Understanding asthma and diving

Understanding asthma and diving

What is asthma?

Asthma is a long-term illness that can be controlled with proper treatment. Unfortunately, it cannot be cured. It affects up to 1 in 5 children and 1 in 10 adults. It is the cause of many lost school days and many lost days of work.

People with asthma have episodes of shortness of breath that can be caused or worsened by certain trigger factors. Shortness of breath is due to a narrowing of the small airways in the lungs as a result of inflammation and muscle spasms.

How do the lungs work?

Each breath draws air into the trachea, or trachea. The trachea divides into two more tubes called bronchi, which then divide into smaller and smaller airways called bronchioles, and finally lead to small air sacs called alveoli. Here in the alveoli, oxygen from the air enters the bloodstream. At the same time, carbon dioxide produced in the body's tissues moves from the blood into the air sacs and then out of the body.

What happens during an asthma attack?

Asthma occurs due to narrowing and inflammation of the small airways. In asthma, there is a special type of inflammation that narrows the small airways, making them “twitchy” and very sensitive to environmental changes. The airways also become blocked by sticky mucus, and this blockage can occur very quickly.

During an asthma attack, breathing becomes more difficult, even at rest. There may be coughing or wheezing, which is a musical sound when breathing. Asthma can also occur at night while you sleep. Asthma can vary in severity from mild chest tightness with coughing and wheezing on exertion to a life-threatening attack of severe shortness of breath requiring urgent medical attention.

What is diving?

Scuba means Self Contained Underwater Breathing Apparatus. Developed by Jacques Costeau, scuba diving has opened up a whole new world of underwater exploration without the heavy diving equipment of air tubes on the surface. Over the last 20 years, the use of diving equipment for recreational purposes has increased tremendously.

What are the dangers of diving?

Many sporting activities involve risks and diving is no exception. The chances of dying while diving are slightly higher than those of boxing and over 40 times higher than those of playing soccer or water skiing.

Many of the dangers have to do with pressure. A diver breathes air into his lungs at a pressure equal to the depth of the water in which he is swimming. Pressure increases rapidly underwater and at 30 feet depth the pressure is twice as high as at the surface.

When the diver breathes into his lungs from a scuba tank at 30 feet and then comes to the surface, the air in the chest expands as the air pressure drops. The expanding air must escape, usually through the mouth or nose, and bubbles to the surface. When one of the airways becomes blocked (which can happen with asthma), air cannot escape and expands in the lung, eventually causing the lung to burst. The consequences can be life-threatening. Air can escape from the ruptured lung into the chest cavity (a condition called pneumothorax), which can cause difficulty breathing, chest pain, and sometimes death, or escape into blood vessels and carry bubbles to the heart and brain (a condition known as air embolism). is often fatal. These two events are called barotrauma.

Why is diving so dangerous for asthmatics?

Scuba diving poses a particular risk for people with asthma. Some of the typical asthma trigger factors are present during scuba diving. Using any other underwater breathing system also carries the same risks.

Breathing in cool, dry air is very irritating to asthmatic airways. Diving gas is dry and, when released through a small valve, produces a cooling effect. So a diver breathes in a cold and dry mixture of air, which is potentially very dangerous for people with asthma. Heavy physical exertion, such as swimming against a current with a heavy tank on your back, can cause shortness of breath and even asthma. Accidental inhalation of salt or fresh water can cause coughing, and a fine mist of seawater can cause airway constriction by directly irritating the airways.

The general stress and anxiety of diving can compound the situation and set the stage for a very serious asthma attack. Imagine the scene for a person with asthma who develops an asthma attack underwater. Of course, using a relief buffer is out of the question. When the diver attempts to return to the surface, some areas of the lungs may be blocked due to the obstruction of the asthmatic airways, leaving the expanding air in these areas with nowhere to escape. The person with asthma is therefore at much greater risk of barotrauma.

Does this mean a person with asthma can never scuba dive?

People with asthma are at risk of developing asthma at any time, but even more so when trigger factors are likely to be present, such as in diving. Many people with asthma are unaware of the high risks that diving poses to them. Although the majority of people with asthma will experience asthma at least some of the time during their lives, some actually seem to outgrow it; and for them, diving may be no more risky than for the general population. Most diving medical experts agree that if a person has had no symptoms or signs of asthma for at least five years and has required absolutely no anti-asthma medication for that period and has a normal medical examination including breathing tests, they should be allowed to dive after being informed of the risks.

Can adults with childhood asthma be sure that asthma won't come back while diving?

Although one can never be 100% sure that asthma will not recur, it is possible to undergo a challenge test with hypertonic saline. This test, which can be performed in most specialized pulmonary function laboratories, involves inhaling a mist of salt water from an ultrasonic nebulizer, with breath tests to determine whether bronchial narrowing is occurring. If this is the case, the person is still vulnerable to an acute asthma attack while underwater and should not dive. A negative test provides additional reassurance that the person is unlikely to develop asthma while diving.

Is snorkel diving also dangerous for people with asthma?

Snorkel diving is much less risky than scuba diving for people with asthma. The main reason for the difference is that snorkelers do not breathe air at depth and therefore the risk of lung bursting during ascent is much lower. However, common sense dictates that asthma should be stable and under control before snorkeling, as accidental suction of water and physical exertion associated with swimming against a current can also lead to an asthma attack. Some of the best underwater videos and films have been made by divers with snorkels, goggles and handheld cameras.

Inspired by Aileen Norgell, MD