The first thing to understand is the cause of pulmonary atelectasis in babies. There are many causes of atelectasis, such as airway obstruction, bronchopneumonia, more sputum secretion and sticky blockage of the airway. It is also possible to drain the child in a postural position, so that the site of atelectasis is on the uppermost side to facilitate the discharge of sputum. In cases of pulmonary atelectasis where the sputum is too thick to be easily coughed up or where conventional medical treatment is ineffective, bronchoscopic treatment can be used to directly aspirate the secretions blocking the airway through the bronchoscope. For other causes of atelectasis, such as atelectasis caused by sarcoid or tumor occlusion, interventional treatment is required to clear the airway. In addition, for atelectasis caused by pleural effusion or a large amount of pneumothorax, thoracentesis, drainage or even closed chest drainage should be performed to relieve the atelectasis.