Asthma

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Asthma is a condition in which the bronchial tubes of the respiratory tract are hyper-reactive. In response to various triggers, the airways constrict and get inflammed, resulting in the characteristic recurrent symptoms of asthma: (1) shortness of breath and/or (2) wheezing and/or (3) cough.

Currently, asthma is the most common chronic respiratory problem in children, and its incidence among Singapore children has doubled in the past 20 years. This increase in incidence is, in fact, a worldwide phenomenon. Whilst the exact cause for this is not known, the “hygiene hypothesis” suggests that because of “near-sterile” hygiene standards in early childhood, children who are less exposed to bacterial infections end up with an immune system which develops a more allergenic type response.

Asthma is largely an allergic disorder, which often occurs with allergic rhinitis (sensitive nose), allergic conjunctivitis (sensitive eyes) and eczema (sensitive skin). As with most allergic disorders, there is a significant hereditary component. So parents with atopy (sensitivity) are more likely to have atopic children.

ASTHMA TRIGGERS

Acute asthma exacerbations can be caused by a large number of environmental triggers. These may include food, viral infections and air pollutants. Exhaustive testing for asthma triggers is not cost-effective and is not usually necessary in the majority of patients.

Possible triggers include:

• the flu and other viral upper respiratory tract infections (being the most common triggers)
• house dust mites, animal dander, pollen and mould
• tobacco smoke, chemical fumes and scents
• air pollutants eg haze, smog
• cold weather
• drugs, most commonly the NSAID (non-steroidal anti-inflammatory drugs) group of drugs
• physical exertion
• emotional stress
• contrary to popular belief, food is rarely a trigger, unless tests prove otherwise

ASTHMA SYMPTOMS

The classic symptoms of asthma are:

• Wheezing
• Shortness of Breath
• Coughing (especially at night)
• Tightness in the chest

Acute exacerbations of asthma are episodes of progressively worsening of the above symptoms in isolation, or in some combination. The rate of progression is very variable and can range from a few minutes to a few days.

Oftentimes, these attacks are precipitated by some trigger, such as a viral infection, exercise or exposure to dust.

Wheezing is commonly associated with viral respiratory illnesses in young children (because they have small and narrow airways), and this symptom on its own, may not be due to asthma.

EXERCISE INDUCED ASTHMA

Exercise induced asthma Exercise is a common trigger of asthma. It may be the only trigger of asthma in some people, and can significantly limit their ability to engage in exercise and sports.

People with exercise-induced asthma are believed to be more sensitive to changes in the humidity and temperature of air. At rest, air is normally breathed in slowly through the nose, enabling the air to be sufficiently warmed and humidified before entering the lungs.

When one exercises, air is breathed in more rapidly, and through the mouth. The air that gets into the lungs, is thus cooler and drier. It is this cool and dry air that is believed to trigger an attack.

Fortunately, in those with only exercise-induced asthma, there is no need for maintenance therapy. Often, all that is required is inhaled ventolin prior to exercise. Whether you exercise occasionally or engage in competitive sports, exercise-induced asthma should not stop your activities.

DIAGNOSIS OF ASTHMA

Doctors make the diagnosis of asthma by taking a medical history and conducting a physical examination. By definition, asthma is characterized by recurrent or chronic wheezing and/or coughing, with variable airway obstruction due to bronchial hyper-sensitivity secondary to airway inflammation.

Hence, a clinical history of recurrent shortness of breath, cough, chest tightness or wheezing, especially if there is a family history of asthma, or associated symptoms of allergic rhinitis, allergic conjunctivitis or eczema, would point to a diagnosis of asthma. There may be physical signs such as rhonchi (wheezing) heard.

The diagnosis of asthma, however, in early childhood still remains a challenge for doctors, and is largely based on clinical judgement and an assessment of symptoms and physical signs. Occasionally, some tests are performed, such as spirometry and lung function tests, but these are difficult to perform in children younger than 5 years of age.

Your doctor may put your on a trial of treatment with short-acting bronchodilators (eg. Ventolin) and inhaled glucocorticosteroids. Marked improvement of symptoms supports the diagnosis of asthma.

ASTHMA MANAGEMENT

The goal of asthma treatment and management is to achieve and maintain good control, such that the patient has minimal symptoms (ie. No sleep disturbance, no early morning shortness of breath, no exercise intolerance), infrequent exacerbations, minimal need for bronchodilator therapy and can have normal physical activities.

An important aspect of asthma management, which should not be forgotten, is trigger avoidance. Appropriate medication together with trigger avoidance is key to managing asthma.

Medication used in asthma include:

“Reliever” medication – these are the short-acting bronchodilators which bring fast relief during an acute attack. They relax the muscles of the airways causing them to open up. May be administered as an aerosol spray, syrup or tablet.

“Preventer” medication – these medications are anti-inflammatory agents which help prevent acute asthma attacks. They are mostly low dose steroids, which may be used on their own (eg. Beclotide and flixotide) or in combination with long-acting bronchodilators (eg. Seretide and symbicort).

Montelukast – these are leukotriene receptor antagonists. These “sprinkle on” granules and chewable tablets are useful in children with mild persistent asthma. They also provide some protection in exercise-induced asthma and are effective as an add-on therapy in children whose asthma is insufficiently controlled on low-doses of inhaled steroids alone.

Oral steroids – used in short term treatment of acute asthma attacks.

Nebulized medication – your doctor may prescribe medication via a nebulizer for severe acute attacks. This machine pumps a continuous mist of medication, which is inhaled via a face mask. It often brings significant relief.

As the goal of asthma therapy is to achieve control, patients should periodically monitor that control has been achieved and maintained. This can be done via various tools such as the Asthma Control Test (ACT) – a symptom assessment questionnaire. Monitoring of control can also be done by testing lung function with spirometry and peak expiratory flow rates.

Whilst there is no cure for asthma, it is a very treatable disease in which good control can usually be achieved.

PREVENTERS vs RELIEVERS

Asthma medication are best classified as Preventers and Relievers.

Preventers:
These are medications taken daily over the long term to prevent acute exacerbations of asthma. If you find that you require frequent use of your reliever medication, it is likely that your asthma is poorly controlled and you should discuss the need for controller medication with your doctor.

Controller medications have an anti-inflammatory effect, reducing the inflammation and sensitivity of the airways use regular use.

Examples of controller medication are: Beclotide, Flixotide, and the newer generation long acting beta-2 agonists (LABA) such as Seretide and Symbicort.

Relievers:
Relievers are medication taken as required for quick relief of asthma symptoms. They are fast acting and work to reverse the constriction of the smooth muscles of the airways during an acute attack. It is important to note that relievers do not reduce the inflammation in the airways associated with an exacerbation.

The most effective relievers are rapid acting inhaled beta-2 agonists such as Salbutamol (Ventolin), but inhaled anticholinergics such as Ipratropium may also be used.

THE BENEFITS OF LONG-TERM PREVENTIVE TREATMENT OF ASTHMA

If you are constantly dependent on your quick relief medication to control your asthma symptoms, it is likely that you will require long term preventive treatment.

Asthma is a chronic disease, very much like diabetes and hypertension. A hypertensive patient takes his medication daily, regardless of symptoms, to control his blood pressure. He does not wait for his pressure to go out of control before he takes his medication. Management of persistent asthma should be no different.

The benefits of long term preventive treatment of asthma are clear.

1. Improved quality of life.
2. Reduced risk of emergency room visits.
3. Reduced frequency and severity of acute asthma attacks.
4. Reduced risk of hospital admissions.
5. Prevent loss of productivity from days missed at work/school.
6. Reduce total cost of asthma treatment in the longer term.
7. Reduce risk of death from asthma.

ALLERGEN AVOIDANCE TIPS

Asthma may be triggered by a wide range of environmental factors. Whilst complete avoidance of these triggers is impractical, identifying the common ones and taking simple measures to avoid them, can go a long way in helping keep your asthma under control.

Dust Mites:
House dust mite is a universal allergen. Whilst there is no single most effective method, the following steps, in combination, can help reduce exposure to mite allergens.

• Encase pillows, mattresses etc with allergen-proof, anti-dust mite covers.
• Wash all bedding and stuffed toys in hot water (exceeding 60 degrees Celcius) once a week.
• Avoid carpets, thick curtains and stuffed toys where possible.
• Use vacuum with integral, HEPA filters.
• Keep all clothing in drawers/closets to reduce dust collection.
• Clean all surfaces with a damp cloth regularly.
• Regularly change and clean air conditioner filters.
• Keep clutter under control.

Animal Dander:
Avoid keeping animals that shed fur. Animal dander is a well known trigger for asthma. If you already own an animal or are keen on keeping one, keep your pet away from your bedding and bathe your pet regularly.

Air Pollution:
Most studies show an association between air pollutants and asthma exacerbation. During periods of haze, patients with asthma should avoid strenuous outdoor activities.

Smoking:
Asthmatics should avoid smoking and exposure to second hand smoke.

Insect Control:
Many homes have cockroaches and other insects which may potentially trigger asthma.

• Use cockroach baits and traps.
• Insecticides may be used, but not in the presence of those who are asthmatic. Ensure that rooms are adequately aired before entering them.

Occupational Triggers:
The possibility of occupational triggers should be considered in adult onset asthma. It should also be considered in a known asthmatic if asthma appears to be made worse in relation to work.

The range of occupational sensitizers is very large and complex, and will require assessment by a specialist.

Food And Food Additives:
True food allergies are uncommon, and exhaustive testing for food allergies is usually impractical.

FREQUENTLY ASKED QUESTIONS ABOUT ASTHMA

How can I prevent an asthma attack?

Acute asthma attacks can be prevented by basically avoiding triggers and taking regular preventive medication.

Can pain relievers trigger an asthma attack?

Yes, the commonly used aspirin and NSAID (non-steroidal anti-inflammatory drugs) group of pain killers, are well known to trigger asthmatic attacks.

What are the side effects of bronchodilator medication?

The common side effects of medication such as ventolin are as follows:

• palpitations
• tremors
• headaches
• nervousness

The likelihood of these side effects increases with higher doses of medication used. Thus, inhaled medication causes far less side effects than orally ingested medication.

Can inhaled glucocorticosteroids cause a sore throat?

Common side effects of inhaled corticosteroid medication include oropharyngeal candidiasis (yeast infection), hoarse voice and dry/painful throat. By simply rinsing one's mouth or gargling after inhalation, one can reduce the incidence of these local side effects.

How can I find out what I am allergic to?

If you suspect you may have some allergies which may be triggering your asthma, see your doctor who may then recommend some investigations, such as a skin prick test.

Will my asthma affect my baby and are asthma medications safe in pregnancy?

Asthmatic patients who are pregnant should continue with inhaled medications, which have been shown to be generally safe. Acute asthma attacks can result in dangerously low oxygen supply to the foetus. Poorly controlled asthma is associated with pre-eclampsia, higher rates of caesarean section, pre-term delivery, intra-uterine growth retardation and low birth weight. These risks of uncontrolled asthma are significantly greater than the risks (if any) of necessary asthma medication.

Is it true that inhaled corticosteroids affect growth in children?

There are 2 important things to note in answering this question.

Firstly, uncontrolled asthma adversely affects the growth rate and final adult height attained.

Secondly, growth retardation (ie. rate of growth) is seen if high doses of inhaled corticosteroids are used especially in younger children (ages 4 to 10 years), however, the ultimate height attained is not affected (although it may be attained at a later age).

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