Pneumothorax and Pleural Effusion Quiz

See Pneumothorax. Option D is correct because a pneumothorax is defined as the presence of air in the pleural space. The pleural space is the thin potential space between the visceral pleura (the membrane on the lung surface) and the parietal pleura (the membrane lining the chest wall), and normally it holds only a tiny amount of fluid. It sits at negative pressure, because the lung's elastic recoil pulls inward while the chest wall springs outward, and this suction keeps the lung expanded against the chest wall. When air enters the space, the negative pressure is lost and the lung partly or completely collapses. Air may come from the lung (a spontaneous leak or a ruptured bleb, a small air-filled blister on the lung surface), from the outside through a chest wound, or during a procedure. The classic presentation is sudden pleuritic chest pain, which is sharp and worse on deep breathing, with breathlessness. Remember: pneumo means air and thorax means chest, so a pneumothorax is air in the chest outside the lung.

• Definition: Air in the pleural space.
• Normal state: The pleural space is at negative pressure, which keeps the lung expanded.
• Effect: When air enters, the negative pressure is lost and the lung partly or completely collapses.

To keep these apart, ask where the abnormal material is and what it is: air in the pleural space is a pneumothorax, fluid in the pleural space is an effusion, fluid in the alveoli is oedema or pneumonia, and a collapsed lung from a blocked airway is atelectasis.