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  • AutorenbildMichael Mutter

Asthma and diving

After the last spell of winter, nothing stands in the way of the pollen season. Many divers are affected, because according to the Lung League, one in 14 people in Switzerland suffers from asthma. What to bear in mind when diving with asthma:

Image template: Karin Aggeler


Asthma is characterized by the acute occurrence of inflammation of the bronchi. As a result, they contract and their mucous membranes swell. This leads to a narrowing of the airways. Characteristics of an asthma attack can be:

  • Sudden shortness of breath

  • A whistling exhalation sound

  • A tight feeling over the chest

  • A feeling of suffocation

  • Rapid and superficial breathing

  • Dry cough or cough with thick sputum

In extreme cases, a lack of oxygen can lead to cyanosis (bluish lips) and cold sweats due to shock.

Asthma is triggered by various stimuli. Medically, a distinction is made between intrinsic and extrinsic asthma.

Extrinsic asthma

This is the best-known form of asthma, which is triggered by allergens such as pollen, house dust (mites), animal fur or occupational substances such as flour dust etc.

Intrinsic asthma

This form includes exercise-induced asthma, cold-induced asthma or asthma caused by infections.

Most asthmatics have a mixed form. They react to allergens, but can also react with an asthma attack in other situations, such as during an infection or when breathing in cold air.


The diagnosis can usually be deduced from the typical symptoms. It is confirmed by lung function tests (spirometry) and allergy tests. If the diagnosis remains uncertain, the bronchi can be specifically provoked by inhaling irritants (bronchoprovocation) in order to measure how much they constrict.

First pillar of prevention: avoid triggers

Prevention and therapy

Asthma cannot be cured, but it can be treated well. The prevention of attacks is based on allergen avoidance (avoiding the triggers), such as sanitizing the bedroom against house dust mites, banning the house cat in the case of cat hair allergy or even a change of profession if allergen avoidance is not possible at the workplace, such as in the case of bakers.

Inhalation therapy is the basic treatment.

Treatment primarily involves inhalation therapy to dilate the bronchial tubes and reduce inflammation, whereby preparations containing corticosteroids, which only act on the bronchial tubes, are also used. Asthmatics should always carry their inhaler with them for emergency treatment of an attack.

Hay fever and asthma are siblings on different floors.

The little brother of asthma, hay fever, is found one level higher in the area of the nose and sinuses, where the swollen mucous membranes manifest themselves in the well-known symptoms. Hay fever is also primarily treated with nasal sprays, but "allergy inhibitors", so-called antihistamines, can also be used in tablet form.

Figure: Pathophysiology of asthma during diving

When breathing in, the airways expand and air enters the alveoli easily despite swelling of the bronchial mucosa (red). When exhaling, the lung volume decreases and the airways become narrower. In asthma, this means that the inhaled air cannot or can only be partially exhaled. It remains trapped in the alveoli (air trapping). The alveoli become over-inflated. When ascending at the end of a dive, according to the Boyle-Mariotte law, the alveoli are further inflated in proportion to the drop in ambient pressure when the air cannot escape. This can result in pneumothorax.


Consequences for diving

The main problem with asthma is barotrauma. Diving with constricted bronchial tubes can lead to insufficient pressure equalization in the alveoli, which are overstretched when surfacing. This can result in pulmonary barotrauma and even pneumothorax.

An asthma attack can lead to lung barotrauma and even pneumothorax.

Hay fever can cause barotrauma in the paranasal sinuses due to the swelling of the mucous membrane and, if the Eustachian tube malfunctions, also in the middle ear.

Diving is permitted with asthma - as long as it is well controlled.

If asthma is well controlled, i.e. if there are no symptoms, diving is permitted without restriction. The prerequisite for this is that inhalation therapy is used regularly, not just immediately before a dive, but in general. The same applies to hay fever. Self-measurements of lung function with the peak flow meter to determine the maximum exhalation flow or regular medical follow-up with lung function tests serve to monitor therapy.

The dry, cold breathing gas is poison for asthmatics.

Unfortunately, diving itself is a provoking factor for an asthma attack. The breathing gas is poison for asthmatics because it is cold and dry. For this reason, asthmatics should use inhalation therapy generously before diving. If asthmatics experience even mild symptoms such as coughing and discomfort underwater, the dive must be aborted.

Asthmatics should have their inhaler ready at hand at all times.

For this reason, divers affected by asthma should always have their inhaler to hand, even on a dive boat. Ideally, dive buddies know the diagnosis and how to act in the event of an attack. This is treated with inhalation, repetitively in an emergency. In the worst case, the emergency services should be called and oxygen administered.

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