Clinical exam · Respiratory system
Pneumothorax syndrome !
- Syndrome
Air between the lung and the chest wall: the lung collapses, that side sounds hollow and breathing cannot be heard.
Updated 2026-11-01
See it in 3D: Pleura · Trachea
What it is
Pneumothorax is air in the pleural space, which removes the negative pressure and lets the lung collapse. It may be spontaneous (primary in tall, thin young people, or secondary to lung disease), traumatic or iatrogenic. Tension pneumothorax is an emergency diagnosed clinically: it blocks venous return and causes shock.
Key findings
- A small pneumothorax can give an almost normal exam.
- Tracheal deviation is a late sign of tension; hypotension and distress come earlier.
Pathophysiology
- Negative pleural pressure keeps the lung against the wall; when air enters, the lung recoils by its own elasticity.
- Air between lung and wall damps vibration and sound and makes percussion hyperresonant.
- In tension, a valve effect lets air in on each breath with no way out: pressure rises, shifts the mediastinum and compresses the venae cavae.
- Primary pneumothorax usually comes from rupture of small subpleural blebs at the apices.
| Inspection | Palpation (fremitus) | Percussion | Auscultation |
|---|---|---|---|
| Simple: side moves little, expansion ↓; trachea midline | Reduced or absent fremitus | Hyperresonance or tympany | Reduced or absent breath sounds; voice absent |
| Tension: side full, neck veins distended; trachea to the opposite side | Absent fremitus | Tympany | Absent breath sounds; tachycardia and hypotension |
Common causes
- Primary spontaneous, in young people with no known lung disease.
- Secondary spontaneous: COPD, asthma, tuberculosis, cystic fibrosis, Pneumocystis pneumonia.
- Traumatic: rib fractures, penetrating wounds, flail chest.
- Iatrogenic: central venous catheter, biopsy, thoracentesis, positive-pressure ventilation.
Tests that confirm it
- Chest radiograph: a visceral pleural line with no lung markings beyond it.
- Lung ultrasound: absent lung sliding and a lung point, quick at the bedside.
- CT in doubtful cases or to look for blebs.
Test yourself
Think of the answer, then tap the question to see it.
Which percussion and auscultation findings mark a pneumothorax?
Hyperresonance or tympany with reduced or absent breath sounds and absent fremitus on the affected side.
Which way does the trachea shift in tension pneumothorax?
Away from the side of the pneumothorax.
Why does tension pneumothorax cause hypotension?
High intrathoracic pressure shifts the mediastinum and compresses the venae cavae, cutting venous return (obstructive shock).
What is the typical patient with primary spontaneous pneumothorax?
A young, tall, thin man, often a smoker, with no known lung disease.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- The pleuropulmonary syndromes: the comparison table to know
- Chest percussion: resonance, dullness and hyperresonance
- Pleural effusion syndrome
- Respiratory distress and respiratory failure: the signs
- Jugular venous pressure and the venous pulse
Related conditions
Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.
Sources: Collapsed lung (pneumothorax) (MedlinePlus, U.S. National Library of Medicine, 2024); Breath sounds: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2024).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.