Pneumothorax - Pleurae Flashcards
1
Q
What are the pleurae?
A
A pair of serous membranes that exist between the lungs and the chest wall - visceral and pleural.
2
Q
What does each pleura line?
A
Visceral - each lung.
Parietal - thoracic cavity, enclosing the chest, diaphragm and mediastinum within.
3
Q
What is the pleural cavity?
A
The space between the visceral and parietal pleurae - contains pleural fluid.
4
Q
Describe the force inside the pleural cavity.
A
Alveolar pressure is greater than intrapleural pressure (negative/sub-atomospheric - collapsing force).
5
Q
What happens to the force in a simple pneumothorax?
A
The pressure gradient allows gases to move from the alveolus into the atmosphere - the thoracic cavity enlarges but the lung becomes smaller.
6
Q
What is the mechanism of a tension pneumothorax? (3)
A
- A one-way valvular mechanism develops where air can be sucked into the pleural space during inspiration but not expelled during expiration.
- Intrapleural pressure remains positive throughout breathing.
- With each breath, the lung deflates further, the mediastinum shifts, the venous return to the heart decreases, cardiorespiratory embarassment increases.
