What is a pneumothorax?
The presence of air in the pleural space, between the parietal and visceral pleura.
How does a pneumothorax cause lung collapse?
Air entering the pleural cavity disrupts the normal negative pleural pressure, allowing the lung to recoil and collapse
What are the two main mechanisms by which air enters the pleural space?
- Trauma causing communication through the chest wall
- Rupture of the visceral pleura
What is the normal pleural pressure?
Approximately –5 cmH₂O.
What maintains negative pleural pressure?
- Hydrostatic pressure
- Oncotic pressure
- Pulmonary surfactant reducing friction and maintaining lung expansion
Why is negative pleural pressure important?
Keeps the lungs expanded against the chest wall during respiration
What happens when the pleural space communicates with alveoli or the atmosphere?
Air fills the pleural space → pressure equalises → lung collapses to equilibrium.
How does pneumothorax affect oxygenation?
Reduced lung volume → ↓ vital capacity → ↓ alveolar oxygen partial pressure → hypoxia
What are common symptoms of pneumothorax?
Sudden chest pain, dyspnoea, tachypnoea, tachycardia, hypoxia.
What signs suggest a tension pneumothorax?
- Severe hypotension (obstructive shock)
- Distended neck veins (↑ central venous pressure)
- Tracheal deviation (late sign)
- Cyanosis
- Respiratory distress
What is a spontaneous pneumothorax?
Pneumothorax occurring without trauma, usually due to rupture of bullae or blebs.
What are bullae/blebs?
Air‑filled spaces from microscopic alveolar leaks that can rupture into the pleural cavity
Who is most at risk of PSP?
Tall, thin young adults; smokers/vapers; individuals with increased apical shear forces.
What is the underlying mechanism in PSP?
Inflammation and oxidative stress in small airways → bleb formation → rupture.
What conditions predispose to SSP?
- COPD (most common)
- Tuberculosis
- Sarcoidosis
- Cystic fibrosis
- Lung malignancy
- Idiopathic pulmonary fibrosis
- Pneumocystis jiroveci pneumonia
What causes traumatic pneumothorax?
Blunt or penetrating chest trauma creating a pleural defect.
What is an iatrogenic pneumothorax?
Pneumothorax caused by medical procedures (e.g., mechanical ventilation, lung biopsy, thoracentesis).
What is a tension pneumothorax?
A life‑threatening condition where a one‑way valve allows air into the pleural space but prevents exit → rising intrathoracic pressure → cardiovascular collapse.
Where is tension pneumothorax most commonly seen?
ICU patients on positive‑pressure ventilation.
What is the hallmark of pneumothorax on a physiological level?
Loss of negative pleural pressure → lung collapse
What distinguishes PSP from SSP?
- PSP: No underlying lung disease
- SSP: Occurs in patients with pre‑existing lung pathology
What makes tension pneumothorax a medical emergency?
Rapid rise in intrathoracic pressure → obstructive shock → risk of death without immediate decompression.
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Genetic testing: cystic fibrosis30
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Pulmonary surfactants29
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Altitude physiology24
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COPD38
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Lung cancer39
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Controlled Drugs34
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Spirometry38
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Inhaler technique30
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Investigating patient safety incidents29
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Environmental pollution48
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Smoking and vaping50
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Chemistry of large molecule therapeutics44
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Introduction to antimicrobial resistance67
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Pseudomonas42
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Mycoplasma32
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Legionella45
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Tuberculosis44
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Obstructive Sleep Apnoea38
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Medical gases18
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Altitude sickness35
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Pneumothorax22
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Cystic fibrosis43
