Key Facts

Pneumothorax is the presence of air in the pleural space causing partial or complete lung collapse. Management ranges from observation to emergency intervention depending on the type, size, and clinical impact.

Epidemiology

PSP incidence: approximately 9-24 per 100,000 per year (men); 1.5-6 per 100,000 (women). Smoking increases risk 20-fold. SSP incidence increases with age and severity of underlying lung disease. Tension pneumothorax occurs in trauma, ventilated patients, and following procedures.

Aetiology

Primary (no underlying lung disease):

• Rupture of subpleural blebs (apical) — tall, thin habitus, smoking, connective tissue disorders (Marfan's, Ehlers-Danlos)

Secondary (underlying lung disease):

• COPD (most common cause of SSP), asthma, TB, interstitial lung disease, Pneumocystis jirovecii (HIV), lung cancer, cystic fibrosis

Traumatic:

• Blunt or penetrating chest trauma, rib fractures
• Iatrogenic: Central line insertion (subclavian > IJV), lung biopsy, mechanical ventilation (barotrauma), thoracentesis

Pathophysiology

Air enters the pleural space through a defect in the visceral pleura (spontaneous) or chest wall (trauma). This disrupts the normal negative intrapleural pressure, causing lung collapse. In tension pneumothorax, a one-way valve mechanism allows air in but not out, progressively increasing intrapleural pressure, compressing the mediastinum, and impairing venous return — causing cardiovascular collapse.

Symptoms

• Sudden-onset pleuritic chest pain (ipsilateral)
• Dyspnoea (proportional to size and underlying lung function)
• May be asymptomatic in small PSP

Signs

• Reduced breath sounds on affected side
• Hyper-resonance to percussion
• Reduced chest expansion
• Tracheal deviation AWAY from affected side (tension)

Tension Pneumothorax

• All of the above PLUS:
• Tachycardia, hypotension, distended neck veins
• Tracheal deviation (late sign)
• Cardiac arrest (PEA)
• Clinical diagnosis — do NOT wait for CXR

Red Flags

• Bilateral pneumothorax — life-threatening; both sides need drainage
• Tension pneumothorax — immediate decompression
• SSP in elderly/COPD — more dangerous than PSP; lower threshold for intervention
• Haemopneumothorax — blood AND air; requires chest drain and possible surgery

Bedside

• CXR (PA erect): First-line diagnostic investigation — visible visceral pleural edge, absent lung markings peripheral to this
• Size estimation: >2cm at hilum level on PA CXR = 'large' (BTS)
• SpO2: May be normal in PSP; reduced in SSP

Bloods

• ABG: If hypoxic or SSP — assess PaO2, PaCO2
• FBC: Baseline

Imaging

• CT chest: If diagnostic uncertainty, complex pneumothorax, or planning surgical intervention
• USS: Can detect pneumothorax (absent lung sliding) — increasingly used in trauma (E-FAST)

Special Tests

• Serial CXR: After aspiration or drain; before and after clamping/removal

Tension Pneumothorax (Emergency)

• Needle decompression: 14-16G cannula, 2nd intercostal space, mid-clavicular line, affected side
• Then chest drain: Large-bore (28-32Fr) in safe triangle (4th-5th ICS, mid-axillary line)

Primary Spontaneous Pneumothorax (BTS Algorithm)

• Small (<2cm) and asymptomatic: Observe 4-6h; discharge if stable CXR; review 2-4 weeks
• Large (≥2cm) or symptomatic: Needle aspiration first (16-18G, 2nd ICS MCL; aspirate up to 2.5L)
  • If aspiration successful (lung re-expanded, <2cm residual): Observe, discharge with follow-up
  • If aspiration fails: Insert small-bore chest drain (12-16Fr, Seldinger technique)

Secondary Spontaneous Pneumothorax

• Small (<2cm) and minimal symptoms: Admit, observe, high-flow O2 (enhances air reabsorption)
• Large (≥2cm) or breathless: Chest drain (small-bore or large-bore)
• All SSP: Admit for observation due to higher risk

Pharmacological

• Analgesia: Paracetamol ± NSAIDs (unless contraindicated); opioids for severe pain (use cautiously — respiratory depression)
• Supplemental oxygen: Accelerates pneumothorax resolution (~4× faster with high-flow O2)

Surgical/Interventional

• Video-assisted thoracoscopic surgery (VATS): For persistent air leak (>5 days), second ipsilateral PSP, first contralateral PSP, bilateral pneumothorax, or haemothorax
• Pleurodesis: Chemical (talc) or surgical — prevents recurrence; ~95% success rate
• Pleurectomy: Definitive surgery — parietal pleura stripped; very low recurrence

Referral Criteria

• Second ipsilateral PSP — thoracic surgery for VATS/pleurodesis
• Persistent air leak >5 days — thoracic surgery
• Bilateral pneumothorax — both sides require drainage; surgical referral
• SSP requiring drain — respiratory and thoracic surgery input

• Recurrence after first PSP: ~30% within 2 years
• Recurrence after second: ~60%
• Post-pleurodesis recurrence: ~5%
• Smoking cessation: Reduces recurrence risk significantly
• Tension pneumothorax: Fatal without treatment; excellent prognosis if decompressed promptly
• SSP: Higher morbidity and mortality than PSP due to underlying lung disease

BTS Pneumothorax Management Algorithm (Simplified)

Safe Triangle for Chest Drain Insertion