Childhood Asthma

A wheezing child has over 80% chances of having asthma. Though wheezing has been considered as a hallmark feature of asthma but it may be associated with other disorders. Recurrent wheezing in infants and children should be considered a diagnostic feature of asthma, but all asthma does not wheeze. Pulmonary function tests (PFT) should be performed to confirm a diagnosis of asthma. Non-wheezing asthma is called 'occult asthma'. Spasmodic, persistent or recurrent cough may also be a feature of asthma. In the absence of wheezing a diagnosis of asthma may be missed in children. All cases of suspected asthma should be subjected to PFT. The response to asthma therapy can also be assessed with PFT. General pulmonary fitness in-between attacks should be monitored at home or at doctor's clinic by Peak Expiratory Flow Rate (PEFR) meter. Various precipitating and aggravating factors may differ with age in children and the trend may continue during adult life.

Because of various misconceptions, asthma is highly undertreated disorder in children. Symptoms of asthma may vary with age and asthmatic children always have different clinical patterns. Type and duration of pharmacotherapy appropriate for one pattern may be inappropriate for the other, so it is important both for the physician and the parents of children to understand these patterns.

Childhood Asthma: Pattern-I

Allergic, viral or exercise induced asthma are included in pattern-I. Here the chest congestion with wheezing and breathlessness (bronchospasm) occurs in minutes or hours and rarely lasts for more than a few days. Around 50% percent of all cases of childhood asthma have pattern-I asthma. There may be 1 to 5 episodes per year. The lung functions are near normal and these cases respond well to bronchodilators along with anti-allergic treatment and rarely need steroids.

Childhood Asthma: Pattern-II

Aetiology and features of this type also resemble pattern-I but number of attacks may be 5 to 6 per year. Longer duration of treatment with bronchodilators and sometimes steroids may be required.

Childhood Asthma: Pattern-III

Undertreated children may develop this pattern where overt symptoms of asthma may be variable with impairment of PFT. These children require steroids along with bronchodilators and the course of treatment may be longer.

Childhood Asthma: Pattern-IV

Children with this pattern experience breathlessness without considerable wheezing. Variable but persistent airway obstruction and impaired PFT have been documented in children affected by pattern-IV asthma. These patients need long term treatment with bronchodilators and steroids.

Childhood Asthma: Pattern-V

Children having no symptoms of asthma during the day but having asthmatic attack at midnight or early in the morning should be labeled as the cases of pattern-V asthma. These patients may need aerosol therapy with steroids or beta agonists at night to control the cough and wheezing. Concurrent exposure to various aggravating factors may induce severe effects. Aggravation of symptoms by exercise or a specific allergen should be recognized and reported to the treating physician.

Management of Asthma

The asthma means bronchospasm and for its effective management we need bronchospasm relaxants. There are a variety of preparations containing sympathomimetics in the form of aerosols, inhalations, tablets and syrups capable of producing bronchodilations by stimulating b₂-adrenergic receptors in the bronchial smooth muscle. The choice and mode of treatment depends on the age of patient and severity of asthmatic conditions. Inhalations and aerosols may not be convenient mode of treatment in infants and children. Salbutamol and terbutaline are relatively selective drugs for b₂-adrenergic receptors. These produce optimal bronchodilations at lower concentration than those required to stimulate b₁-adrenergic cardiostimulatory receptors. Respiratory stimulants like doxapram and nikethamide are of no value and may be harmful in cases of asthma. As per the experience of a close friend of mine, sympathomimetics like salbutamol and terbutaline produce immediate relief in reversible bronchospasm associated with asthma and allergic bronchitis. Excessive and long term use of these drugs may cause cardiac arrhythmias.

Xanthine derivative drugs such as aminophylline, theophylline and etophylline are known to produce smooth muscle relaxation and bronchodilation by inhibiting the enzyme phosphodiesterase which leads to an increase in the intracellular levels of cAMP. Xanthine derivatives also produce diuresis (increase in the urinary output) and cardiopulmonary stimulation. Corticosteroids as aerosol inhalation help to reduce the mucosal edema, hypersecretion of mucous and bronchial hypersensitivity. Corticosteroids act by preventing the release of phospholipids from cell membranes in the lungs and their anti-inflammatory action helps to underplay the mediators of inflammation. Oral corticosteroid therapy should be reserved for acute exacerbations and chronic cases but after the radiological evaluation of lungs and investigations of sputum for Mycobacterium tuberculosis (tubercle bacilli or TB) and other bacterial or fungal infections. Asthmatic patients should avoid total dependence on aerosols or inhalations and should ask their physicians to prescribe them oral drugs also for emergency use. A combination of salbutamol and aminophylline or theophylline as tablets or syrup is a reliable form of treatment for asthma advisable under the guidance of a medical practitioner only.