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Asthma inhalers: correct technique really matters

Choosing the right asthma inhaler can be a bewildering process for the healthcare professional. In this article, Stephanie Wolfe looks at the types of inhaler available, factors to consider when selecting a device and the importance of checking technique

Stephanie Wolfe
MSc RGN Dip
Independent Respiratory Nurse Specialist (Primary Care)
Norwich, Norfolk
General Practitioners Airways Group (GPIAG) Nurse Lead Education for Health Trainer

For many years, the inhaled route has been the preferred method of administering medication for the treatment of respiratory disease. This comprises primarily bronchodilators and inhaled corticosteroids (ICS). The inhaled route generally minimises systemic side-effects as the drug is delivered direct to the site of action and smaller doses can be used. Bronchodilator onset of action is also more rapid via the inhaled route, giving prompt, speedy relief.

Asthma continues to be a common condition, affecting people of all ages. Chronic obstructive pulmonary disease (COPD) is also common and increasing in incidence due to the legacy of long-term smoking, and as recognition and diagnosis improve. Inhalers are an essential part of the management of both these conditions.

Over the last decade, treatments for asthma have improved, along with the development of a wider range of inhaler devices. The British Thoracic Society (BTS) guidelines on asthma management state that most patients with asthma should be able to achieve optimal control of symptoms and
lead a life where activity is unrestricted by their asthma.1

Despite improved therapies and a wide range of inhaler devices, morbidity in asthma remains high.2 Key reasons for this are underdiagnosis, undertreatment, poor management, poor compliance and poor inhaler technique. It is easy to become complacent about inhaler technique and to assume that prescribed inhalers will be used correctly. Various studies have shown that inhaler technique is often very poor.3,4 When inhaler technique was checked it was found that only 23–43% of patients using a pressurised metered dose inhaler (pMDI); 53–59% using a dry powder inhaler (DPI); and 53–57% using a pMDI plus spacer could demonstrate inhaler technique without making any mistakes. This reinforces the BTS guidance on asthma management, which states that inhaler technique should be checked at every asthma review. If asthma control is found to be suboptimal, inhaler technique should be assessed before stepping up treatment.1

Even in long-term management, technique should always be checked as part of an asthma review, as it is easy to develop poor technique over long-term use.

For optimal inhalation and deposition in the airways, particles need to be 2–5 microns in diameter.5 Larger particles are deposited in the mouth and oropharynx, and this can account for around 90% of the particles in an aerosol. The route that these particles need to follow to reach the airways is somewhat tortuous, with many changes in direction due to the anatomical structure of the respiratory tract. Add poor technique to this and deposition becomes extremely poor. Various delivery devices are available; all are dependent on inhaler technique to some degree if maximum benefit from the medication is to be achieved.

Types of inhaler
Inhaler devices can be broadly classified as:

  • Pressurised metered dose inhalers (pMDI).
  • Breath-activated pMDI (BA MDI).
  • Dry powder inhalers (DPI).
  • Soft mist inhaler (SMI).

Pressurised metered dose inhaler
The pMDI has been available for a long time and is a device that many patients are familiar with and may expect to receive. It is often referred to as a "puffer". Prescribers, too, are often familiar with the pMDI. This type of inhaler is the most commonly prescribed inhaler device. It has the advantages of being available in most drugs, generally cheaper than alternative devices, popular with patients and easy to carry around. Sadly, the pMDI on its own is also the most incorrectly used device, giving poor delivery of the drug to the lungs and subsequent poor symptom control. Therefore, while it is the cheapest choice, it is not necessarily the most cost-effective.

Correct use of the pMDI is dependent on the patient's ability to co-ordinate breathing out fully and then breathing in gently and steadily while firing the aerosol spray. Breath holding is then essential for sedimentation of the drug particles within the airways. Users commonly have poor co-ordination, causing the inhaler to "backfire" with a visible mist escaping from the top of the inhaler or around the mouth if there is a poor seal.

Practising in front of a mirror is helpful in correcting this problem. Other errors include breathing in too quickly, failing to hold breath and actuating the device more than once for each inhalation.

Most pMDIs do not have a dose counter, making it difficult to judge when the inhaler is empty. Therefore, it is advisable to have a spare available.

Some patients may experience the "cold freon" effect as the spray impacts on the oropharynx, resulting in cough. The newer CFC-free inhalers tend to be warmer and fire more slowly than original CFC-containing inhalers and may help to overcome this problem. Alternatively, a spacer device could be used or switch to DPI.

pMDI plus spacer device
pMDI plus a spacer device is the most reliable method of optimal and safe delivery of an aerosol drug to the lungs and is recommended as firstline choice.1,6 However, this method is often not acceptable to patients and spacers frequently remain in their packaging unused!

Spacers are available as large-volume (VolumaticTM) or small-volume spacers (AerochamberTM). Most have the option of a mask. Advantages of using a pMDI plus spacer include:

  • No need for co-ordination.
  • Not dependent on inspiratory flow rate as tidal breathing may be used.
  • Suitable for the very young, elderly or disabled.
  • Effective in delivery of high-dose bronchodilators in acute breathlessness.
  • Minimises risk of local (dysphonia, oral thrush) and potential systemic side-effects when prescribing ICS, especially when higher doses are needed.

Disadvantages of pMDI plus spacer include:

  • Bulky and indiscreet, not easy to carry around.
  • Additional prescription charge (for some patients).
  • Unacceptable to some patients.

Electrostatic charge may be a problem with plastic spacers. Knowledge of care, washing and replacement is essential.

Breath-actuated MDI
Breath-actuated devices, such as the Easi-breatheTM and AutohalerTM, overcome the problem of co-ordinating inspiration with actuating the device, as they do this automatically at the correct point during inspiration. They do tend to be slightly bulkier and more costly than the standard pMDI. Careful instruction in cleaning these devices is essential, as parts of the mechanism could be damaged by immersion in water. Unfortunately, the range of drugs that can be used with this type of device is limited.

[[Box 1 asth]]

Dry powder inhalers
These devices are dependent on quite forceful inspiration to de-aggregate the drug into a particle size suitable for inhalation.5 Consequently, technique for using a DPI is very different to the pMDI. Some DPI have a lactose carrier that aids in deaggregation and also gives the patient feedback (a sweet taste) that a dose has been delivered. However, this only demonstrates that the dose has been delivered to the mouth; not necessarily reaching the lungs. Delivery of drug to the lungs is very much dependent upon patient effort and technique.

DPIs generally require some manual dexterity in preparing them for use. There is a wide range of DPIs currently available (see Box 2); the specific manufacturer's instructions should be followed and adhered to. These devices are often popular with young people as they find the "gadget" characteristics of the device appealing. DPIs are also quite discreet, portable and usually have a counter, making it easier to gauge when a prescription for a new inhaler should be requested.

[[Box 2 asth]]

Disadvantages of DPIs are that they are susceptible to damp and they are generally more costly than standard pMDIs. As these devices are dependent on an optimal inspiratory flow rate, there may be concerns that the drug dose will be decreased if inspiratory rate is reduced, as in worsening asthma or COPD (and poor inhaler technique).

Soft mist inhalers
This type of inhaler is relatively new, with only one device currently available in the UK (RespimatTM) for use in COPD. As the name suggests, the device creates a soft mist for inhalation. Co-ordination is still important; the mist is released quite slowly: a slow and gentle inhalation technique is required.

Device selection
With so many devices available, the task of selecting a device with a patient may seem a daunting prospect. Whichever device is chosen, the patient, parent or carer should know how to use it correctly, how to wash and store it and when to replace it. Demonstration of technique should be carried out whenever possible and reading the patient information instructions encouraged.
Factors to consider when selecting a device include the following:

  • Drug to be prescribed – which device(s) is it available in?
  • Delivery of consistent reliable dose.
  • Does the patient already use an inhaler? More than one type of device may complicate regimen.
  • Age and manual dexterity of patient.
  • Easy to use.
  • Ability to understand and comprehend instructions.
  • Does the device need to be easily portable?
  • Inspiratory flow rate.
  • Peer pressure.
  • Patients often like a device to have a counter.
  • Cost.

With so many factors to consider, a balance must be found between following recommendations from official bodies, such as the National Institute for Health and Clinical Excellence (NICE);6 BTS asthma guidelines;1 local or practice formularies and patient choice and preference. To reach a satisfactory, balanced outcome, health professionals need to have up-to-date knowledge of the many devices available. This will hopefully lead to improved symptom control and, in turn, improved quality of life for our patients.

References
1. British Thoracic Society Scottish Intercollegiate Guidelines Network. British Guideline on the Management of Asthma. Thorax 2008;63(Suppl 4):iv1–121. Available from: http://www.sign.ac.uk/pdf/sign101.pdf
2. Rabe KF, Vermeire PA, Soriano JB, Maier WC. Clinical management of asthma in 1999: the Asthma Insights and Reality in Europe (AIRE) study.
Eur Respir J 2000;16:802–7.
3. Crompton GK. Problems patients have using pressurized aerosol inhalers. Eur J Respir Dis Suppl 1982;119:101–4.
4. Brocklebank D, Ram F, Wright J et al. Comparison of the effectiveness of inhaler devices in asthma and chronic obstructive airways disease: a systematic review of the literature. Health Technol Assess 2001;5:1-149
5. Bell J. Why optimise inhaler technique in asthma and COPD? British Journal of Primary Care Nursing 2008;2(2):37-9.
6. National Institute for Health and Clinical Excellence (NICE). TA10 Asthma (children under 5): inhaler devices: guidance. London: NICE; 2000. Available from: http://www.nice.org.uk/guidance/index.jsp?action=article&o=32074

Resources
General Practitioners in Airways Group (GPIAG)
W: www.gpiag.org
Asthma UK
W: www.asthma.org.uk
ADMIT (Aerosol Drug Management Improvement Team)
W: www.admit-online.info

Further reading
Education for Health. Simply Devices: A Practical Pocketbook. Warwick: Education for Health; 2006.