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Editorial Indian Pediatrics 2002; 39:719-723 |
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Current Perspectives in Management of Chronic Asthma in Children |
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Asthma in children is very common, with up to 40% of children at 5-6 years of life reporting symptoms consistent with asthma (6). However, not all children with asthma require preventive therapy. The Australian National Asthma Council Asthma Management Handbook (7) recommends that preventive therapy should be commenced when:
The clinical pattern of the child’s asthma is the key to determining the need for preventive therapy. In this regard, a thorough and accurate clinical assessment of the child’s asthma, especially at times when the child is between attacks and thought to be well is essential. In Australia, we found that encouraging the asking of specific questions about: the number of days on which symptoms occurred between attacks; the number of night sleep was disturbed due to asthma; the number of days b2-sympathomimetics were required; and activity limitation due to asthma (2) were helpful in assessing the need for preventive therapy. Inhaled corticosteroids are the most effective preventive therapy for children with moderate-severe chronic asthma (8). Children with mild persistent asthma may respond to non-steroid medications such as the cromones (sodium cromoglycate and nedocromil sodium), however, if their asthma is not controlled within 2-4 weeks, they should be switched to inhaled steroids (8). The cromones are not as effective as inhaled steroids (9) but may be worth considering if the child’s family is strongly against the use of steroids and the child’s asthma is not too severe. While concern has been expressed that a delayed introduction of inhaled steroids in children with even mild persistent asthma may result in an irreversible loss of lung function (10, 11), this has been shown not to be the case in the large childhood asthma management program or CAMP study from the USA. The CAMP study did show an improvement in asthma control, a reduction in use of b2-sympathomimetics and oral steroids and reduction in "urgent care" visits in children treated with preventive medication compared to those treated with placebo, supporting the recommendations of the Australian NAC. While data in children comparing the effectiveness of leukotriene receptor antagonists with that of inhaled corticosteroids, either alone or in combination with long-acting b2-agonists are few, several studies including children over the age of 12 to 15 suggest that the role of leukotriene receptor antagonists is limited. Patients with moderate asthma and persistent symptoms despite low-dose inhaled steroids were randomised to receive either fluticasone/salmeterol through a Diskus inhaler or inhaled fluticasone +oral montelukast. The group treated with the fluticasone/salmeterol combination achieved significantly better asthma control, both in terms of lung function and days free of symptoms (12). A recent study comparing switching asthmatics, aged 12 years and older, whose asthma was stable but still symptomatic on inhaled beclomethasone (or triamcinalone), to either the leukotriene receptor antagonist, zarfirlukast, or inhaled fluticasone demonstrated superior asthma control with fluticasone but deterioration with zarfirlukast (13). TABLE I– Recommendations for Age Appropriate Delivery Devices
One potential advantage of oral therapy for asthma prevention is claimed to be that children will find it easier and thus will be more likely to take it. However, a recent study (14) measured the adherence to oral montelukast and inhaled fluticasone in children taking part in an open-label study. Sherman et al demonstrated that while the adherence was a little higher with montelukast (mean 59% [95% CI 48-65%]) than with fluticasone (mean 44% [35-50%]) it was poor with both medications. Thus simply prescribing an oral treatment will not guarantee that the child will take it. The current treatment recommendations in Australia are to start children with moderate-severe persistent asthma on an initial dose of 400 mg/day of beclomethasone diproprionate (CFC propellant) or budesonide or 200 mg/day of fluticasone propionate, with the dose back-titrated to maintain adequate asthma control with the lowest dose possible (7, 8). A significant change has occurred in the use of inhaled steroids in Western countries in recent years, brought about by two factors: the realisation that the dose-response curve for inhaled steroids is quite flat (ie higher doses do not necessarily produce greater responses) and the availability of long-acting b2-agonist. In children whose asthma is not controlled on the recommended doses of inhaled steroids, superior asthma control is achieved by the addition of a long-acting b2-agonist than by doubling the dose of inhaled steroid (8). The scientific rationale for this practice has recently been reviewed (15) and includes a two-way beneficial interaction between inhaled corticosteroids and long-acting b2-agonists. The place for additional therapies, such as theophylline and leukotriene-receptor antagonists would appear to be as third-line therapy for those who have not responded adequately to the combination of inhaled steroids and long-acting b2-agonists. An important factor in achieving good asthma control in children with chronic asthma is ensuring adequate drug delivery to the lungs. An unfortunate reality of asthma management in children is that not all delivery devices are suitable for children of all ages and that children will require different delivery devices as they grow (16). While jet nebulizers can be used at any age, they are inefficient devices and expensive to buy. The use of nebulizers and nebulized medications has been rising at a rapid rate in India (Khubchandani, personal communication, 2002). The major concern with this trend is that it implies a reliance on symptomatic treatment with short-acting b2-agonists rather than on preventive therapy. For the reasons discussed above, this is the wrong emphasis and one that paediatricians should work to overcome. The place of nebulizers and nebulized medications in home management of asthma, especially in preventive therapy, is questionable and not generally recommended (2, 7). The real choice for preventive therapy is between a pressurised metered-dose inhaler (pMDI), used with an aerosol-holding chamber (or spacer) and a dry powder inhaler device (DPI). Children under the age of 5-6 years cannot generally use a DPI and should be treated with a pMDI + spacer. Children who are too young to reliably breathe through a mouthpiece (generally under the age of 2-3 years) should use a small volume spacer (approximately 200-250 ml) with a face mask (17). The small volume spacers will result in greater drug delivery to the lungs as these young children do not have the tidal volume required to empty the drug from a large volume spacer within a reasonable time. As soon as children can be taught to breathe from a mouthpiece, they should be switched to a large volume spacer with mouthpiece. Children breathing through a facemask are likely to breathe through the nose, resulting in less drug delivered to the lungs as this is filtered by the nose (18). The choice of a suitable DPI will depend on the child’s age and the inspiratory flow through the DPI required to deliver drug to the lungs. DPI with a low-resistance mouth piece, such as the accuhaler require relatively low inspiratory flows for drug delivery, with delivery relatively constant for inspiratory flows from 30 to 90 litre per minute. In contrast drug delivery from a DPI with a high-resistance mouthpiece, such as the turbuhaler, increases progressively with increasing inspiratory flow - or more importantly is likely to decrease if the inspiratory flow a child can generate falls, as is likely with an acute asthma attack (19). The Australian NAC (7) recommendations for age-appropriate delivery devices are summarised in the Table I. An important part of managing children with chronic asthma is to reduce their exposure to environmental factors that may trigger their asthma. The most common triggers are viral upper respiratory infections. These, of course, can not be avoided. The trigger factor most easily avoided is environmental tobacco smoke (ETS). Children with asthma should not be exposed to ETS in their homes or in confined spaces, such as motor vehicles. Control of indoor allergens is more problematic and measures that work in one country may not be effective in another. In Australia, the predominant allergen is house dust mite; most effective reduction measure is using occlusive covers on the child’s mattress and pillow, however data should be collected in India to show that this is also effective locally before recommending such measures. In summary, management of children with chronic asthma should be centred around: accurate assessment of the need for preventive therapy; use of inhaled steroids plus long-acting b2-agonists for those who do not respond to the recommended doses and ensuring adequate drug delivery by the use of age-appropriate delivery devices. Funding: None. Competing Interests: None declared. Peter D. Sly, Professor and Head, Division of Clinical Sciences, Telethon Institute for Child Health Research and Center for Child Health Research, University of Western Australia, PO Box 855, West Perth, Australia
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