What causes atelectasis?

Pulmonary atelectasis occurs when the alveoli in a lung or a portion of a lung collapse. This can happen for a variety of reasons, including:

- _Obstruction of the bronchus by a foreign object, tumor, mucus plug, or blood clot._

- _Pressure on the lung tissue from a tumor or enlarged lymph nodes._

- _Scar tissue from previous lung infections or injuries._

- _Neurological conditions that affect the muscles responsible for breathing._

- _General anesthesia._

- _Prolonged bed rest._

- _Smoking._

- _Certain medical conditions, such as cystic fibrosis and asthma._

Atelectasis can also occur as a complication of surgery or other medical procedures.