deflation

Deflation of the lungs, also known as atelectasis, refers to the incomplete expansion or collapse of lung tissue. This can occur in infants due to a lack of surfactant, causing alveoli (air sacs) to remain collapsed. In adults, atelectasis can be caused by external pressure on the lungs, such as from tumors or an enlarged heart (compressive atelectasis). It can also result from blockages in the bronchial passageways, like foreign objects or mucus plugs, which prevent air from reaching the alveoli (obstructive atelectasis). In extreme cases, symptoms include low blood oxygen and, if prolonged, can lead to irreversible scarring and loss of respiratory function. Thoracic squeeze, a related phenomenon, is the compression of the lungs due to increased external pressure, often experienced during breath-holding dives.12