Treatment of TBI varies based on the location and severity of injury and whether the patient is stable or having trouble breathing,[2] but ensuring that the airway is patent so that the patient can breathe is always of paramount importance.[14] Ensuring an open airway and adequate ventilation may be difficult in people with TBI.[3] Intubation, one method to secure the airway, may be used to bypass a disruption in the airway in order to send air to the lungs.[3] If necessary, a tube can be placed into the uninjured bronchus, and a single lung can be ventilated.[3] If there is a penetrating injury to the neck through which air is escaping, the trachea may be intubated through the wound.[14] Multiple unsuccessful attempts at conventional (direct) laryngoscopy may threaten the airway, so alternative techniques to visualize the airway, such as fiberoptic or video laryngoscopy, may be employed to facilitate tracheal intubation.[14] If the upper trachea is injured, an incision can be made in the trachea (tracheotomy) or the cricothyroid membrane (cricothyrotomy, or cricothyroidotomy) in order to ensure an open airway.[6] However, cricothyrotomy may not be useful if the trachea is lacerated below the site of the artificial airway.[14] Tracheotomy is used sparingly because it can cause complications such as infections and narrowing of the trachea and larynx.[26] When it is impossible to establish a sufficient airway, or when complicated surgery must be performed, cardiopulmonary bypass may be used—blood is pumped out of the body, oxygenated by a machine, and pumped back in.[26] If a pneumothorax occurs, a chest tube may be inserted into the pleural cavity to remove the air.[19]