What are the causes and treatment for atelectasis of lungs?

Open lungs up: Atelectasis of lung means there is no air iin a portion of lung. This occurs if a branch of the bronchi leading to that part of the lung is blocked by mucous/phlegm or even a foreign body (like an aspirated piece of food for example). Often use of cough, bronchodilators can open bronchi up and clear phlegm or a bronchoscope can be used to suction it out.