Respiratory conditions - quality prescribing strategy: improvement guide 2024 to 2027

Appendix 2: When is a dry powder inhaler (DPI) suitable or not?

For patients with respiratory conditions who are interested and happy to try a DPI, it is suggested that a DPI device is a suitable option for those who can breathe in through their mouth quickly and deeply over two to three seconds.^[86]

Many patients may find DPIs easier to use, especially when given inhaler technique instruction,^[87] although teaching inhaler technique has positive impacts on disease and patient outcome for all inhalers.^[88] Factors such as older age affect inhaler technique but a review was not able to determine whether this was related to dexterity, cognition, physical ability, or the device.^[17]

In clinical use, DPIs perform as well as other types of inhaler device even during asthma or COPD exacerbations.^[79] This is irrespective of patient’s respiratory condition or age. Patient’s inspiratory flow does not limit the use of any inhaler type however there are patient beliefs and misconceptions^[79] that DPIs may be difficult to use when inspiratory flow is low. Previously, it was thought that DPIs were not an appropriate choice of inhaler for patients who are not able to generate sufficient inspiratory flow.^[89],[90] An In-check® device can be used to determine inspiratory flow if desired and this can be cross referenced to the manufacturer’s recommended minimum inspiratory flow rate for individual device types.

All inhalers are prone to technique errors. Correct inhaler technique, treatment adherence and patient preference has a greater impact on disease outcomes rather than the indiscriminate choice of a specific device.^[88],[91] pMDIs require the ability to co-ordinate actuation of the inhaler with a long slow inspiration, which can be a problem for some patients.^[89] A review highlighted that DPIs may not be suitable^[89] for the following groups:

• frail, elderly patients
• very young patients
• those with muscle weakness

A person-centred approach, checking inhaler technique and suitability of the device chosen is recommended for the groups highlighted above. Inhaler choices should be made with the patient,^[89] ensuring the right device for the right patient.^[92]

Individuals should have a reliever inhaler (DPI or MDI plus spacer) that they are able to use in the event of an acute exacerbation of asthma or COPD. If a patient has concerns regarding their ability to use their inhaler device during an exacerbation, this should be discussed, and a person-centred choice made. In this situation a single issue of a pMDI reliever plus spacer may be reasonable for use in an acute exacerbation. Table 14, SIGN 158^[6] Consider switch to pMDI with lower global-warming potential if this is clinically appropriate.

Reassure those for whom a DPI is unsuitable that the greenest inhaler is the one that they can use effectively to have good disease control, minimise the use of their reliever inhaler and avoid hospitalisation. Good control is better for the individual, and for the environment.