In medicine (pulmonology), a pneumothorax or collapsed lung is a medical emergency that can result from a penetrating chest wound or barotrauma to the lungs. Additionally, it can develop spontaneously in predisposed individuals.
Signs and symptoms
Sudden shortness of breath and cyanosis (turning blue) are the main symptoms. In penetrating chest wounds, the sound of air flowing through the punction hole may indicate pneumothorax. The flopping sound of the punctured lung is occasionally heard.
If untreated, the hypoxia will lead to loss of consciousness and coma. In addition, shifting of the mediastinum towards the site of the injury can obstruct the aorta and other large blood vessels, depriving distal tissues of blood. Untreated, a severe pneumothorax can lead to death within several minutes.
Spontaneous pneumothoraces are reported in young people with a tall stature. As men are generally taller than women, there is a preponderance among males. The reason for this association, while unknown, is supposed to be the presence of subtle abnormalities in connective tissue.
Pneumothorax can also occur as part of medical procedures, such as the insertion of a central line (an intravenous catheter) in the subclavian vein . While rare, it is considered a serious complication and needs immediate treatment. Other causes include mechanical ventilation, emphysema and rarely other lung diseases (pneumonia).
The absence of audible breath sounds through a stethoscope indicates that the lung is not unfolded in the pleural cavity. If the symptoms are doubtful, an X-ray of the chest can be performed, but in severe hypoxia, emergency treatment has to be administered first.
The lungs are located inside the chest cavity, which is a hollow space. Air is drawn into the lungs by the diaphragm (a powerful abdominal muscle). The pleural cavity is the region between the chest wall and the lungs. If air enters the pleural cavity, either from the outside or from the lung, the lung collapses and it becomes mechanically impossible for the injured person to breathe, even with a patent airway.
If a piece of tissue forms a one-way valve that allows air to enter the pleural cavity from the lung but not to escape, overpressure can build up with every breath; this is known as tension pneumothorax. It may lead to severe shortness of breath as well as circulatory collapse, both life-threatening conditions.
Small pneumothoraces often resolve spontaneously and may require no other treatment than clinical observation. A large pneumothorax or tension pneumothorax is a medical emergency and may require surgery.
Penetrating wounds require immediate coverage with pressure bandages made air-tight with petroleum jelly or clean plastic sheeting. The sterile inside of plastic bandage packaging is good for this purpose; however any airtight material, even the cellophane of a cigarette pack, can be used. A small opening needs to be left open, so the air can escape while the lung reinflates.
Any patient with a penetrating chest wound must be closely watched at all times and may develop a tension pneumothorax or other immediately life-threatening respiratory emergency at any moment. They cannot be left alone.
Blast injury or spontaneous
If the air in the pleural cavity is due to a tear in the lung tissue (in the case of a blast injury or tension pneumothorax), it needs to be released. A thin needle can be used for this purpose, to relieve the pressure and allow the lung to reinflate.
Emergency services can generally provide oxygen therapy and positive pressure ventilating during transport to a hospital. Intubation may be required, even of a conscious patient, if the situation deteriorates. Advanced medical care and immediate evacuation are strongly indicated.
In case of mountain evacuation (MEDEVAC), altitude can affect the patient. If the patient becomes short of breath while being transported, returning to the former height is important. Even a helicopter might have to alter its altitude multiple times before it can land, and reach an ambulance.
In case of penetrating wounds, these require attention, but generally only after the airway has been secured and a chest drain inserted. The drain is connected to a vacuum, and allows the lung to unfold inside the pleural cavity. Supportive therapy may include mechanical ventilation.
The pneumothorax is followed up with repeated X-rays. If the air pocket has become small enough, the vacuum drain can be clamped temporarily or removed.
Recurrent pneumothorax may require pleurodesis. This is the injection of a (basically toxic) substance that triggers an inflammatory reaction, leading to adhesion of the lung to the parietal pleura. Substances used for pleurodesis are talc and bleomycin.
Last updated: 02-07-2005 01:13:25
Last updated: 05-03-2005 17:50:55