Last updated: November 17, 2023

Summarytoggle arrow icon

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.

Definitiontoggle arrow icon

  • 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

Epidemiologytoggle arrow icon

Epidemiological data refers to the US, unless otherwise specified.

Etiologytoggle arrow icon

Spontaneous pneumothorax

Traumatic pneumothorax

Any type of pneumothorax may lead to tension pneumothorax.

Pathophysiologytoggle arrow icon

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

Clinical featurestoggle arrow icon

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

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

Diagnosticstoggle arrow icon

General principles [8]

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]

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

Ultrasound [9]

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.

Differential diagnosestoggle arrow icon

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

Pneumomediastinum [17]

The differential diagnoses listed here are not exhaustive.

Treatmenttoggle arrow icon

Approach [6][8]

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

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]

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

Traumatic pneumothorax management [23][24]

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]

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.


Emergency chest decompression

Chest tube placement

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

Needle aspiration [23][27][28]


Dispositiontoggle arrow icon

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:

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.

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 checklisttoggle arrow icon

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

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

All patients

Unstable patients or patients with bilateral pneumothorax

Primary spontaneous pneumothorax (stable patient)

Secondary spontaneous pneumothorax (stable patient)

Acute management checklist for traumatic pneumothorax

Complicationstoggle arrow icon

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

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Referencestoggle arrow icon

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