Pneumothorax Flashcards
What is a pneumothorax?
Air in the pleural space (the potential space between visceral and parietal pleura). Other variants depend on the substance in the pleural space e.g., blood is haemothorax and lymph is chylothorax.
What is a tension pneumothorax?
Emergency when a functional valve lets air into the pleural space during inspiration, but not leave during expiration – this is associated with mediastinal shift.
What is the aetiology of pneumothorax? (x3 categories)
- SPONTANEOUS: tall, thin males probably caused by rupture of subpleural bleb
- SECONDARY: pre-existing lung disease (COPD, asthma, TB, pneumonia, lung carcinoma, cystic fibrosis, diffuse lung disease)
- TRAUMATIC: penetrating injury to chest, often iatrogenic causes such as subclavian or jugular venous cannulation, thoracocentesis, pleural or lung biopsy, or positive pressure assisted ventilation
What are the risk factors of pneumothorax?
Collage disorders e.g., Marfan’s syndrome and Ehlers-Danlos syndrome, smoking,
What is the epidemiology of pneumothorax: Incidence? Age? Gender?
Annual incidence of spontaneous pneumothorax is 9 in 100 000. Mainly affects 20-40-year-olds. Four times more common in males.
What is the pathophysiology of pneumothorax?
Normally, the alveolar pressure is greater than the intrapleural pressure, while the intrapleural pressure is less than atmospheric pressure. Therefore, if a communication develops between an alveolus and the pleural space, or between the atmosphere and the pleural space, gases will follow the pressure gradient and flow into the pleural space. This flow will continue until the pressure gradient no longer exists or the abnormal communication has been sealed.
What is the pathophysiology of tension pneumothorax?
Occurs when the intrapleural pressure exceeds atmospheric pressure, especially during expiration, and results from a ball valve mechanism that promotes inspiratory accumulation of pleural gases. The build-up of pressure within the pleural space eventually results in hypoxaemia and respiratory failure from compression of the lung.
What are the symptoms of pneumothorax? (x2 +2 tension)
- May be asymptomatic if small
- Sudden onset breathlessness
- Sudden onset pleuritic chest pain, especially on inspiration. Some may also experience shoulder tip pain
- Distress with rapid shallow breathing if tension pneumothorax
- Sweating is a feature of tension pneumothorax
What are the signs of pneumothorax? (x4 and x6)
- Absent if small
- Signs of respiratory distress with reduced expansion, ipsilateral hyper-resonance to percussion, decreased breath sounds, hypoxia
- Tension: severe respiratory distress (4 signs above), tachycardia, hypotension, cyanosis, distended neck veins, tracheal deviation away from side of pneumothorax
How does pneumothorax present on CXR?
Dark area of film where lung markings do not extend to. Fluid level may be seen where blood is present. In small pneumothoraxes, expiratory films (CXR taken on expiration; note that CXR usually taken on inspiration) may make it more prominent.
What are the other investigations for pneumothorax? (x1)
ABG: determine if there is hypoxaemia, particularly in secondary disease. Respiratory alkalosis is common finding.
How is tension pneumothorax managed? (x3)
- EMERGENCY.
- Immediate decompression: Insert large-bore needle into second intercostal space, MCL, on side of pneumothorax to relieve pressure (remember, pressure builds very high in tension pneumothorax, so need to relieve pressure ASAP)
- Maximum oxygen
- Insert chest drain soon after
How does size of pneumothorax determine management?
Small pneumothorax (less than 2cm lung-pleural margin) mandates more conservative management. Moderate pneumothorax (larger than 2cm) requires medical management.
How is small pneumothorax managed?
Observation for 4-6 hours, supplemental oxygen if necessary, and analgesics if required.
When is small pneumothorax medically managed?
If associated with breathlessness.
