Pneumothorax (Spontaneous and Tension)

Risk factors

• PSP: tall, thin males age 15-34, smoking (>20× risk), family history, Marfan syndrome
• SSP: COPD (most common), asthma, cystic fibrosis, TB, Pneumocystis pneumonia, lung cancer, ILD, LAM, Birt-Hogg-Dubé syndrome
• Traumatic: blunt or penetrating chest trauma, rib fracture
• Iatrogenic: central line placement, thoracentesis, lung biopsy, mechanical ventilation (barotrauma), CPR
• Catamenial (rare): pleural endometriosis, recurs with menses

Pathophysiology

Disruption of visceral pleura (rupture of subpleural bleb in PSP) allows air to enter pleural space → loss of negative intrapleural pressure → ipsilateral lung collapse. Tension physiology occurs when a one-way valve traps air with each breath, increasing intrathoracic pressure, displacing mediastinum, compressing venous return → obstructive shock.

Clinical presentation

Differential diagnosis

• Pulmonary embolism — Pleuritic pain, hypoxia, normal CXR; D-dimer, CTPA; preserved breath sounds bilaterally
• Acute coronary syndrome — Substernal pressure, ECG changes, troponin rise
• Pneumonia / pleurisy — Fever, infiltrate on CXR, productive cough
• Musculoskeletal chest pain — Reproducible with palpation; normal exam and vitals
• Pericarditis / tamponade — Pleuritic pain improved leaning forward, friction rub, ECG findings; pericardial effusion on echo
• Aortic dissection — Tearing pain, BP differential, widened mediastinum on CXR
• Large bulla mimicking pneumothorax — Pre-existing imaging important; CT can distinguish — avoid chest tube if bulla

Diagnostic workup

Diagnostic algorithm

flowchart TD
  A[Suspected pneumothorax] --> B{Hemodynamic<br/>compromise?}
  B -->|Yes| C[TENSION PTX<br/>Needle decompress<br/>4-5th ICS AAL/MAL]
  C --> D[Tube thoracostomy]
  B -->|No| E[CXR / ultrasound]
  E --> F{Size and<br/>symptoms}
  F -->|Small PSP<br/>asymptomatic| G[Observe + O2<br/>± outpatient]
  F -->|Large PSP<br/>or symptomatic| H[Aspiration or<br/>small-bore chest tube]
  F -->|SSP| I[Chest tube<br/>+ admit]
  G --> J[Recurrence?]
  H --> J
  I --> J
  J -->|2nd event or<br/>persistent leak| K[VATS + pleurodesis]

Treatment

Complications

• Tension pneumothorax with obstructive shock and cardiac arrest
• Persistent air leak, bronchopleural fistula
• Re-expansion pulmonary edema (rapid evacuation of large/chronic PTX)
• Recurrence — 30-50% after first PSP without intervention
• Hemopneumothorax from torn pleural adhesion

PANCE pearls

• Tension pneumothorax is a CLINICAL diagnosis; never delay decompression for a CXR — needle decompress immediately, then tube thoracostomy.
• ATLS now recommends needle decompression at 4th-5th intercostal space anterior or mid-axillary line (thinner chest wall) rather than the older 2nd ICS midclavicular site.
• High-flow oxygen accelerates PSP reabsorption ~4-fold via nitrogen washout — use even in observation cases.
• Beware re-expansion pulmonary edema after rapid drainage of large/chronic PTX or pleural effusion — drain slowly, clamp if cough/desaturation.
• Recurrence after first PSP is 30-50%; recurrence after a second event approaches 80% — pleurodesis indicated after the second event (or first contralateral, bilateral, or persistent air leak).

References

• BTS 2023 — BTS Clinical Statement on Spontaneous Pneumothorax (Roberts et al., Thorax 2023)
• ACCP — Management of Spontaneous Pneumothorax: An American College of Chest Physicians Delphi Consensus Statement (Baumann et al., Chest 2001)
• PSP Trial — Conservative vs Interventional Treatment for Spontaneous Pneumothorax (Brown et al., NEJM 2020)
• ATLS 10th Edition — Advanced Trauma Life Support, 10th Ed., American College of Surgeons Committee on Trauma (2018)