There are three obvious reasons for not diving:

Disorders that may lead to altered consciousness
Disorders that inhibit the “natural evolution of Boyle’s Law”.
Disorders that may lead to erratic and irresponsible behavior.

Pneumothorax

Any lung disease, procedure, or event that can result in air trapping is thought to be a contraindication to diving. That having been said, most diving medical people would say that spontaneous, traumatic and post-surgical pneumothoraces are felt to be disqualifying, due to the almost certain presence of ‘air trapping’, either from the underlying disease process or the surgical procedure. Once a person has a spontaneous pneumothorax, recurrences are likely.

Traumatic and iatrogenic pneumothoraces vary in degree, those due to blunt or penetrating trauma usually leave lacerations of the lung surface, often with significant radiographic changes that indicate scarring and air trapping. Such individuals should not be allowed to dive. In the event of isolated injury without significant scarring or air trapping, such as is seen with ice pick trauma, clean knife penetration, subclavian line placement, thoracentesis needle injury and some some mediastinal surgery, diving should be permitted, pending proper radiological evaluation to rule out air trapping.

There are really two dangers involved -arterial gas embolism, with the possibility of immediate death due to coronary or vertebrobasilar embolism, and tension pneumothorax–which severely complicates recompression treatment of AGE [arterial gas embolism]. A large pneumothorax requires the insertion of a needle for relief and a tube management if treated in the chamber.

There appears to be little evidence that the dangers of spontaneous pneumothorax present a threat over a lifetime; there have not been any fatalities reported attributed to an AGE due to a previous spontaneous pneumothorax or previous thoracic surgery [NOAA Statistics, 1972-1982].

Spontaneous pneumothorax is an inherited disease which leaves some people with weakened areas of the pleural lining of the lung, called blebs or blisters.These can occasionally burst and cause air to leak from the lung to the chest cavity, resulting in a pneumothorax (‘air in the chest’). It is ‘spontaneous’ in the sense that there was no trauma or surgical cause of the ruptured bleb. It can occur when the individual is exercising, straining, or performing some other physical task, but most of the time it just happens. If one spontaneous pneumothorax has occurred, there is a 33% chance that another will occur within 2-3 years 30% will have a recurrence after 3 years, and there is a 60% long term risk for another pneumothorax.

When a lung collapses while diving, the air in the chest cavity is at the ambient pressure of the dive depth. Upon ascending, the air in the chest cavity expands, and further compresses the lung (tension pneumothorax). This is a life-threatening situation and is one of the main reasons that a history of spontaneous pneumothorax is an absolute contra-indication to diving since most divers and dive boats are not prepared to provide first aid to a diver with pneumothorax. One of the symptoms of a small
pneumothorax is a voice change after a dive. This would raise a warning flag about further diving as there might be a small pneumothorax which in itself is not harmful, but which will cause a serious problem if the diver does another dive.

Gas embolism, with air getting into the arterial circulation, is another thing that can happen, often with brain and cardiac symptoms.

Surgical procedures called pleurodesis (scarring the lung surface) and pleurectomy (excision of the pleura, a thin covering of the lungs) are commonly performed for recurrent collapsed lungs. There is a recurrence rate of 8 percent following pleurodesis. Recurrence is rare following pleurectomy. Even if recurrence of collapsed lung does not occur, the underlying cystic lung disease of the other lung remains, with the inherent danger now being pulmonary barotrauma with air embolism. The following are absolute contraindications to diving:

—Diving within three months after any type of collapsed lung.
—Spontaneous collapsed lung in beginners.
—Expert divers with recurrent collapsed lung after pleurectomy.

If you feel that you will continue to dive regardless of the risk, Spiral CT scans of your lungs should be performed so as to detail the degree of risk involved. Best advice here would be not to dive until you have been cleared by your chest specialist.

(Developed from material provided by Maurizio Schiavon, MD, Consultant to Diving Medicine Online)