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.

• Pneumothorax: 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. May be classified as: ^[1]
• 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

• Primary spontaneous pneumothorax ^[2]
  • Sex: ♂ > ♀ (∼ 6:1)
  • Peak incidence: 16–25 years
• Secondary spontaneous pneumothorax
  • Sex: ♂ > ♀ (∼ 3:1) ^[3]
  • Peak incidence: 60–65 years ^[4]

Epidemiological data refers to the US, unless otherwise specified.

Spontaneous pneumothorax

• Primary (idiopathic or simple pneumothorax)
  • Caused by ruptured subpleural apical blebs
  • Risk factors
    • Family history
    • Male sex
    • Young age
    • Asthenic body habitus (slim, tall stature)
    • 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
  • Infections
    • Pulmonary tuberculosis
    • Pneumocystis pneumonia → alveolitis, rupture of a cavity
  • Cystic fibrosis → bronchiectasis with obstructive emphysema and bleb or cyst rupture
  • Marfan syndrome
  • Malignancy
  • 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.

Increased intrapleural pressure → alveolar collapse → decreased V/Q ratio and increased right-to-left shunting. ^[5]

• 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
  1. Disrupted visceral pleura, parietal pleura, or tracheobronchial tree
  2. One-way valve mechanism, in which air enters the pleural space on inspiration but cannot exit
  3. Progressive accumulation of air in the pleural space and increasing positive pressure within the chest
  4. Collapse of ipsilateral lung; compression of contralateral lung, trachea, heart, and superior vena cava; angulation of inferior vena cava
  5. Impaired respiratory function, reduced venous return to the heart
  6. Reduced cardiac output
  7. Hypoxia and hemodynamic instability

Patients range from being asymptomatic to having features of hemodynamic compromise. ^[6]

• 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
• Additional findings in tension pneumothorax ^[7]
  • 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 ^[7]
    • Tachycardia, hypotension (obstructive shock)
    • Distention of jugular vein
    • 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-ray show collapse.

General principles ^[8]

• 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. ^[6][9]
  • 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 of pneumothorax

Chest x-ray ^[6][8]

• Indications: all patients suspected of having pneumothorax
• Procedure: Upright PA chest x-ray in inspiration is the modality of choice. ^[6][10]
• 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 ^[11]
    • 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 ^[12][13]

Pneumothorax is very difficult to identify on supine CXR; consider ultrasound or CT chest in patients unable to sit upright.

Ultrasound ^[9]

• Indications
  • Trauma (eFAST)
  • Quick bedside assessment
• Supportive findings ^[14]
  • 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 ^[6]

• 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 ^[8]
• Interpleural distance at the level of the lung hilus ^[6]
• Collins method: Calculated pneumothorax size in percent of hemithorax ^[15][16]
  • 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) ^[6]
  • 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

See also “Differential diagnoses of chest pain“ and “Differential diagnoses of dyspnea.”

Pneumomediastinum ^[17]

• Definition: presence of gas (usually air) in the mediastinum
• Etiology
  • Primary (spontaneous)
    • Rupture of pulmonary blebs
    • Predisposing factor: smoking
  • Secondary
    • Traumatic: blunt or penetrating injuries of chest and/or abdomen
    • Nontraumatic
      • Boerhaave syndrome
      • Bronchiectasis
      • COPD
      • Asthma
      • Interstitial lung disease
      • Lung cancer
    • Iatrogenic
      • Endoscopy
      • Intubation
      • Central line placement
• Pathophysiology: ↑ intra-alveolar pressure → rupture of alveoli → air travel along the peribronchial and perivascular sheaths to enter the mediastinum
• Clinical features
  • Chest pain
    • Sudden in onset
    • Retrosternal
    • Radiates to the neck or back
  • Dyspnea
  • Subcutaneous emphysema
  • Cough
  • Voice change
    • Rhinolalia
      • Nasal quality of voice
      • Occurs due to the presence of air within the soft palate
    • Hoarseness
  • Hamman sign: precordial crepitation that is audible synchronous to the heartbeat
• Diagnostics
  • CXR
    • Air outlining the mediastinal structures (e.g. aorta, trachea)
    • Visible mediastinal pleura
  • CT scan: performed if CXR findings are inconclusive
• Management: usually self-limited when associated with barotrauma
  • Clinical and radiographic monitoring
  • Ventilation pressure reduction
  • For traumatic causes, see also “Approach to blunt chest trauma” and “Approach to penetrating chest trauma.”

The differential diagnoses listed here are not exhaustive.

Approach ^[6][8]

• All patients
  • Assess patient stability (see, e.g., “Stability criteria for spontaneous pneumothorax”).
  • Provide respiratory support and treat dyspnea.
  • Evaluate the type and size of pneumothorax.
• Unstable or high-risk patients: e.g., with tension pneumothorax, bilateral pneumothorax, or who require mechanical ventilation
  • Immediate chest decompression
  • Treat obstructive shock if present.
• Stable spontaneous pneumothorax management: depends on the risk of progression and recurrence
  • Low-risk: conservative management
  • Higher risk: chest tube placement
• Traumatic pneumothorax management
  • Most patients require chest tube placement.
  • Follow the ABCDE approach to trauma to assess for additional injuries.
• Monitoring and disposition
  • Consider the following consults :
    • Pulmonology: stable spontaneous pneumothoraces
    • Thoracic surgery: traumatic pneumothoraces, large secondary pneumothoraces
    • ICU: unstable patients or those with large secondary pneumothoraces
  • Regularly reassess patients for:
    • Clinical features of deterioration
    • Development or recurrence of a tension pneumothorax
  • See also “Disposition of patients with pneumothorax.”

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.

Respiratory support

• Upright positioning
• Provide supplemental high-flow oxygen as needed (target SpO₂ ≥ 96–100%) ^[6]
• 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”.

Start all patients without risk factors for hypercapnia on high-flow oxygen as soon as pneumothorax is suspected because high-flow oxygen aids reabsorption of the pneumothorax, which accelerates recovery.

Spontaneous pneumothorax management

Stability criteria for spontaneous pneumothorax ^[8]

• 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.

Treatment based on stability, type, and size

For stable patients, management depends on apex-to-cupola distance. ^[6][8]

• Unstable (high risk) ^[6][7][8]
  • Suspected tension pneumothorax
    • Emergency needle thoracostomy, followed immediately by chest tube placement ^[7]
    • Consider a finger thoracostomy if needle thoracostomy is unsuccessful. ^[7][18]
  • Bilateral pneumothorax OR any patients who either require mechanical ventilation or do not meet pneumothorax stability criteria: Emergency chest tube placement
• Stable (low risk): Primary spontaneous pneumothorax ^[6][8]
  • Apex-to-cupola distance < 3 cm
    • Usually resolves spontaneously within a few days (∼ 10 days) ^[19]
    • Perform a repeat chest x-ray at 3–6 hours:
      • Stable or improving appearance: Consider outpatient management (see “Disposition of patients with pneumothorax”). ^[6][8]
      • Enlarging appearance: Place a chest tube.
  • Apex-to-cupola distance ≥ 3 cm
    • Chest tube placement typically recommended
    • Consider conservative management in otherwise healthy patients able to adhere to management instructions and experiencing : ^[16][20][21]
      • An initial episode
      • No respiratory distress or progression on repeat 4-hour CXR
    • Needle aspiration may also be considered. ^[6][22]
• Stable (higher risk): Secondary spontaneous pneumothorax OR primary spontaneous pneumothorax with risk factors (i.e., age > 50 years, history of smoking, or recurrent disease) ^[6][8][23]
  • Apex-to-cupola distance < 3 cm: Consider observation or chest tube placement. ^[8]
  • Apex-to-cupola distance ≥ 3 cm
    • Chest tube placement
    • ICU transfer and thoracic surgery consultation

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

Traumatic pneumothorax management ^[23][24]

• The treatment of unstable or high-risk traumatic pneumothorax (e.g., tension pneumothorax) is identical to the treatment of unstable spontaneous pneumothorax: emergency chest decompression.
• Consider observation only in hemodynamically stable patients with small pneumothoraces. ^[25]
• A chest tube is required for all patients with any of the following:
  • Suspected or proven hemopneumothorax
  • Ongoing or anticipated mechanical ventilation
  • Moderate to large pneumothorax
  • Small pneumothorax with hemodynamic instability
• Suspected hemopneumothorax: Use a large-bore chest tube.
• Significant chest trauma: Assess for other thoracic injuries, e.g., rib fractures, pulmonary contusions (see “Management of trauma patients”).

As patients with a traumatic pneumothorax may have other injuries affecting multiple areas of the body, a full primary survey should be performed and ATLS management principles followed.

Open pneumothorax ^[23][24]

• Immediately apply simple, partially occlusive dressings taped at 3 out of 4 sides of the lesion.
• Follow dressing with tube thoracostomy.
• Observe for development of tension pneumothorax.

Never pack the chest wound in an open pneumothorax as the packing may be sucked into the chest cavity during inspiration!

Do not tape the dressing on all 4 sides of the lesion because this can lead to a tension pneumothorax resulting from air building up in the thoracic cavity instead of being released during exhalation.

Procedures

Emergency chest decompression

• Needle thoracostomy
  • Indication: tension pneumothorax
  • Procedure:
    • Immediate insertion of a large-bore needle
      • In adults: use the 2^nd intercostal space at the midclavicular line or the 4^th–5^th intercostal space between the anterior and midaxillary line (especially in muscular or obese patients) ^[24]
      • In children: use the 2^nd intercostal space at 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) ^[6][26]
• Finger thoracostomy
  • Indications
    • Tension pneumothorax with unsuccessful needle decompression
    • Traumatic cardiac arrest
  • Procedure
    • Initial steps: identical to chest tube placement
    • Difference compared to chest tube placement
      • A gloved finger is inserted into the pleural space to create an open pneumothorax.
      • No chest tube is inserted or secured.

Chest tube placement

• Indications: see “Approach” and “Spontaneous pneumothorax management.”
• Procedure
  • Most commonly in the 4^th–5^th intercostal space (nipple line), between the anterior and midaxillary line (safe triangle )
  • The chest drainage system may be used with or without suction. ^[6]
  • Always check CXR after the procedure is complete.
  • See “Chest tube placement” for detailed procedural guidance.

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

Needle aspiration ^[23][27][28]

• Indication: stable patients with a large (apex-to-cupola distance ≥ 3 cm) spontaneous primary pneumothorax
• Procedure
  • Insert a 16–18 g IV cannula through either of the following landmarks:
    • 2^nd or 3^rd ICS, midclavicular line
    • 4^th ICS anterior axillary line
  • Attach a three-way stopcock to the needle.
  • Aspirate air using a large syringe until resistance is felt or the patient begins to cough excessively.

Surgery

• Indications ^[6]
  • 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) ^[6]
    • Chemical/pharmacological (administration into the pleural space): talc powder , doxycycline, minocycline ^[6][8]

Follow local hospital protocols and base disposition decisions on individual patient needs, in consultation with a specialist, e.g., trauma surgeon, pulmonologist, or thoracic surgeon.

Admission criteria ^[23]

Patients requiring a chest tube typically require hospital admission, except for those meeting select criteria for home management. However, these criteria do not apply to the following conditions, in which admission is always recommended:

• All patients with :
  • Tension pneumothorax
  • Secondary spontaneous pneumothorax
  • Traumatic pneumothorax
• Patients with spontaneous primary pneumothorax and any of the following:
  • Signs of hypoxia or hemodynamic instability
  • Evidence of progression on repeat chest x-ray
  • Difficulty adhering to discharge instructions

Consider ICU admission for unstable patients or those with large secondary pneumothoraces.

Trauma center ^[24]

Transfer to a trauma center is recommended for patients with traumatic pneumothorax and any of the following once stabilizing procedures have been performed.

• Tension pneumothorax: after needle thoracostomy/finger thoracostomy and chest tube placement
• Open pneumothorax or hemopneumothorax: after portable CXR and chest tube placement
• Respiratory failure: after intubation and chest tube placement
• Other injuries that meet requirements for trauma center transfer, for example:
  • Associated thoracic injuries: e.g., flail chest, pulmonary contusions
  • Other multisystem injuries: e.g., traumatic brain injury, penetrating abdominal trauma

Perform emergency interventions to stabilize patients (e.g., chest tube placement, intubation) prior to interfacility transfer whenever possible.

Criteria for outpatient management ^[8][23]

• Patients must be able to:
  • Understand discharge instructions
  • Attend 24–48 hour follow-up ^[6][8]
• Imaging criteria for stable patients with spontaneous primary pneumothorax
  • Managed with observation only: improved or stable on repeat CXR at 3–6 hours
  • Managed with needle aspiration: improved on repeat CXR 4–6 hours after aspiration

Discharge instructions ^[6][23]

• Advise patients to seek immediate medical attention if breathlessness or chest pain worsens.
• Arrange follow-up with the patient's primary care physician for 24–48 hours following discharge.
• Advise patients not to fly until they have had one week of full resolution of the pneumothorax.
• Inform patients that they should abstain from scuba diving for life.
• Educate patients on the risk of recurrence (1 in 3 patients).
  • Provide support for smoking cessation (continued smoking is associated with an increased risk of recurrence).
  • In patients for whom a recurrence would place them at high risk (regular fliers, scuba divers), consider referral to a cardiothoracic surgeon.

Acute management checklist for tension pneumothorax ^[7][29]

• Administer high-concentration supplemental oxygen (100% F_iO₂).
• Avoid positive pressure ventilation.
• Perform emergency needle decompression if the patient is hemodynamically unstable, followed by tube thoracostomy.
• Serial CXR
• Continuous telemetry, continuous pulse oximetry
• Transfer to ICU.

Acute management checklist for spontaneous pneumothorax ^[6][8][29]

All patients

• Continuous telemetry, continuous pulse oximetry
• Start supplemental oxygen in all patients with no risk factors for hypercapnia: target SpO₂ ≥ 96% (in the absence of chronic CO₂ retention).
• Avoid positive-pressure ventilation.
• Any patient who requires mechanical ventilation should first undergo tube thoracostomy.

Unstable patients or patients with bilateral pneumothorax

• Chest tube insertion with water seal with or without suction
• Order repeat CXR after chest tube insertion.
• ICU transfer
• Consult thoracic surgery.

Primary spontaneous pneumothorax (stable patient)

• Small pneumothorax (< 3 cm apex-to-cupola distance)
  • Monitor closely.
  • Order repeat CXR in 3–6 hours.
    • If stable or improved, consider discharge.
    • If worsening, start treatment for a large pneumothorax.
• Large pneumothorax (≥ 3 cm apex-to-cupola distance)
  • Either needle aspiration or chest tube/catheter insertion to water seal or Heimlich valve until lung re-expands
  • Order repeat CXR after chest tube insertion.

Secondary spontaneous pneumothorax (stable patient)

• Small pneumothorax (< 3 cm apex-to-cupola distance)
  • Admission with monitoring for 24 hours
  • Consider chest tube insertion to water seal or Heimlich valve until lung re-expands.
  • Order repeat CXR after chest tube insertion.
  • Consult thoracic surgery.
• Large pneumothorax (≥ 3 cm apex-to-cupola distance)
  • Chest tube insertion to water seal or Heimlich valve until lung re-expands
  • Order repeat CXR after chest tube insertion.
  • Consider ICU transfer.
  • Consult thoracic surgery.

Acute management checklist for traumatic pneumothorax

• All patients
  • Assess for signs of instability; if present, perform immediate needle or finger thoracostomy followed by chest tube insertion.
  • Review the mechanism of injury; consider the risk of extrathoracic injuries.
  • Ensure adequate analgesia, particularly in patients with associated rib fractures.
  • Transfer to trauma center for: tension pneumothorax, hemopneumothorax, open pneumothorax, respiratory failure, or associated injuries requiring trauma center level of care.
  • Stabilize patients as needed prior to interfacility transfer: e.g., intubation, chest tube placement.
• Small pneumothorax
  • Determine if the patient has any risk factors necessitating a chest tube: e.g., suspected hemothorax, ongoing or anticipated mechanical ventilation.
  • If no risk factors are present, continue high-flow oxygen and observation.
• Moderate to large pneumothorax
  • Insert a chest tube and connect to a water seal until the lung re-expands.
  • Order repeat CXR after chest tube insertion.
  • Consider ICU transfer.

• Complete pulmonary collapse → respiratory failure
• Tension pneumothorax → cardiac failure
• Mediastinal flutter in 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

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

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