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Asthma inhaler devices for children

There is no single best inhaler device although depending on the patient's age some are more appropriate than others. Charles Broomhead explains how to treat children with asthma and what types of inhalers are available

Charles Broomhead
MB ChB FRCGP DA DRCOG
GP
Sutton Coldfield
GP Trainer and Honorary Clinical Lecturer
Birmingham University

Asthma is a common problem with an estimated and increasing prevalence in England of between 10% and 23%. Not all children have had their condition recognised and not all are receiving treatment. Notwithstanding this approximately 9% of boys and 6% of girls under the age of five years are prescribed inhalers, while in those aged 5-15 years, the corresponding figures rise to 12% and 10%.(1)
With a very few exceptions, where a choice exists, asthma is best treated with drugs that are inhaled rather than taken by mouth. There are several good reasons for this. Not only does the medication reach the lungs quickly while minimising the potential for unwanted systemic side-effects, but also by administering it in this way it is generally possible to use significantly smaller doses than would otherwise be the case.
Basic considerations
There are a number of fundamental issues to consider when treating a child with asthma. The diagnosis must be correct, the appropriate medication, be it a "reliever", "preventer" or a combination of both, must be chosen and a suitable delivery device must be selected. By suitable I mean that the child must be able to use it correctly and it must be acceptable to both them and their carer. In other words they must be prepared to use both the type of medication that has been prescribed and the inhaler that delivers it.
Importantly the device must produce consistency and reproducibility of dosing to minimise variation in the quantity of drug that is delivered to the lungs. This is a situation where one size does not fit all and the cheapest option is not necessarily the best one. If there is more than one effective choice, however, it is sensible to try the least expensive option first. Even when treatment has been successfully established it must be kept under regular review. It cannot be assumed that the best inhaler today will automatically be the best choice in the future.

Types of inhaler
There are three main types of inhaler device from which to choose. These are the "press and breathe" pressurised metered-dose inhalers (pMDIs), the breath actuated pressurised metered-dose inhalers and dry powder inhalers (DPIs). pMDIs are often used in combination with spacer devices, which themselves can be of different volumes. These attachments are designed to deal with some of the problems associated with the use of certain inhalers. Approximately 60% of childhood asthma medication is delivered by pMDIs.(1)
More than 70 different possible inhaler choices and at least five different spacers are licensed for use by children in the UK. To confuse matters further, with the advent of CFC-free devices, not all versions of the same drug have paediatric licenses. For example, beclometasone as Qvar [IVAX] is not recommended for those under 12 years, but as Clenil Modulite [Trinity-Chiesi] it has no comparable restrictions.
Some inhalers have counters that indicate how many doses remain, which make it possible to check whether the medication is being used regularly.
Spacer devices come in a variety of forms and are made from either plastic or metal. Some are "generic" in their ability to fit several different brands of pMDIs while others will only work with specific inhalers. While the idea of a "universal" device may seem attractive, some doctors and nurses have concerns that the delivery of medication may not be as reliable and predictable as when a spacer and inhaler that have been designed to work together are used.
The consequences of poor device selection may be profound, from diminished quality of life and unnecessary surgery attendances, to the more serious hospital admission or even death. Ineffective or inappropriate therapy is expensive, not simply in terms of the waste of expensive medication, but also as a result of the additional care and investigations that may become necessary.

Which inhalers work best?
Research has shown that, depending on the device and other factors, such as how well it is used, there is a huge variation in the amount of medication that actually reaches the lungs - estimates range from 6% to 60%.(2)
NICE has published guidance on the selection and use of inhaler devices for children under the age of five years and also for older children between the ages of five and 15 years.(1,3) Both provide sound, evidence-based advice and are good reference sources. SIGN (Scottish Intercollegiate Guidelines Network) Guideline No 101 was published in May 2008 in collaboration with the British Thoracic Society (BTS) and, among many other things, contains sections on the selection, use and care of devices.(4)

Children aged less than five years
All MDIs need at least some coordination of actuation and inhalation by the user and may be difficult to use, especially in young children. For this reason, in the case of infants, there is little choice but to use an MDI with a spacer device and a mask. The spacer acts an intermediary chamber into which the MDI is discharged, allowing the child to inhale the medication over several breaths. The MDI and spacer combination delivers inhaled medication very effectively, needing no coordination in its use. Parents should understand how well it works and how effective it can be if symptoms worsen. Although the electric nebuliser used in a GP surgery or hospital casualty may appear more impressive and prompt questions about buying one for home use, the reality is that an MDI and spacer work as well for most patients and cost infinitely less.
There is no clear benefit of using one type of spacer rather than another but the amount of medication that is delivered may vary considerably depending on the static charge that is present in the chamber. The best way of minimising this effect is to wash the spacer in household detergent and allow it to dry naturally rather than using a towel to do so. (Rubbing is what actually produces the charge.) Metal spacers may overcome this problem by not generating the charge in the first place.
NICE recommends that children under the age of five years with chronic stable asthma should generally receive their medication (both corticosteroids and bronchodilators) by means of an MDI and spacer with the addition of a facemask when necessary. It acknowledges that nebulised therapy may need to be considered in some circumstances and that exceptionally, dry powder devices may be appropriate in children aged between three and five years.

Children aged over five years
The principles of device selection in an older child remain the same, although there are additional options and other considerations to take into account. As the child grows up their personal views and preferences become more important and can have a crucial effect on their willingness to use a particular inhaler. Peer pressure becomes increasingly important as does the "street cred" of the chosen device.
pMDIs with a spacer remain the recommended firstline choice for delivering inhaled corticosteroids. Provided that the child complies with the therapy this is a good choice for delivering optimal preventive treatment. The relatively large size of a spacer makes portability difficult, but as most prophylactic medication is administered twice daily in itself this represents only a small barrier to its use.
Relief medication by definition needs to be portable and although there are some small spacers, this is generally not the best option. A wider range of alternative devices should be considered although it is wise to keep a pMDI and spacer in reserve for use in an emergency situation.
An estimated 50% of those who use a pMDI without a spacer have some difficulty in doing so. Considerable improvement will occur as a result of teaching and reinforcing correct inhalation technique, but for many, treatment will be suboptimal.
Breath-actuated MDIs overcome some of the problems associated with PMDIs. They automatically deliver a dose of medication when the user breathes in, thus avoiding coordination difficulties. While their mode of operation makes them unsuitable for use with a spacer, their small size makes them a good choice for an inhaler to carry around.
DPIs contain no propellant gas but rely on the user to breathe in sharply and thereby transport the medication to the lungs. As with breath-actuated inhalers, they overcome problems of coordination, but for some, particularly small children, the inspiratory flow may not be great enough to be effective. Some users may dislike the taste of the "carrier" powder that is used to enhance their efficacy. DPIs tend to be significantly more expensive than other inhalers.

The role of the practice nurse
Most asthma care takes place within primary care and the practice nurse is one of the most important components within this environment. When asthma treatment is unsuccessful the cause can often be identified as a failure of understanding or compliance on the part of the patient or his carer. Taking care to explain the nature of the condition and the rationale for the different types of medication is fundamental in improving outcomes, as is the selection of the most appropriate sort of inhaler for an individual patient.
Some inhalers are easier to teach patients to use than others and we all have favourites that we are biased towards prescribing. In spite of this we should resist the temptation simply to tell patients what they should do, as involving them in decisions about their treatment, including the choice of inhaler, is likely to greatly improve concordance.
It's important to remember that it takes time to check that a patient is able to use his inhaler and this is something that must be reviewed and checked regularly. Simply asking whether "they can do it" is not good enough and their technique should be observed whenever possible.

Conclusion
Good asthma care should include careful selection of both medication and inhalation devices. There are a number of basic principles that guide inhaler choice, but the final selection will depend on many factors including the patient's individual ability and preference.
There is no single best device but depending on the patient's age some are more appropriate than others. Regular review is essential as poor technique is a common cause of treatment failure, and the inhaler that appears the best choice today may not be the best choice in a few months time.

References

  1. National Institute for Health and Clinical Excellence. Inhaler devices for routine treatment of chronic asthma in older children (aged 5 - 15 years). Technology appraisal guidance - No 38. London: NICE; 2002.
  2. Le Souef P. The meaning of lung dose. Allergy 1999;54:S93.
  3. National Institute for Health and Clinical Excellence. Guidance on the use of inhaler systems (devices) in children under the age of 5 years with chronic asthma. Technology appraisal guidance - No 10. London: NICE; 2000.
  4. British Thoracic Society/Scottish Intercollegiate Guidelines Network. British guideline on the management of asthma. SIGN Guideline No 101.  Edinburgh; SIGN; 2008. Available from: http://www.sign.ac.uk/pdf/sign101.pdf