Pneumothorax
Accumulation of air in the pleural space causing partial or complete lung collapse. Classified as primary spontaneous (no underlying disease), secondary (underlying lung disease), or traumatic.
Key Facts
Primary spontaneous: tall thin young males, smokers; rupture of subpleural blebs; no underlying lung disease Secondary spontaneous: underlying lung disease (COPD most common); higher morbidity/mortality BTS guideline: primary >2cm rim on CXR or symptomatic → needle aspiration first; if fails → chest drain Secondary: all >2cm or symptomatic → chest drain (intercostal drain with underwater seal, NOT Heimlich valve) Tension pneumothorax: medical emergency; immediate needle decompression (2nd intercostal space MCL) then chest drain Recurrence rate: ~30% after first primary spontaneous; ~50% after second episode Definitive management: VATS pleurectomy or pleurodesis after second ipsilateral or first bilateral pneumothorax Flying: avoid for 1 week after confirmed CXR resolution; diving is permanently contraindicated unless bilateral surgical pleurectomy
Overview
Key Facts
A pneumothorax occurs when air enters the pleural space, disrupting the negative intrapleural pressure and causing partial or complete lung collapse. Management depends on the type (primary vs secondary), size, and clinical stability.
Epidemiology
- Primary spontaneous: incidence ~18-28 per 100,000 in males, ~1.2-6 per 100,000 in females
- Peak incidence: young men aged 20-30
- Secondary spontaneous: incidence increases with age and COPD severity
- Male:female ratio ~3:1 (primary); more equal in secondary
Aetiology
Primary spontaneous:
- Rupture of subpleural apical blebs/bullae
- Risk factors: tall thin body habitus, smoking, cannabis use, family history, Marfan syndrome, homocystinuria
Secondary spontaneous:
- COPD (most common)
- Asthma, cystic fibrosis, TB, Pneumocystis pneumonia
- Interstitial lung disease, LAM (lymphangioleiomyomatosis)
- Lung cancer, mesothelioma
- Catamenial pneumothorax (associated with endometriosis, right-sided, menstrual)
Traumatic:
- Penetrating/blunt chest trauma
- Iatrogenic: central line insertion, thoracentesis, lung biopsy, mechanical ventilation
Pathophysiology
- Air enters pleural space through visceral pleura defect (spontaneous) or chest wall breach (traumatic)
- Loss of negative intrapleural pressure → lung collapse
- Mediastinal shift occurs with large pneumothorax
- Tension pneumothorax: one-way valve mechanism → progressive air accumulation → mediastinal shift → cardiovascular compromise
Clinical Presentation
Typical Presentation
- Sudden onset unilateral pleuritic chest pain
- Breathlessness (proportional to size and underlying lung function)
- May be relatively asymptomatic in small primary pneumothorax
Clinical Signs
- Reduced chest expansion on affected side
- Hyperresonant percussion
- Reduced or absent breath sounds
- Tracheal deviation away from affected side (large/tension)
- Tachycardia
Tension Pneumothorax
- Severe respiratory distress
- Tracheal deviation to contralateral side
- Distended neck veins
- Hypotension, tachycardia
- Cardiovascular collapse
- Absent breath sounds on affected side
- Clinical diagnosis — do not delay for CXR
Red Flags
- Haemodynamic compromise (tension pneumothorax)
- Bilateral pneumothorax
- Secondary pneumothorax in severe COPD
- Large pneumothorax (>2cm rim on CXR)
- Increasing breathlessness after initial management
- Pneumothorax on mechanical ventilation
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| Pulmonary embolism | Pleuritic pain, dyspnoea, VTE risk factors | CTPA, D-dimer |
| Acute coronary syndrome | Central chest pain, ECG changes, troponin | ECG, troponin |
| Pleurisy/pleural effusion | Pleuritic pain, reduced breath sounds, dull percussion | CXR, USS |
| Musculoskeletal pain | Reproducible on palpation, no systemic features | Clinical |
| Pericarditis | Sharp pain, sitting forward relief, saddle ST | ECG, echo |
| Rib fracture | Trauma history, point tenderness | CXR |
| Oesophageal rupture (Boerhaave) | Post-vomiting, surgical emphysema, pneumomediastinum | CXR, CT |
Diagnosis / Investigation
Bedside
- CXR (PA, erect, in inspiration): visible visceral pleural line, absent lung markings peripherally
- Size estimation: BTS uses distance from chest wall to lung edge at hilar level (>2cm = large)
- Pulse oximetry: SpO₂
- ABG: if secondary pneumothorax or SpO₂ <92%
Bloods
- FBC, U&Es: baseline (especially if intervention planned)
- Coagulation: pre-procedure
Imaging
- CT chest: if diagnostic uncertainty, suspected bullous disease, recurrent pneumothorax, pre-surgical planning
- USS (point-of-care): useful in trauma — absent lung sliding, absent comet tail artefacts, lung point sign
Special Tests
- Post-aspiration/drain CXR: confirm re-expansion
- Alpha-1 antitrypsin level: if bullous emphysema in young patient
- HRCT: assess for underlying cause in secondary pneumothorax
Management
Non-pharmacological
- Conservative observation: primary spontaneous <2cm rim, minimal symptoms — observe 2-4 hours, repeat CXR, discharge with follow-up CXR
- High-flow oxygen 10L/min via non-rebreathe mask accelerates pneumothorax resolution (increases absorption rate 4-fold)
- Analgesia (paracetamol, NSAIDs)
Pharmacological
- Analgesia for procedural pain
- Antibiotics only if secondary infection
Surgical/Interventional
BTS Management Algorithm:
Primary spontaneous pneumothorax:
- <2cm rim + minimal symptoms → conservative + follow-up CXR
- ≥2cm rim or breathless → needle aspiration (14-16G, 2nd ICS MCL); if fails (re-accumulates/aspirate >2.5L) → chest drain (small bore 8-14Fr)
Secondary spontaneous pneumothorax:
- <1cm rim + minimal symptoms → observe with oxygen, admit
- 1-2cm rim → needle aspiration; if fails → chest drain
-
2cm rim or breathless → chest drain (small bore, Seldinger technique)
Chest drain management:
- Connect to underwater seal
- Never clamp a bubbling drain
- Remove when lung re-expanded and no air leak for >24 hours
- Post-removal CXR
Tension pneumothorax:
- Immediate needle decompression: 14G cannula, 2nd ICS MCL (or 4th/5th ICS mid-axillary line)
- Followed by chest drain insertion
Definitive (surgical):
- VATS pleurectomy/pleurodesis: after 2nd ipsilateral, 1st bilateral/contralateral, persistent air leak >5 days, or high-risk occupation (pilot, diver)
- Chemical pleurodesis (talc) via chest drain if surgery not possible
Referral Criteria
- All secondary pneumothoraces: respiratory admission
- Persistent air leak >48 hours: thoracic surgery referral
- Recurrent pneumothorax: surgical referral for VATS
- Bilateral pneumothorax: urgent referral
- Catamenial pneumothorax: gynaecology + respiratory
Prognosis
- Primary spontaneous: recurrence ~30% after first episode; ~50% after second; ~80% after third
- Secondary spontaneous: higher morbidity/mortality; in-hospital mortality ~10% for COPD patients
- VATS pleurectomy reduces recurrence to ~1-5%
- Chemical pleurodesis recurrence: ~10-20%
- Tension pneumothorax: fatal if untreated; excellent outcome if recognised and treated promptly
- Return to normal activities: 2-4 weeks after resolution
- Flying: avoid until confirmed CXR resolution + 1 week
- Diving: permanent contraindication unless bilateral surgical pleurectomy with normal CT
Other Relevant Information
BTS Size Classification
| Size | Description |
|---|---|
| Small | <2cm rim at hilar level on CXR |
| Large | ≥2cm rim at hilar level on CXR |
Pneumothorax Management Summary (BTS)
| Type | Small | Large/Symptomatic |
|---|---|---|
| Primary | Observe, follow-up CXR | Aspiration → drain if fails |
| Secondary | Admit, oxygen, aspiration | Chest drain |
| Tension | — | Immediate decompression + drain |
Advice on Discharge
| Activity | Advice |
|---|---|
| Smoking | Cessation essential (reduces recurrence) |
| Flying | Avoid until 1 week after CXR confirms resolution |
| Diving | Permanently contraindicated (unless bilateral surgical pleurectomy) |
| Follow-up | CXR at 2-4 weeks |