A pneumothorax is a condition in which air becomes trapped in the pleural space. This is usually caused by trauma to the lung, or a “punctured” lung. The patient continues to breathe, pulling air into the injured lungs, but the air escapes into the chest cavity. It cannot follow the path back up and out of the mouth as intended. As this air begins to accumulate, it causes pressure to build up inside the thorax. When pressure begins to affect other nearby organs, this is known as a tension pneumothorax. It is quite possible to have a punctured or collapsed lung without having a buildup of pressure- this is simply called a pneumothorax.
The tension caused by this building pressure causes several problems. First, the lungs cannot properly exchange air and this can result in hypoxia. Second, the pressure can compress the other organs of the chest, such as the heart. This can lead to decreased cardiac output. The way to treat this condition is to find a way to vent the chest cavity. This will allow the organs to return to their normal positions and relieve the pressure. However, for the lung to reinflate, the lung will have to recover from the injury. Usually, this is accomplished by inserting a chest tube.
Not all pneumothoraces are tension pneumothoraces resulting from injury, but you should be on guard for tension to increase even in patients with a simple pneumothorax. A pneumothorax can occur spontaneously. Spontaneous pneumothoraces tend to occur in tall, thin smokers, and can cause significant problems with breathing. In some cases, the elderly may be at risk for pneumothoraces, but these tend to be related to underlying lung disease.
The most common cause of tension pneumothorax is penetrating trauma. Whether from a stabbing injury or a gunshot, the injury to the pleural tissue can cause the lung to collapse. In addition, you should be aware that those who have had chest surgery are also at risk for tension pneumothorax, which may result in cardiac arrest. For this reason, it is important to know the signs of tension pneumothorax and be prepared to decompress the chest if necessary.
The symptoms of pneumothorax can range from mild to severe. However, when it is a tension pneumothorax, the symptoms are most often quite severe. For spontaneous pneumothoraces, there may be no symptoms at all, but shortness of breath and chest pain may occur, and blebs in the pleural spaces can show up on chest x-rays. Patients with these symptoms should be watched carefully in case they develop a tension pneumothorax.
In tension pneumothorax, the clinician will see the organs of the chest and mediastinum shift away from the side where the problem has occurred. This means that the trachea, heart and other structures will deviate away from the midline. As many tension pneumothoraces start with a penetrating wound, you will need to assess the patient for invasive wounds, such as a stab or gunshot wound. In some cases, the opening will be very small and may be easily missed. Surgery is also considered invasive, so a patient with a history of lung or chest surgery is also a candidate for possible tension pneumothorax. Signs of this condition are hypotension, hypoxia, dyspnea, and chest pain.
The treatment of tension pneumothorax revolves around releasing the air that has gathered in the pleural space. Other forms of pneumothorax may be treated differently, but a trauma-induced tension pneumothorax or hemothorax almost always requires insertion of a chest tube. In the field, a large-bore needle may be inserted into the second intercostal space at the midclavicular line. A one-way valve should be placed on the end of this catheter to allow the pressures inside the chest to regulate itself. Unfortunately, research studies have shown that emergency personnel often have a difficult time finding the correct landmarks for this procedure and may end up causing additional trauma. A way to alleviate this problem with landmarks on the anterior chest is to go laterally. The new way of decompressing a chest was started during the war in the middle east when the Kevlar vests our soldiers wore inhibited a medic from decompressing the anterior aspect of a chest. It was determined that you could just as easily (or sometimes more easily) decompress the 4th intercostal space mid-axillary line. This could be accomplished without having to remove a protective vest
In the hospital, chest tubes are inserted into the pleural space and hooked up to a water seal that allows for decompression of the chest. Depending on the nature of the pneumothorax, several chest tubes may be needed to evacuate the air or the blood that is taking up space in the pleural cavity. If bleeding is the problem, immediate surgical intervention is needed to stop the bleeding and stabilize the patient. Usually, inserting one chest tube in the case of tension pneumothorax in the hospital is enough to decompress the chest, take the pressure off thoracic structures, and allow the patient to recover.