What is asthma?
Asthma is a respiratory disease which is usually characterised by chronic airway inflammation. Inflamed airways swell, tighten, and produce excess mucus, causing difficulties for the air to flow into and out of the lungs. People with asthma struggle to breathe. When asthma symptoms suddenly worsen, the result is an asthma attack. During an asthma attack, the airways are swollen and mucus is thicker than usual.
Airway inflammation and airway hyper-responsiveness usually define asthma sign and symptoms, but they are not necessarily sufficient to make an asthma diagnosis. The diagnosis of asthma should also be based on the history of respiratory symptoms, including wheezing, shortness of breath, chest tightness, cough and variable airflow limitation. These symptoms are common for both asthma in children and asthma in adults.
Some symptoms of asthma are typical for respiratory diseases. The probability of being diagnosed with asthma is increased if the following characteristics are also present with the symptoms:
- more than one symptom (wheeze, shortness of breath, cough, chest tightness, and airflow limitation), especially for asthma in adults
- the symptoms often worsen at night or in the early morning
- the symptoms vary over time and in severity
- the symptoms are triggered by viral infections (such as a common cold), an exercise, allergen exposure, changes in weather, or irritants such as car exhaust fumes, smoke, and strong odours
Asthma symptoms can be caused to appear by several factors to which the inflamed airways are sensitive. These are known as asthma triggers. The most common asthma triggers are:
- Allergens, such as dust mites, cockroach, pollens, moulds, pet fur, and rodents
- Irritants in the air, such as tobacco smoke, smog, fumes, dust, and the burning of wood and charcoal
- Underlying respiratory conditions, such as common cold, flu, chronic obstructive pulmonary disease (COPD), asthma-COPD overlap syndrome (ACOS), gastroesophageal reflux disease (GERD) and sinus problems
- Changes in weather
- Expression of strong emotion, such as a laughter, stress and crying
- Medicines that the asthma patient is sensitive to, such as aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), and medicines that worsen asthma symptoms like beta blockers
- Other asthma triggers, such as sulphites in food and hormonal changes during the menstrual cycle
Causes and risk factors
While the cause of asthma is unclear, asthma can develop accordingly to host factors and environmental factors. Host factors predispose individuals to, or protect them from, developing asthma. These host factors include:
- Atopy (family history of allergies)
- Airway hyper-responsiveness
- Low or high birth weight
- Maternal and parental smoking
- High salt intake and diet in general
- Pet ownership
- Breast milk
- Hygiene hypothesis
Environmental factors influence susceptibility to development of asthma in predisposed individuals, precipitate asthma exacerbation, and/or cause asthma symptoms to persist. These environmental factors include:
- Indoor allergens (such as dust mites and animal fur)
- Cockroach allergen and fungi (such as moulds and yeasts)
- Outdoor allergens (such as pollens, moulds, yeasts)
- Occupational sensitizers
- Tobacco smoke
- Air pollution
- Respiratory infections (such as atypical pneumonia and viral infections)
Asthma treatment is directed at controlling the symptoms rather than curing the condition. Asthma can be treated with long-term control medicines and quick-relief medicines.
Long-term control medicines help reduce inflammation in the airways and prevent asthma symptoms. These long-term asthma controllers include:
- Inhaled corticosteroids prevent and reduce airway swelling, as well as reduce mucus in the lungs. These long-term control medicines treat asthma most effectively.
- A combination of inhaled corticosteroid and a long-acting beta agonist relax the smooth muscles to open the airway. These medicines should not be taken separately.
- Omalizumab (anti-IgE) prevents asthma symptoms from begin triggered by an allergy, by blocking the antibody that causes allergies. Anti-IgE is given as a shot every 2 or 4 weeks and it is given only if asthma medicines do not effectively work to control asthma symptoms.
- Leukotriene modifiers reduce swelling inside the airways and relaxes the smooth muscles. These medicines come in pill or liquid form.
- Cromolyn sodium, which is an inhaled non-steroid medicine, prevents swelling in the airways, caused by an asthma trigger.
- Theophylline opens the airways by relaxing the smooth muscles. Theophylline comes as a tablet, capsule, solution and syrups.
- Oral corticosteroids, taken in pill or liquid form, are used as long-term therapy to treat severe asthma when asthma attacks do not respond to asthma medicines.
Quick-relief medicines or the so-called rescue medicines can be used to quickly ease asthma symptoms that may flare up. These asthma quick relievers include:
- Short-acting beta agonists work quickly to relax the smooth muscles around the airways and decrease swelling. These medicines are the first-choice quick reliever.
- Anticholinergics open the airways by relaxing the smooth muscles around the airways and reduce mucous production. These medicines work slower than the short-acting beta agonist medicines.
- A combination of both an anticholinergic and a short-acting beta agonist is used as a quick-relieve medicine for asthma, too. It comes as an inhaler or a nebulizer for inhalation.
Apart from the medicines, the patient or the parents of the child patient should take an active role to control asthma, together with a doctor and other health care providers, by creating an asthma action plan. The plan should give guidance on medicines intake, avoidance of asthma triggers, physical activity control, asthma control tracking, responses to worsening symptoms, and emergency care.