<P> The trachea is the tube that carries air from the throat to the lungs . It is also commonly referred to as the windpipe . The trachea is one of the most important parts of the respiratory system and damage to the trachea can indicate a life - threatening emergency . The normal position of the trachea is straight up and down, running along the center of the front side of the throat . Certain conditions can cause the trachea to shift to one side or the other . This is a medical emergency that requires immediate medical attention to discover the cause of the shift and begin an appropriate course of treatment . There are several causes for a tracheal deviation, and the condition often presents along with difficulty breathing, coughing and abnormal breath sounds . The most common cause of tracheal deviation is a pneumothorax, which is a collection of air inside the chest, between the chest cavity and the lung . A pneumothorax can be spontaneous, caused by existing lung disease, or by trauma . Treatment varies, depending on the severity of the pneumothorax . Smaller pockets of air tend to dissipate on their own, while larger areas can cause complications and are usually vented by a needle in the chest . As soon as the pneumothorax is treated, the tracheal deviation also will resolve itself . A congenital lack of one lung, surgical removal of a lung or pleural fibrosis, which is an inflammation of the lung membranes caused by an infection . As a result of the wide range of causes of tracheal deviation, it is absolutely essential to seek medical attention in order to obtain an accurate diagnosis . </P> <P> Since tracheal deviation is a sign as opposed to a condition, treatment is focused on correcting the cause of the finding . In the case of pneumothorax, thoracentesis or chest tube insertion is performed to relieve the pressure within the affected pleural cavity . </P>

Which of the following may cause the trachea to shift to the right