Pneumothorax

Description

A pneumothorax is simply a collection of air (pneumo) within the chest (thorax). The lungs are contained within the chest wall but are not attached to the ribs. The ribs and the lungs have their own separate linings and are allowed to move against each other as you breathe. There is normally a very small amount of fluid (see pleural ebiopsy article) between the two layers to lubricate this movement, but no air.  There is, however, always air contained within the lungs as you breathe (even when you breathe out completely). There should never be air “outside/around the lung”. If air leaks into the space between the ribs and the lungs, the lung will collapse either partially or completely as a result of changes in pressure within the chest and may result in pain and shortness of breath, caused by a ‘pneumothorax’.

What causes a pneumothorax?

Air can either enter the pleural space from outside (through the chest wall) or leak out from the lung itself.

A ‘primary’ pneumothorax occurs in generally healthy young people where a small ‘bleb’ (similar to a single ‘bubble-wrap’ bubble) bursts and air leaks out. There may be a family tendency and it often occurs in very tall and thin individuals.

A ‘secondary pneumothorax’ occurs for example when there is underlying lung disease such as emphysema, previous tuberculosis or cystic fibrosis.

A traumatic pneumothorax results from either a sharp or a blunt trauma. A bullet or knife wound may allow air to enter from the outside, but if the underlying lung is also damaged, air may continue to leak out from the lung. Broken ribs may also cut into the lung tissue, allowing air to leak out. Individuals undergoing lung-related procedures such as biopsies or bronchoscopy are also at risk of a pneumothorax.

What are the symptoms and how is it diagnosed?

The most frequent symptom is shortness of breath – this may occur abruptly in the case where a large amount of air accumulates quickly or slowly over a few hours or days, where a slow leak exists. Sharp stabbing-type chest pains may also occur. If a very large amount of air accumulates quickly, this might cause pressure on the heart, resulting in a life-threatening drop in blood pressure with respiratory failure.

A pneumothorax can be diagnosed both clinically and with special tests. In small pneumothoraces there may be no clinical signs but as the amount of air increases, reduced breathing sounds can be noted and the lung sounds ‘more hollow’ when “tapped/percussed”. In severe cases the trachea/wind pipe can be pushed to one side – this is a sign that urgent treatment is generally required. Air may also leak out of the chest into the muscle/fat tissue itself and results in “crepitus”, which feels like bubble wrap under the skin. 

A chest X-ray (taken in the standing position) is a very simple way of diagnosing a pneumothorax, as the escaped air is visible between the lung tissue and the chest wall. In a lying position (such as in the intensive care unit) it is more difficult to see on a chest X-ray. A CT scan can also easily detect a pneumothorax, but is generally not required for routine diagnosis.

How is it treated?

There are various guidelines governing how a pneumothorax is best treated. The treatment will however vary, depending on the individual who has the pneumothorax, the attending doctor and the facilities available.

Generally, a small pneumothorax with little shortness of breath does not require any urgent treatment. Moderate size and traumatic pneumothoraces will require a drain to allow the air to escape. Various modern drainage systems are now available with a thin tube and valve system. If there is fluid (blood) in the pleural space or the pneumothorax came about as a result of trauma, a thick tube (size of your ring finger) is usually required and is inserted through the chest wall. (Local anaesthetic is always given to reduce the pain.) A one-way valve is attached to the tube, which allows the air and fluid to drain out, without anything going back in.

If the doctor suspects that the lung is severely compressed (tension pneumothorax), a needle is inserted through the chest wall to allow the air to escape before a formal drain is inserted.

The length of time it takes for all the air to be drained out varies depending on the underlying cause. In small spontaneous pneumothoraces, the air may be sucked out using a needle and syringe and no further treatment required. If major trauma or tuberculosis is the underlying reasons, it may take weeks to months to heal.

What are the long-term outcomes?

The long-term outlook is generally good, but again depends on the underlying cause. In high risk individuals (tall and thin with a family history of previous pneumothoraces) there may be multiple blebs on the lung surface. It may be advisable to prevent any further pneumothoraces by “sticking the lung and chest wall together” by a procedure called a pleurodesis. Several techniques exist but simply the lining of the lung is irritated either chemically or physically and allowed to stick to the chest wall. This does not affect breathing, but obliterates the potential space between the lung and chest wall, thus preventing any further air leaks.

Each case will be assessed individually for future risks of a recurrence and weighed up against the need and risks of a preventative procedure.

Can I fly or dive after a pneumothorax?

Flying and diving are prohibited with a pneumothorax due to the changes in air pressure.  Provided your doctor has confirmed that it has resolved, one can generally fly one to two weeks after a pneumothorax. The chance of a recurrence occurring when flying is thought to be low. If you are worried about a second pneumothorax happening, consult a lung specialist to advise you on the risk and preventative options.

Revised by Richard van Zyl-Smit, MBCHB, MRCP(UK), DIP HIV Man (SA), FCP(SA) Cert Pulm (SA), Specialist Physician and Pulmonologist, Division of Pulmonology and UCT Lung Institute, Department of Medicine, University of Cape Town, (October 2010)