Asthma in children is an obstructive respiratory condition characterized by recurring attacks of wheezing, shortness of breath, prolonged expiration, and an irritated cough that is a common, chronic illness in childhood. Although the disease can begin in infancy, it is often difficult to diagnose asthma in young children. Nevertheless, these children require treatment.
The lung is the main organ of the respiratory system and its main function is respiration (exchange of gases between the environment and the body). Air enters the nose where it is filtered, warmed and humidified. After passing through the trachea (windpipe), the air travels into the lungs through the bronchi (a system of branching airway tubes that become smaller as they reach deeper into the lung). The smallest of the bronchi, the bronchioles, open into balloon-like sacs called alveoli.
An asthma attack occurs when these airways narrow and the muscles around them tightly contract (this is called bronchospasm). The membranes lining the inner walls of the airways become swollen and inflamed, and the glands within these walls produce excess mucus.
An asthma attack can be brief or it can last for several days.
Though not curable, asthma can be controlled by taking medication and by avoiding contact with environmental "triggers" for asthma.
There is a strong hereditary factor associated with the disease. Patients and their family may have a history of asthma, atopic dermatitis (eczema, an itchy skin rash), and allergic rhinitis (hay fever). In fact, a number of studies have shown that a majority of children who develop asthma have allergies as a trigger for the asthma. Often a child develops eczema, then develops allergic nasal symptoms ("hay fever") and then asthma. This progression has been termed the "allergic march".
The two main factors that contribute to asthma are inflammation of the airway passages and hyperreactive bronchi.
When triggered by stimulus (see examples below), certain cells lining the airways release chemical substances called mediators that lead to inflammation. This inflammation causes the airway passages to swell, the cells lining the passages to produce excess mucus, and the airway opening to narrow.
Hyperreactivity means that when the bronchi are exposed to stimulus they respond in an exaggerated way by constricting the airway muscle and making it difficult to breathe.
Some "triggers" that can induce an asthma attack are:
- allergens (substances to which people are allergic), such as pollens, foods, dust, mold, feathers or animal dander
- irritants in the air, such as dirt, cigarette smoke, gases and air pollution
- odors in the household, such as household cleaners, perfumes, paints, varnishes, fabric softeners, laundry detergents and cooking fumes
- irritants in the workplace, such as fumes and vapors from wood products and metals
- metabisulfite - a food preservative found in dried fruits, fruit juices, beer, wine, salad bars and vegetables
- respiratory infections, such as colds, flu, sore throat and bronchitis
- emotional stress, such as excessive fear or excitement
- weather conditions - very cold, windy or sudden changes in the weather
- medications, such as aspirin or related drugs, as well as some drugs used to treat glaucoma and high blood pressure
Nighttime - Asthma often worsens at night for a few reasons. The body releases chemicals during the night that may alter lung function. Also, the body's temperature tends to drop at night, which causes the airways to cool. Lastly, an exposure to allergens during the day may take up to several hours to affect the body. Asthma occurring during the nighttime (called nocturnal asthma) even if mild is considered dangerous because many asthma deaths occur during the early morning hours. If you or your child have even mild asthma symptoms during the night, it is important that you tell your doctor.
During an asthma attack, constriction of the airway and swelling and mucus secretion tend to close the smaller airways. To compensate, the person breathes at a higher lung volume to keep the air flowing through the airways. The greater the airway limitation, the higher the lung volume must be to keep the airways open. This process leads to the following symptoms of asthma:
- cough - chronic or recurring (worse particularly at night and in the early hours of the morning)
- pain or a tight feeling in the chest
- shortness of breath
- flaring of the nostrils when breathing in (especially in children)
- interrupted talking
- hyperinflation (appearance of hunched shoulders, hunching forward or preferring not to lie down)
Parents may notice their child has less stamina during active playtime than his or her peers. Or the child may limit his or her activity to prevent coughing or wheezing. The child may have heavy breathing, shortness of breath, and wheezing at rest or with exercise. These symptoms may be subtle and only recognized during activity.
If accompanied by infection, the child may have a fever, runny nose, and cough and be irritable.
The more subtle signs of asthma, such as chest tightness, may be overlooked or not identified by a child. In severe cases, the patient may have bluish skin around the lips and fingers.
The physician relies heavily on the observations of the parent for diagnostic clues, especially in young children. Recurrent or constant coughing spells, sometimes at night, may be the only sign of an asthmatic state.
Diagnosis is made by the medical history, including family history and symptoms, physical examination, and measurements of expiratory function with a peak flow meter.
Since a large number of children with asthma have allergic triggers for the asthma, allergy testing for inhalants (such as pollen, animal dander and dust mite) or foods should be considered.
Doctors advise patients of asthmatic children whose attacks are allergy-related to help the child avoid the allergens wherever possible, or more rigorous dust-control measures must be instituted.
Usage of a peak flow meter may be helpful, especially if the parents or child have difficulty recognizing the early stages of an asthma attack, or to track the progression of the disease.
The first steps in treating asthma are to diagnose the disease, and then to recognize the early signs of an asthma attack. If the symptoms are mild or occur infrequently (less than twice a week during the daytime or less than twice per month at night), a bronchodilator drug such as an albuterol inhaler or nebulizer may be all that is needed. However, since most children will have symptoms more often even though they are mild, a daily controller medication such as a corticosteroid in a nebulizer or inhaler, or an oral medication such as montelucast should be prescribed. Allergy immunotherapy (“allergy shots”) may be recommended if there is a reasonably clear indication that exposure to the allergen is a trigger for the asthma symptoms.
What is the probable cause of the asthma attacks?
Can you identify the "triggers" involved?
Is there evidence of a respiratory infection?
What is a peak flow meter, should my child be using one and how does my child use it? How often?
What is an inhaler? What is a spacer?
Is the child using the inhaler correctly?
Do you recommend use of a bronchodilator? When?
Does my child need to use a daily controller medication?
What further treatment do you recommend?
Allergic responses to perennial environmental allergens, such as dust, mold, or indoor pets, can worsen asthma and can be unrecognized because of the mistaken idea that children cannot develop allergy until they are several years old. It is essential that the child be protected from irritants, most importantly tobacco smoke. Chronic irritation of the airway of an asthmatic child exposed to secondary smoke may make asthma difficult to control.
Periodic assessments and ongoing monitoring of asthma are essential to determine if therapy is adequate. Children and their parents need to understand how to use a peak flow meter and to understand the symptoms and signs of an asthma exacerbation. Regular follow-up visits (at least every 3 to 6 months) are important to maintain asthma control and to reassess medication requirements.