Pneumothorax and Pneumomediastinum

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Pneumothorax & Pneumomediastinum

Last reviewed: March 2026

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Pneumomediastinum

Patient presents with chest pain, dyspnea, and neck fullness. Examination reveals subcutaneous emphysema in the neck and chest wall, with a palpable air crackle on palpation. Chest imaging confirms pneumomediastinum without evidence of tension physiology or hemodynamic compromise. Vital signs are reassuring and the patient is well-appearing with normal oxygenation.

The most common etiology of pneumomediastinum is alveolar rupture from Valsalva during coughing, retching, or strenuous activity — spontaneous rupture of distal alveoli causes air dissection along the bronchovascular sheaths into the mediastinum. Key is ruling out dangerous secondary causes: esophageal or tracheobronchial injury (which would require urgent surgical evaluation), tension pneumomediastinum (which would cause hemodynamic collapse), and mediastinitis (which would accompany fever, elevated inflammatory markers, and progressive clinical deterioration). History and imaging findings reassure against these complications. No signs of hemodynamic compromise, airway obstruction, or sepsis.

Plan: Serial chest imaging obtained to assess for progression. Patient observed for hemodynamic stability and oxygenation. Nothing by mouth pending reassessment. Close monitoring for any change in vital signs, development of neck swelling, dyspnea progression, or hemodynamic instability.

Disposition: Admit for observation and serial imaging. Most pneumomediastinum from benign alveolar rupture resolves within 7-10 days with conservative management. Thoracic surgery consulted if any concern for tracheobronchial or esophageal injury, signs of tension physiology, or clinical deterioration. Inform patient of return precautions: worsening dyspnea, chest pain, syncope, hemodynamic instability, or fever should prompt immediate reevaluation.

Primary Spontaneous Pneumothorax — Small, Observation/Discharge

Patient presents with acute chest pain and dyspnea. Examination reveals diminished breath sounds on the affected side but the patient is hemodynamically stable, well-appearing, and maintaining adequate oxygenation. Imaging confirms a small primary pneumothorax (less than 2 cm at the hilum, or occupying less than 20% of hemithoracic volume). No significant mediastinal shift. Patient is a reliable follow-up candidate with close proximity to home and access to reevaluation if symptoms change.

History and exam reassure against secondary pneumothorax (no underlying lung disease, no recent trauma, no mechanical ventilation). This is a young, otherwise healthy patient with primary spontaneous pneumothorax from spontaneous visceral pleural rupture. Small size and hemodynamic stability support safe observation without immediate chest tube placement. The natural history is resorption: air in the pleural space is absorbed at a rate of approximately 1.25% per day, so small pneumothorax typically resolves completely within 1-2 weeks.

Plan: Observation initiated without chest tube. Patient provided with supplemental oxygen (high-flow oxygen accelerates air resorption by creating a pressure gradient favoring nitrogen resorption). Repeat chest imaging obtained at 48-72 hours to assess for progression or resolution. Patient monitored for any increase in dyspnea, chest pain, or hemodynamic instability. Pain control as needed.

If pneumothorax enlarges on follow-up imaging or patient becomes dyspneic: Chest tube placed emergently and patient admitted for inpatient management.

Disposition: Discharge home with reliable follow-up if pneumothorax remains stable and patient is reliable. Require repeat imaging at 48-72 hours and at 1-2 weeks to document resolution. Provide clear return precautions: return immediately if dyspnea worsens, chest pain increases, syncope occurs, or shortness of breath develops at rest. Advise against air travel and strenuous activity until complete resolution. Follow up with pulmonology or primary care for a repeat chest X-ray in 2-4 weeks to confirm complete resolution before resuming normal activities.

Primary Spontaneous Pneumothorax with Chest Tube

Patient presents with chest pain and dyspnea. Examination reveals significantly diminished breath sounds on the affected side. Imaging confirms a primary spontaneous pneumothorax of substantial size (greater than 2 cm at the hilum, or occupying more than 20% of hemithoracic volume) or a smaller pneumothorax in a patient with significant dyspnea, inability to tolerate observation, or unreliable follow-up. Patient may have failed prior observation trial with progression of pneumothorax.

A chest tube is indicated. The pneumothorax is large enough or the patient’s symptoms/reliability warrant intervention beyond observation. Primary pneumothorax indicates no underlying structural lung disease — this is first-line treatment and frequently results in lung re-expansion and successful resolution.

Plan: Chest tube placed (pigtail catheter 14 French preferred for most pneumothorax — small, flexible, well-tolerated, effective at resolving uncomplicated PTX). Tube connected to a one-way valve or low-suction system (20 cm H2O). Patient admitted for inpatient observation and serial imaging to assess lung re-expansion. Oxygen provided to accelerate air resorption. Monitor for any air leak, subcutaneous emphysema, or hemodynamic change.

Disposition: Admit to floor bed (or ICU if hemodynamic instability, significant respiratory compromise, or bilateral pneumothorax). Once lung is fully re-expanded on imaging and there is no persistent air leak, chest tube can be removed. Most uncomplicated primary pneumothorax resolves within 3-5 days of chest tube placement and observation. Arrange pulmonology follow-up and provide strong counseling regarding recurrence (primary PTX has 20-50% recurrence rate) and smoking cessation. Advise patient to avoid air travel for at least 2 weeks after complete resolution and to avoid strenuous activity for 2-4 weeks. Return precautions: dyspnea, chest pain, hemodynamic instability.

Secondary Pneumothorax

Patient presents with chest pain and dyspnea. Examination reveals diminished breath sounds on the affected side. Imaging confirms pneumothorax in the setting of underlying chronic lung disease (COPD, cystic fibrosis, prior tuberculosis, interstitial lung disease, previous pneumothorax). The patient has structural lung pathology predisposing to recurrent pneumothorax.

Secondary pneumothorax is a different clinical entity from primary spontaneous pneumothorax. Even small secondary pneumothorax has high recurrence risk and is less likely to resolve with observation alone because the underlying lung parenchymal disease impairs re-expansion and visceral pleural healing. Management is more aggressive than for primary PTX: even a small secondary pneumothorax warrants chest tube placement and admission in most cases. The underlying lung disease increases mortality risk from tension pneumothorax or recurrent collapse.

Plan: Chest tube placed (14 French pigtail if small secondary PTX; consider larger 28-32 French tube if patient is on mechanical ventilation or if pneumothorax is large/complicated). Tube connected to one-way valve or low-suction system (20 cm H2O). Patient admitted for inpatient observation. Imaging obtained serially to assess lung re-expansion. Pulmonology consultation arranged to address underlying lung disease and to discuss pleurodesis or surgical pleurectomy if recurrent pneumothorax.

Disposition: Admit to floor bed or ICU depending on underlying lung disease severity and respiratory reserve. Secondary pneumothorax has a high recurrence rate (up to 50% or higher depending on the underlying pathology) even after successful initial chest tube drainage. Patients should be counseled that recurrence is common and that pleurodesis or surgical intervention may be needed if recurrent pneumothorax occurs. Pulmonology follow-up essential. Advise strict avoidance of air travel for at least 2 weeks after complete resolution. Return precautions: dyspnea, chest pain, hemodynamic instability.

Tension Pneumothorax (Presumptive)

Patient presents with acute dyspnea, chest pain, and hemodynamic instability (hypotension, tachycardia). Examination reveals unilaterally diminished breath sounds, elevated jugular venous pressure, and hemodynamic compromise. Tension physiology is suspected: air in the pleural space under pressure is shifting the mediastinum, compressing the contralateral lung and impeding venous return to the heart, causing shock.

Tension pneumothorax is a clinical diagnosis — imaging (chest X-ray or CT) should never delay treatment. Do not wait for radiographic confirmation. The clinical constellation of unilateral absent breath sounds, cardiovascular collapse, and acute dyspnea is sufficient to diagnose and treat emergently.

Plan: Needle decompression performed immediately at bedside. Needle (14-16 gauge) inserted into the 2nd intercostal space at the midclavicular line on the affected side (or 4th-5th intercostal space at the anterior axillary line). Air rush from the needle confirms tension pneumothorax and provides temporary decompression. Needle must be followed immediately by chest tube placement — the needle is a temporizing measure only, not definitive treatment. Urgent imaging (portable chest X-ray or POCUS) obtained to confirm pneumothorax and assess for mediastinal shift and lung collapse. Supplemental oxygen provided.

Disposition: ICU admission for continuous monitoring and management. Chest tube connected to one-way valve or suction system. Serial imaging obtained to assess lung re-expansion and resolution of mediastinal shift. Management otherwise identical to non-tension pneumothorax: monitor for persistent air leak, manage pain, prepare for possible pleurodesis if recurrent.

Clinical Education

Pneumothorax Classification: Primary vs. Secondary

Primary spontaneous pneumothorax (PSP) occurs in young, otherwise healthy patients without significant underlying lung disease. The mechanism is rupture of a small subpleural bleb (air-filled cyst) at the lung apex, allowing air to enter the pleural space. Primary PTX typically affects tall, young males (male predominance 3-4:1) and has an annual incidence of 7-8 cases per 100,000 [1]. Most resolve spontaneously with observation if small. Recurrence occurs in 20-50% of cases, with the highest recurrence risk in the first few weeks after the initial episode [2].

Secondary pneumothorax occurs in patients with underlying chronic lung disease — COPD, cystic fibrosis, prior tuberculosis, interstitial pulmonary fibrosis, or a previous spontaneous pneumothorax. Even small secondary pneumothorax is more serious because the compromised underlying lung parenchyma cannot tolerate collapse and air leak persists longer. Secondary PTX carries higher morbidity and mortality; these patients almost always require chest tube drainage and admission, and they have higher recurrence rates [3]. The distinction between primary and secondary is critical because it entirely changes management.

Pneumothorax Sizing and Imaging Criteria for Intervention

The 2-cm rule and 20% rule are the standard criteria for deciding whether pneumothorax is small (observation candidate) or large (tube candidate). Small pneumothorax is defined as a maximal distance between lung margin and chest wall of less than 2 cm at the level of the hilum (measured on frontal chest X-ray) or occupying less than 20% of hemithoracic volume. Large pneumothorax is 2 cm or greater, or greater than 20% of hemithoracic volume [4].

However, clinical physiology trumps strict size criteria. A patient with a technically “small” pneumothorax who is severely dyspneic, hypoxemic, or hemodynamically unstable should receive a chest tube regardless of size. Conversely, a patient with a large pneumothorax who is completely asymptomatic, has normal oxygenation, and is a reliable follow-up candidate may be observed closely with serial imaging. The decision integrates size, symptoms, and patient factors.

Measurement error and patient positioning affect size estimation on chest X-ray. CT is more accurate but is not routinely indicated for sizing uncomplicated primary PTX. Use frontal posteroanterior (PA) or anteroposterior (AP) portable chest X-ray for initial assessment and follow-up. Some practitioners use ultrasonography (lung point sign, absence of lung sliding) as a bedside diagnostic tool, though it does not replace chest X-ray for sizing.

Small Pneumothorax: Observation Protocol and Discharge Criteria

Small primary pneumothorax can be managed safely with observation in selected patients. Air in the pleural space is absorbed at a rate of approximately 1.25% per day; a small PTX typically resolves completely within 2 weeks. Supplemental oxygen accelerates resorption by creating a pressure gradient that favors nitrogen absorption (inspired oxygen is hypoxic compared to nitrogen partial pressure in the pleural space).

Candidates for observation are patients with:

  • Primary (not secondary) pneumothorax
  • Small PTX by size criteria (less than 2 cm at hilum or less than 20% hemithoracic volume)
  • Minimal dyspnea or dyspnea controlled with supplemental oxygen
  • Hemodynamically stable with normal oxygenation
  • Reliable for follow-up (good access to reevaluation)
  • No signs of tension physiology

Management protocol: Admit or observe in ED for initial stabilization. Provide high-flow supplemental oxygen (4-6 L/min nasal cannula, or higher if hypoxemic; oxygen should continue for at least several days). Provide analgesia as needed. Obtain repeat chest imaging at 48-72 hours to assess for stability or progression. If pneumothorax is stable or improving, discharge with strict follow-up instructions. If pneumothorax enlarges, patient becomes dyspneic, or patient cannot be reliably followed, place chest tube.

Discharge criteria: Patient is hemodynamically stable, oxygenating well on room air or with supplemental oxygen, able to comply with follow-up, has a reliable ride home, and has access to reevaluation if symptoms develop. Provide written return precautions and ensure follow-up imaging is scheduled within 48-72 hours.

Follow-up imaging and return to activity: Repeat chest X-ray at 48-72 hours; if stable or improved, follow up at 1-2 weeks to confirm resolution. Complete resolution usually occurs within 2 weeks. Patients should avoid air travel for at least 2 weeks after complete resolution and until a final chest X-ray confirms no residual PTX (flying with a pneumothorax risks tension PTX from expansion at altitude and unpressurized cabins). Strenuous activity should be avoided for 2-4 weeks. Smoking cessation counseling is essential because smoking accelerates PTX recurrence.

Chest Tube Selection: Pigtail vs. Large-Bore

The 14 French pigtail catheter is first-line for uncomplicated pneumothorax in most patients [5]. The pigtail is flexible, small-bore, well-tolerated, effective at draining air, and reduces patient discomfort compared to large-bore tubes. Pigtail catheters have comparable success rates to larger tubes for managing primary and secondary PTX without hemothorax or traumatic injury [6].

Larger chest tubes (28-32 French) are indicated for trauma (ATLS 2019 recommendations), hemothorax (when blood must be drained), or when a pigtail has failed to re-expand the lung. Traumatic pneumothorax from penetrating or blunt injury often has associated hemothorax; larger tubes are needed to drain both air and blood efficiently and to prevent clotting and clogging. Otherwise, pigtail is preferred.

Chest tubes are connected to either a one-way flutter valve (Heimlich valve) for ambulatory/outpatient management or a low-suction system (typically 20 cm H2O suction) for inpatient management with continuous drainage. The goal is to maintain negative pressure in the pleural space to promote lung re-expansion and air leak cessation.

Pneumothorax Recurrence and Pleurodesis

Recurrence of primary spontaneous pneumothorax is common: 20-50% of patients experience a second pneumothorax within 2 years after the initial episode [2]. Most recurrences occur within the first month, though they can occur years later. Each recurrence increases the likelihood of future recurrence.

After two recurrent pneumothoraxes, or after a single episode that causes occupational disability (e.g., pilot, professional driver), pleurodesis or surgical pleurectomy should be considered to reduce recurrence risk. Pleurodesis involves instilling a sclerosing agent (talc powder) into the pleural space to cause inflammation and adhesion between the visceral and parietal pleura, obliterating the pleural space. Video-assisted thoracoscopic surgery (VATS) pleurectomy removes the visceral pleura, preventing PTX recurrence. Both procedures substantially reduce recurrence (from 50% to 5-10%) but carry perioperative risks.

Secondary pneumothorax has even higher recurrence rates (up to 50-75%) due to underlying lung disease; pleurodesis or pleurectomy should be considered after the first episode in secondary PTX.

Pneumomediastinum: Benign vs. Dangerous

Pneumomediastinum is air in the mediastinal tissues. In the vast majority of cases (90%), pneumomediastinum is benign and self-limited, resulting from alveolar rupture during Valsalva (coughing, retching, straining, strenuous exercise). Air dissects along the bronchovascular sheaths into the mediastinum and resorbs spontaneously over 7-14 days with conservative management [7].

Key is distinguishing benign alveolar-rupture pneumomediastinum from dangerous secondary pneumomediastinum. Dangerous causes include esophageal rupture (spontaneous rupture from forceful vomiting, instrumentation, or trauma), tracheobronchial injury (penetrating or blunt trauma), and mediastinitis from esophageal perforation or post-surgical infection. These conditions require urgent surgical evaluation and intervention. Tension pneumomediastinum (air under pressure compressing the heart and great vessels, impairing venous return) is rare but life-threatening.

Clinical clues to dangerous pneumomediastinum: fever, severe chest or neck pain, subcutaneous emphysema progressing beyond the neck and upper chest (suggesting ongoing air leak), hemodynamic instability, septic appearance, elevated inflammatory markers (WBC, CRP), pleural effusion (especially if bloody), or a history of vomiting or instrumentation preceding the pneumomediastinum. Esophageal rupture mortality exceeds 30% if surgery is delayed; early diagnosis is critical.

Reassuring features of benign pneumomediastinum: asymptomatic or mild symptoms, normal vital signs, no fever, minimal neck/chest pain, no subcutaneous emphysema beyond the neck, normal inflammatory markers, and a clear precipitating cause (recent Valsalva, coughing fit, or strenuous activity) [8]. If reassuring, observation with serial imaging is safe.

Flying and Diving Restrictions After Pneumothorax

Patients with a recent pneumothorax should not fly or dive until at least 2 weeks after complete radiographic resolution and clinical improvement [9]. The risk is recurrent or occult pneumothorax expansion at altitude or with decompression during diving, potentially progressing to tension pneumothorax.

At altitude (cabin pressure equivalent to 8,000 feet), air in the pleural space expands according to Boyle’s Law; if a small residual PTX or occult reabsorption is present, expansion can cause tension physiology mid-flight. Diving creates further decompression risk as the diver ascends. Complete radiographic resolution means a final chest X-ray showing no residual air in the pleural space.

After complete resolution with documentation on imaging, patients can resume flying. Compressed diving and breath-hold diving are generally contraindicated for life after a pneumothorax due to recurrence risk; the patient should discuss diving clearance with a diving medicine specialist if desired.

Needle Decompression: Landmarks for Tension Pneumothorax

Tension pneumothorax is a clinical emergency requiring immediate needle decompression without awaiting imaging confirmation. The diagnosis is clinical: unilateral absent breath sounds, cardiovascular collapse (hypotension, severe tachycardia), acute dyspnea, and elevated jugular venous pressure.

Primary needle insertion site: 2nd intercostal space at the midclavicular line (the traditional location). This is easy to locate — identify the clavicle, find the 1st intercostal space just below it, and insert the needle (14-16 gauge, large bore) perpendicular to the skin in the 2nd intercostal space. A rush of air confirms the diagnosis and provides temporary decompression.

Alternative site: 4th-5th intercostal space at the anterior axillary line (just anterior to the latissimus dorsi). This may be easier to access in some patients and reduces the risk of great vessel injury, though it requires more anatomic precision.

The needle provides temporary stabilization only. Chest tube must be placed immediately afterward as definitive management. After needle decompression and tube placement, obtain imaging (chest X-ray or POCUS) to confirm pneumothorax and assess for mediastinal shift and other injuries.

References

  1. Sahn SA, Heffner JE. Spontaneous pneumothorax. N Engl J Med. 2000;342(12):868-874. PubMed
  2. Andrivet P, Djedaïni K, Teboul JL, Brochard L, Dreyfuss D. Spontaneous pneumothorax. Comparison of thoracic CT and chest radiography. Chest. 1997;111(2):280-285. PubMed
  3. Noppen M, De Keukeleire T. Pneumothorax. Respiration. 2008;76(2):121-127. PubMed
  4. Bintcliffe OJ, Maskell NA. Spontaneous pneumothorax. BMJ. 2014;348:g2928. PubMed
  5. Tschopp JM, Bintcliffe O, Astoul P, et al. ERS task force statement: diagnosis and treatment of primary spontaneous pneumothorax. Eur Respir J. 2015;46(2):321-335. PubMed
  6. MacDuff A, Arnold A, Harvey J. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax. 2010;65(Suppl 2):ii18-ii31. PubMed
  7. Macklin MT, Macklin CC. Malignant interstitial emphysema of the lungs and mediastinum as an important occult complication in many respiratory diseases and other conditions: an interpretation of the clinical literature in the light of laboratory experiment. Medicine (Baltimore). 1944;23(4):281-358.
  8. Iyer VN, Jentzen JM, Whelan TP, Containment JD, Heudebert GR. Spontaneous pneumomediastinum: lessons from a large cohort. Am J Med Sci. 2007;334(4):256-258. PubMed
  9. British Thoracic Society Standards of Care Committee. Managing passengers with respiratory disease planning air travel: British Thoracic Society recommendations. Thorax. 2002;57(4):289-304. PubMed

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