Pneumothorax is a medical lung for collapsed lungs. It refers to the presence of gas or air in the pleural cavity, which is the space flanked by parietal pleura and visceral of the lungs, hence impairing oxygenation. Air enters the pleural space due to an open injury in the chest or a tear in lung tissues, interfering with the pressure that maintains the lungs inflated. Clinical results vary according to the magnitude of lung collapse, especially on the affected side. Severe pneumothorax compromises hemodynamic stability while causing shifts in the mediastinum. This causes air to get into the intrapleural space through lung parenchyma or chest wall.
Pleura are thin membranes surrounding the lungs. Between parietal pleura and visceral pleura is a small amount of fluid known as the pleural fluid, which provides surface tension that maintains the inflation of lungs while also functioning lubricant preventing friction between the ribcage and the lungs. The fluid also connects the pleural tissue by providing a pull between the two pleural layers, leading to negative pressure, which is around 5mmHg lower than the pressure in the alveolar. This provides pressure in the chest, which maintains breathing while preventing the lungs from collapsing.
The space between the innner side of the chest and the outer part of the lungs is called the pleural space or cavity. The pressure contained by this region is the antra pleural pressure and is often less compared to the pressure contained by the lungs known as the intrapulmonary pressure. Differences between intrapulmonary pressure and intrapleural pressure are transpulmonary pressure. Intrapleural pressure around the lungs creates a vacuum that prevents the lungs from collapsing. The difference in the pressure enhances ventilation by facilitating the constant lung opening.