The injuries may necessitate a procedure, with the most common being the insertion of an intercostal drain, more commonly referred to as a chest tube. This tube is typically placed because it helps restore a certain balance in pressures (usually due to misplaced air or surrounding blood) that are impeding the lungs ability to inflate and thus exchange vital gases that allow the body to function. A less common procedure that may be employed is a pericardiocentesis which by removing blood surrounding the heart, permits the heart to regain some ability to appropriately pump blood. In certain dire circumstances an emergent thoracotomy may be employed.