Thoracostomy is a medical procedure that involves creating an opening in the chest wall to allow air or fluid to escape from the pleural space, which is the area between the lungs and the chest wall. This procedure is often performed to treat conditions such as pneumothorax (collapsed lung) or pleural effusion (fluid buildup). During a thoracostomy, a tube is inserted through the chest wall into the pleural space. This tube, known as a chest tube, helps to re-expand the lung and restore normal breathing. The procedure can be done in emergency situations or as part of planned treatment for certain lung conditions.