Pneumothorax
Air enters the pleural space and abolishes the negative pressure that normally holds the lung expanded against the chest wall, so the lung collapses inward under its own elastic recoil, and if the air entry becomes one-way the resulting pressure buildup can compress the heart and great vessels, a time-critical emergency.
In a nutshell
Air entering the pleural space abolishes the negative pressure holding the lung against the chest wall, so the lung collapses under its own elastic recoil. If the leak acts as a one-way valve, pressure builds progressively, shifting the mediastinum and compressing the heart and great veins (tension pneumothorax), which is a clinical diagnosis treated immediately, before imaging.
Classic presentation
Sudden pleuritic chest pain and breathlessness in a young tall thin adult, or a patient with underlying lung disease or recent trauma, with reduced breath sounds and hyper-resonance on one side.
Key points
- The lung is held expanded by negative pleural pressure, not muscular effort: losing that negative pressure lets the lung's own elastic recoil collapse it.
Educational content pending clinical review. Not medical advice.