A chest tube (chest drain, thoracic catheter, tube thoracostomy, or intercostal drain) is a flexible plastic tube that is inserted through the chest wall and into the pleural space or mediastinum. It is used to remove air (pneumothorax[2]) or fluid (pleural effusion, blood, chyle), or pus (empyema) from the intrathoracic space. It is also known as a bülau drain or an intercostal catheter.