An obstructed airway prevents air from reaching the lung region beyond the blockage. As the trapped air is lost, that region cannot maintain its volume, so ventilation falls and gas exchange becomes less effective. Mucus plugging is one clinically relevant example, particularly after surgery, when shallow breathing can make airway clearance more difficult.
Surfactant helps alveoli remain open by supporting their stability. When surfactant is inadequate, alveoli are more likely to close, reducing the amount of ventilated lung tissue. This mechanism differs from collapse caused by an airway blockage or by pressure from air or fluid in the pleural space, although each can impair oxygen exchange.
Air or fluid in the pleural space can exert external pressure on adjacent lung tissue. That compression limits expansion and may reduce the air volume available for ventilation in the affected region. Because the mechanism is external rather than an airway blockage, clinical management focuses on identifying and addressing the pleural pressure contributing to the collapse.
Collapsed or poorly ventilated lung regions contribute less effectively to gas exchange. If enough lung tissue is affected, the body may receive less oxygen, producing possible oxygen deficiency. The degree of impact depends on the extent and cause of the collapse, which is why clinical assessment must connect observed findings with imaging and the underlying condition.
Assessment combines physical examination with chest imaging. The examination provides clinical findings that can prompt further evaluation, while imaging helps identify affected lung regions and supports investigation of possible causes. This combined approach is useful because treatment depends on whether the problem reflects airway obstruction, pleural pressure, shallow breathing, or another contributing clinical circumstance.
Management is selected according to the cause and may include airway-clearance measures, breathing exercises, oxygen support, or treatment directed at pleural pressure. After surgery, encouraging effective breathing and addressing mucus plugging may be particularly relevant. The clinical objective is to improve ventilation or correct the factor preventing the affected lung region from remaining open.