Spontaneous pneumothorax

"Spontaneous" essentially refers to all pneumothoraces of "non-traumatic" etiologies


Secondary Causes

Clinical Features

Differential Diagnosis

Pneumothorax Types

The pleural cavity is normally a potential space, in which air collects in a pneumothorax.

Acute dyspnea





Clinically Stable

Defined as having all of the following:

  • Resp rate < 24
  • Heart rate 60-120 beats per minute
  • Normal BP
  • SaO2 >90% on room air and patient can speak in whole sentences


  • CXR
    • Displaced visceral pleural line without lung markings between pleural line and chest wall
    • Upright is best
      • Expiratory films DO NOT improve accuracy[1]
      • Lateral decubitus films with suspected side up do increase sensitivity. Good approach in pediatrics to avoid CT
    • Supine CXR = deep sulcus sign
  • CT Chest
    • Very sensitive and specific

Lung ultrasound of pneumothorax

  • No lung sliding seen (not specific for pneumothorax)
  • May also identify "lung point": distinct point where you no longer see lung sliding (pathognomonic)
  • Absence of lung sliding WITHOUT lung point could represent apnea or right mainstem intubation
  • Evaluate other intercostal spaces because pneumothorax may only be seen in least dependent area of thorax
    • NO comet tail artifact
    • Bar Code appearance/"Stratosphere" sign on M-mode (absence of "seashore" waves)
  • Ultrasound has greater sensitivity than chest x-ray for pneumothorax in trauma patients [2]

Estimating Pneumothorax Size

Measuring pneumothoraxes. Line A = lung apex to cupola. Line B = interpleural distance.
  • On a conventional, upright posterior-anterior chest radiograph:
    • Very small: <1 cm interpleural distance (confined to upper 1/3 of chest) OR only seen on CT
    • Small: ≤3cm lung apex to cupola (chest wall apex) on CXR
    • Large: >3cm lung apex to cupola (chest wall apex) on CXR
3cm apex to cupola measurement is roughly equivalent to 2cm interpleural distance (at the level of the hilum)
Both roughly correlate with a 50% pneumothorax by volume


Rearanged British Thoracic Society (BTS) guidelines for spontaneous pneumothorax

Supplemental oxygen (non-rebreather mask) initially for all


  • Needle decompression followed by chest tube insertion
  • ATLS guidelines recommend 5cm angiocath at 2nd intercostal space at the mid-clavicular line
  • More recent evidence shows higher success rates with 4th/5th intercostal space at the anterior or mid-axillary line

Primary Spontaneous Pneumothorax (Stable)

First Episode

  • Small AND asymptomatic (no dyspnea)
  • Large OR symptomatic (e.g. dyspnea)
    • Aspiration (see below)
      • If fail, admit with chest tube to suction for thoracoscopy (VATS)^
BTS Pneumothorax.png
  • British Thoracic Society Protocol[4]
  • 2020 study supports conservative therapy vs chest tube. [5] however there are issues with study including “significant drop out rate, the relatively large number of protocol violations, the large inferiority margins and the short intervention time.”[6]
    • Inclusion criteria
      • 14 to 50 years of age
      • unilateral primary spontaneous pneumothorax of 32% or more on chest radiography according to the Collins method (sum of interpleural distances, >6 cm)
    • Exclusion criteria [7]
      • Secondary pneumothorax, defined as pneumothorax occurring in the setting of acute trauma (including iatrogenic) or underlying lung disease including but not limited to COPD, pulmonary fibrosis, TB, cystic fibrosis, lung cancer and asthma that requires regular preventative medication or has been symptomatic within the last two years
      • Previous spontaneous pneumothorax on the same side 3. Coexistent haemothorax (i.e. spontaneous haemopneumothorax)
      • Bilateral pneumothorax
      • Clinical instability suggesting tension pneumothorax; respiratory distress persisting despite oxygen and parenteral narcotic analgesia (RR >30/min or SpO2 <90%), SBP <90 mmHg, HR greater than or equal to SBP.
      • Pregnancy at time of enrolment
      • Social circumstances whereby the patient either does not have adequate support after discharge to re-attend hospital if required, or is unlikely to present for study follow up.
      • Air travel within the next 12 weeks if this cannot be deferred should the pneumothorax be slow to resolve"
    • Observed for a minimum of 4 hours then repeat chest X-ray.
    • Discharge if no supplementary oxygen and walking comfortably,
    • Chest tubes placed if:
      • clinically significant symptoms persisted despite adequate analgesia
      • chest pain or dyspnea prevented mobilization
      • patient was unwilling to continue with conservative treatment
      • the patient’s condition became physiologically unstable (systolic blood pressure of <90 mm Hg, heart rate in beats per minute greater than or equal to systolic blood pressure in millimeters of mercury, respiratory rate of >30 breaths per minute, or Spo2 of <90% while the patient was breathing ambient air)
      • repeat chest radiograph showed an enlarging pneumothorax along with physiological instability.

Recurrent OR Hemopneumothorax

^If thoracoscopy (VATS) is not readily available, chemical pleurodesis through the chest tube

Secondary Pneumothorax (Stable)

  • Asymptomatic AND very small (<1 cm interpleural distance)
  • Asymptomatic AND small
    • Chest tube (some centers may choose needle aspiration under ultrasound guidance)
    • Observation alone associated with some mortality
  • Symptomatic OR large OR bilateral
Admit all secondary pneumothoraxes

Needle Aspiration of Pneumothorax

  • Use thoracentesis or "pig-tail" kit, if available
  • Place in 2nd IC space in midclavicular line or 4th/5th IC space in anterior axillary line
  • Withdraw air with syringe until no more can be aspirated
    • Assume a persistent air leak (failure) if no resistance after 4 liters of air has been aspirated AND the lung has not expanded
  • Once no further air can be aspirated:
    • Option 1
      • Place closed stopcock and secure catheter to the chest wall
      • Obtain CXR four hours later
      • If adequate lung expansion has occurred, remove catheter
      • Following another two hours of observation, obtain another CXR
      • If the lung remains expanded, may discharge patient
    • Option 2
      • Leave catheter in place
      • Attached a Heimlich (one-way) valve
      • May discharge with follow-up within two days
  • If 2.5 L of air has been aspirated, and a significant PTX remains, tube thoracostomy is indicated
  • NEJM video on needle aspiration of pneumothorax.

Adult Chest Tube Sizes

Chest Tube Size Type of Patient Underlying Causes
Small (8-14 Fr)
  • Alveolar-pleural fistulae (small air leak)
  • Iatrogenic air
Medium (20-28 Fr)
  • Trauma/bleeding (hemothorax/hemopneumothorax)
  • Bronchial-pleural fistulae (large air leak)
  • Malignant fluid
Large (36-40 Fr)
  • Thick pus



  • See Management section


  • All admitted (even if small and clinically stable)

Special Instructions


  • Can consider flying 2 weeks after full resolution of traumatic pneumothroax[3]


See Also


  1. Eur Respir J. 1996 Mar;9(3):406-9
  2. Nagarsheth K, Kurek S. Ultrasound detection of pneumothorax compared with chest X-ray and computed tomography scan. Am Surg. 2011 Apr;77(4):480-4. PMID: 21679560.
  3. 3.0 3.1 "Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010" British Thoracic Society Guidelines. Thorax 2010;65:ii18-ii31 doi:10.1136/thx.2010.136986 PDF
  4. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010 https://thorax.bmj.com/content/65/Suppl_2/ii18
  5. EBQ:Conservative versus interventional treatment for spontaneous pneumothorax
  6. https://www.stemlynsblog.org/jc-conservative-management-of-pneumothoraces/
  7. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12611000184976
  8. Inaba Et. al J Trauma Acute Care Surg. 2012 Feb;72(2):422-7.
  9. Advanced Trauma Life Support® Update 2019: Management and Applications for Adults and Special Populations.