is the modality of choice. ^[4][8]
• Supportive findings of pneumothorax
  • Ipsilateral pleural line with reduced/absent lung markings (i.e., increased transparency)
  • Abrupt change in radiolucency
  • Deep sulcus sign
    • Decreased radiodensity and deep costophrenic angle on the ipsilateral side ^[9]
    • The sign is a result of interpleural air that collects basally and anteriorly in the supine position.
  • Hemidiaphragm elevation on the ipsilateral side
  • If pulmonary disease is present: airway or parenchymal lesions
• Supportive findings of tension pneumothorax
  • Ipsilateral diaphragmatic flattening/inversion and widened intercostal spaces
  • Mediastinal shift toward the contralateral side
  • Tracheal deviation toward the contralateral side ^[10][11]

Ultrasound ^[7]

• Indications
  • Trauma (eFAST)
  • Quick bedside assessment
• Supportive findings ^[12]
  • Absence of pleural sliding
  • Absence of B-lines
  • Barcode sign instead of seashore sign in M-mode
  • Combination of prominent A-lines and absent B-lines

Chest CT ^[4]

• Indications
  • Uncertain diagnosis despite chest x-ray and complex cases
  • In suspected underlying lung disease, to determine the likelihood of recurrent disease
  • Detailed assessment of bullae
  • Presurgical workup
• Findings: similar to CXR

Determination of pneumothorax size

The size of a pneumothorax is assessed via imaging (e.g., CXR, CT chest). How a pneumothorax is measured depends on regional guidelines, hospital policies, and personal preferences:

• Apex-to-cupola distance ^[6]
• Interpleural distance at the level of the lung hilus ^[4]
• Collins method: Calculated pneumothorax size in percent of hemithorax ^[13][14]
  • The interpleural distance on a PA CXR is measured in centimeters at three points.
  • Apex-to-cupola distance (A)
  • Midpoints of upper (B) and lower (C) half of collapsed lung
  • Pneumothorax size as a percent of the ipsilateral hemithorax = 4.2 + 4.7 x (A + B + C)

Laboratory studies

Laboratory analysis is generally not indicated.

• Arterial blood gas analysis (ABG) ^[4]
  • Indications
    • SpO₂ < 92% on room air
    • Evaluation for CO₂ retention in patients with lung disease (e.g., COPD) receiving supplemental O₂
  • Findings: ↓PaO₂ may be present

Approach ^[4][6]

• Assess patient stability (see stability criteria for spontaneous pneumothorax)
• Provide respiratory support and treat dyspnea
• Evaluate the type and size of pneumothorax
  • Tension pneumothorax, unstable patients, bilateral pneumothorax: immediate chest decompression
  • Spontaneous pneumothorax: conservative management or chest tube placement
  • Mechanical ventilation necessary: chest tube placement

In every patient with pneumothorax who requires mechanical ventilation, immediate tube thoracostomy should be performed first.

Positive pressure ventilation can turn a simple pneumothorax into a life-threatening tension pneumothorax.

Stability criteria for spontaneous pneumothorax ^[6]

All of the following must be present for the patient to be considered stable:

• Respiratory rate < 24 breaths/minute
• SpO₂ (room air): > 90%
• Patient able to speak in complete sentences
• HR 60–120/minute
• Normal BP

All other patients are considered unstable.

Respiratory support

• Upright positioning
• Provide supplemental high-flow oxygen as needed (target SpO₂ ≥ 96%) ^[4]
• If a patient requires mechanical ventilation, emergency chest tube placement is indicated.
  • Positive pressure ventilation can turn a simple pneumothorax into a life-threatening tension pneumothorax.
  • Decompression of a pneumothorax can sometimes rapidly improve dyspnea, making mechanical ventilation unnecessary.
• See also airway management and oxygen therapy.

Management based on pneumothorax type and size

Tension pneumothorax, unstable patients, and bilateral pneumothorax ^[4][5][6]

• Suspected tension pneumothorax: emergency needle thoracostomy, followed by chest tube placement ^[5]
• Unstable patients or bilateral pneumothorax: emergency chest decompression via chest tube placement

Tension pneumothorax is a clinical diagnosis and a medical emergency requiring immediate chest decompression.

Primary spontaneous pneumothorax (stable patient) ^[4][6]

• Apex-to-cupula distance < 3 cm
  • Usually resolves spontaneously within a few days (∼ 10 days) ^[15]
  • Serial follow-up with repeat chest x-ray
    • Repeat CXR after observation for 3–6 hours to exclude progression prior to discharge.
    • Consider outpatient management with follow-up within 2 days. ^[6][4]
• Apex-to-cupula distance ≥ 3 cm
  • Chest tube placement typically recommended
  • Consider conservative management in otherwise healthy patients without respiratory distress and no progress in repeat CXR after 4 hours. ^[14][16][17]
  • Needle aspiration may also be considered. ^[4]

Secondary spontaneous pneumothorax, age > 50 years, or history of smoking (stable patient) ^[4][6]

• Apex-to-cupula distance < 3 cm: Consider observation or chest tube placement.
• Apex-to-cupula distance ≥ 3 cm
  • Chest tube placement
  • ICU transfer and thoracic surgery consultation

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.

Procedures

• Needle thoracostomy
  • Indication: tension pneumothorax
  • Procedure:
    • Immediate insertion of a large-bore needle into the second intercostal space along the midclavicular line
    • Typically followed by the insertion of a chest tube
    • If initial decompression fails, consider using a longer needle (especially in muscular/adipose patients) ^[4][18]
• Chest tube placement ^[19]
  • Indications: see above
  • Procedure
    • Most commonly in the 4^th–5^th intercostal space (nipple line), between the anterior and median axillary line (safe triangle )
    • Rarely: second intercostal space, midclavicular line (Monaldi drain)
      • The intercostal space is very narrow at this site and the pectoralis muscle must be penetrated. ^[19]
      • Primarily used for emergency chest decompression
    • Connect tubing to water seal or suctioning ^[4]
    • Always check CXR after the procedure is complete.
• Surgery
  • Indications ^[4]
    • Recurrent ipsilateral pneumothorax episodes
    • Bilateral or contralateral pneumothorax
    • Persistent air leak or insufficient lung re-expansion for 5–7 days despite chest tube placement
    • Extensive underlying lung disease
    • High-risk occupation (e.g., pilots)
  • 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.
    • Pleurodesis
      • Mechanical/surgical: pleural abrasion, pleurectomy (complete or incomplete) ^[4]
      • Chemical/pharmacological (administration into the pleural space): talc powder , doxycycline, minocycline ^[4][6]

Always check a CXR after chest tube placement or needle thoracostomy.

• 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.