Pneumothorax

Pneumothorax is a collection of air or gas in the chest or pleural space thatcauses part or all of a lung to collapse. Normally, the pressure in the lungs is greater than the pressure in the pleural space surrounding the lungs. However, if air enters the pleural space, the pressure in the pleura then becomes greater than the pressure in the lungs, causing the lung to collapse partially or completely. Pneumothorax can be either spontaneous or due to trauma.

If a pneumothorax occurs suddenly or for no known reason, it is called a spontaneous pneumothorax. This condition most often strikes tall, thin men between the ages of 20 to 40. In addition, people with lung disorders, such as emphysema, cystic fibrosis, and tuberculosis, are at higher risk for spontaneouspneumothorax. Traumatic pneumothorax is the result of accident or injury dueto medical procedures performed to the chest cavity, such as thoracentesis ormechanical ventilation. Tension pneumothorax is a serious and potentially life-threatening condition that may be caused by traumatic injury, chronic lungdisease, or as a complication of a medical procedure. In this type of pneumothorax, air enters the chest cavity, but cannot escape. This greatly increased pressure in the pleural space causes the lung to collapse completely, compresses the heart, and pushes the heart and associated blood vessels toward theunaffected side.

The symptoms of pneumothrax depend on how much air enters the chest, how muchthe lung collapses, and the extent of lung disease. Symptoms include the following, according to the cause of the pneumothorax:

• Spontaneous pneumothorax. Simple spontaneous pneumothorax is caused by a rupture of a small airsac or fluid-filled sac in the lung. It may be related to activity in otherwise healthy people or may occur during scuba diving or flying at high altitudes. Complicated spontaneous pneumothorax, also generally caused by rupture ofa small sac in the lung, occurs in people with lung diseases. The symptoms of complicated spontaneous pneumothorax tend to be worse than those of simplepneumothorax, due to the underlying lung disease. Spontaneous pneumothorax ischaracterized by dull, sharp, or stabbing chest pain that begins suddenly and becomes worse with deep breathing or coughing. Other symptoms are shortnessof breath, rapid breathing, abnormal breathing movement (that is, little chest wall movement when breathing), and cough.
• Tension pneumothorax. Following trauma, air may enter the chest cavity. A penetrating chest wound allows outside air to enter the chest, causing the lung to collapse. Certain medical procedures performed in the chest cavity, such as thoracentesis, also may cause a lung to collapse. Tension pneumothorax may be the immediate resultof an injury; the delayed complication of a hidden injury, such as a fractured rib, that punctures the lung; or the result of lung damage from asthma, chronic bronchitis, or emphysema. Symptoms of tension pneumothorax tend to be severe with sudden onset. There is marked anxiety, distended neck veins, weak pulse, decreased breath sounds on the affected side, and a shift of the mediastinum to the opposite side.

To diagnose pneumothorax, it is necessary for the healthcare provider to listen to the chest (auscultation) during a physical examination. By using a stethoscope, the physician may note that one part of the chest does not transmitthe normal sounds of breathing. A chest x ray will show the air pocket and the collapsed lung. An electrocardiogram (ECG) will be performed to record theelectrical impulses that control the heart's activity. Blood samples may be taken to check for the level of arterial blood gases.

A small pneumothorax may resolve on its own, but most require medical treatment. The object of treatment is to remove air from the chest and allow the lung to re-expand. This is done by inserting a needle and syringe (if the pneumothorax is small) or chest tube through the chest wall. This allows the air toescape without allowing any air back in. The lung will then re-expand itselfwithin a few days. Surgery may be needed for repeat occurrences.

Most people recover fully from spontaneous pneumothorax. Up to half of patients with spontaneous pneumothorax experience recurrence. Recovery from a collapsed lung generally takes one to two weeks. Tension pneumothorax can cause death rapidly due to inadequate heart output or insufficient blood oxygen (hypoxemia), and must be treated as a medical emergency.

Preventive measures for a non-injury related pneumothorax include stopping smoking and seeking medical attention for respiratory problems. If the pneumothorax occurs in both lungs or more than once in the same lung, surgery may beneeded to prevent it from occurring again.