Professor Henry Chrystyn highlights the importance of checking inhaler technique, and the common difficulties patients with asthma encounter when using these devices

It has been shown that good inhaler technique is associated with better control of asthma,1–3 reduced use of inhaled corticosteroids, and significantly fewer acute exacerbations and hospital admissions.4 However, patients who have been prescribed inhalers may have problems with treatment compliance5-8 and performing the correct administration technique.9 National guidance therefore recommends that compliance and inhaler technique are checked prior to altering either dosage or inhaler device, and that instructions on correct administration of therapy should be provided regularly by a highly trained healthcare professional.10,11 Treatment compliance can be improved by patient education12 and satisfaction with the device,13 while training helps with inhaler technique;1,14 however many patients do not retain the trained method so regular inhaler technique checks are required.15

Background

The problems that patients have with the use of pressurised metered dose inhalers (pMDIs) were identified almost 50 years ago16-18 and still persist today.3 Dry powder inhalers (DPIs) were introduced to overcome these problems, but difficulties with administration of therapy have also arisen with these devices.19 The problems that patients with asthma encounter when using their inhalers have been emphasised by the Aerosol Drug Management Improvement Team (ADMIT) group20,21 and the International Primary Care Respiratory Group.22 A joint European Respiratory Society and International Society for Aerosols in Medicines (ERS/ISAM) Task Force was formed to raise awareness of these issues and highlight the inhalation techniques that patients should be trained to use.9 This article presents common problems that arise when patients use inhaler devices and advises on the techniques that all individuals should be trained to use.9

Pressurised metered dose inhalers

It has been shown that only 8% of adults with asthma are able to use their pMDI correctly, with a slow inhalation flow and good coordination.1 Both subjective assessments and objective measurements4,6,17,18,23 have highlighted errors that can occur when people use pMDIs, including ‘failure to coordinate actuation and inhalation’ (27% of users).24 Studies have also shown that reduced lung deposition of inhaled therapy can occur as a result of poor coordination between inhalation and actuation:25

  • when people do not exhale before an inhalation26 (exhaling before an inhalation increases lung deposition; many patients do not exhale before they use their inhaler4)
  • when a fast inhalation flow is used27,28
  • when individuals do not hold their breath after inhalation.27

The generic method for using a pMDI and breathe-actuated pMDI, as recommended by the ERS/ISAM Task Force is described in Box 1.9 It defines the traditional instruction of a slow and deep inhalation by a period of time. It is recommended that the inhalation phase should take 4–5 seconds in an adult, and 2–3 seconds in a child.9 The patient should be encouraged to perform a relaxed inhalation, and told that the dose should be actuated soon after they begin their slow inhalation. A recent study has confirmed that training patients to prolong their inhalation phase increases inhalation time without affecting the inhalation volume and so the inhalation flows are reduced, which is beneficial.1,29

Some pMDI products emit particles that are extra-fine and it has been shown that lung deposition of such very small particles is not affected by the inhalation flow.28 Furthermore studies have shown that for these extra-fine particle products coordination is not critical30 and so an early or late actuation is acceptable. In theory, this suggests that products with a formulation of extra-fine particles are less affected by a poor inhalation technique, but the clinical significance of this has not been studied. Some beclometasone and ciclesonide pMDIs emit extra-fine particles.


Box 1: Detailed instructions on how to use pMDIs, BA-pMDIs, pMDIs with spacers, and DPIs9

pMDIs: for patients with good actuation–inhalation coordination
1) Shake four or five times if suspension formulation.
2) Take the cap off.
3) Prime the inhaler (refer to the patient information leaflet for specific instructions).
4) Exhale slowly, as far as comfortable (to empty the lungs).
5) Hold the inhaler in an upright position.
6) Immediately place the inhaler in the mouth between the teeth, with the tongue flat under the mouthpiece.
7) Ensure that the lips have formed a good seal with the mouthpiece.
8) Start to inhale slowly, through the mouth and at the same time press the canister to actuate a dose.
9) Maintain a slow and deep inhalation, through the mouth, until the lungs are full of air. This should take an adult 4–5 seconds.
10) At the end of the inhalation, take the inhaler out of the mouth and close the lips.
11) Continue to hold the breath for as long as possible, or up to 10 seconds before breathing out.
12) Breathe normally.
13) If another dose is required, repeat steps 4–12.

BA-pMDIs: for patients ?6 years old
1–7) Same as above for pMDIs alone.
8) Start to inhale slowly, through the mouth. The patient should sense that a dose has been released, either by taste or a noise when the dose is released (the noise is quiet for the Easi-Breathe®).
9) Maintain a slow and deep inhalation, through the mouth, until the lungs are full of air. This should take a child
2–3 seconds, and an adult 4–5 seconds.
10–13) Same as above for pMDIs alone.

pMDI + spacer with mouthpiece: for patients ?6 years old (caregiver should determine if child can perform this technique correctly)
1) Shake four or five times if suspension formulation.
2) Take the cap off.
3) Prime the inhaler (refer to the patient information leaflet for specific instructions).
4) Insert the mouthpiece of the pMDI into the open end of the spacer and ensure a tight fit. If a reverse flow spacer is used,
insert the valve stem of the pMDI into the port on the mouthpiece of the spacer.
5) Place the mouthpiece of the spacer in the patient’s mouth with the teeth over the mouthpiece and the lips sealed around it.
6) Instruct the individual to exhale slowly, as far as comfortable (to empty their lungs).
7) Actuate one dose into the chamber of the spacer and start to inhale slowly through the mouthpiece. Some spacers will make a whistling noise if inspiration is too fast.
8) Maintain a slow and deep inhalation through the mouth, until the lungs are full of air. This should take a child 2–3
seconds, and an adult 5 seconds.
9) At the end of the inhalation, take the inhaler out of the mouth and close the lips.
10) Continue to hold the breath for as long as possible for up to 10 seconds before breathing out.
11) Breathe normally.
12) If another dose is required, repeat steps 1–11.
13) If inhaled corticosteroids are used, rinse mouth afterwards.

DPIs: for patients ?5 years old (caregiver should determine if child can perform this technique correctly)
1) Take the cap off (some do not have a cap).
2) Follow the dose preparation instructions in the patient information leaflet.
3) Do not point the mouthpiece downwards once a dose has been prepared for inhalation because the dose could fall out.
4) Exhale slowly, as far as comfortable (to empty the lungs). Do not exhale into the DPI.
5) Start to inhale forcefully through the mouth from the very beginning. Do not gradually build up the speed of inhalation.
6) Continue inhaling until the lungs are full.
7) At the end of the inhalation take the inhaler out of the mouth and close the lips. Continue to hold the breath for as long
as possible, or up to 10 seconds.
8) Breathe normally.
9) If another dose is required, repeat steps 1–8.

pMDI=pressurised metered dose inhaler; BA-pMDI=breath-actuated pressurised metered dose inhaler; DPI=dry powder inhaler

Adapted from the European Respiratory Society. Eur Respir J June 2011; 37: 1308–1417; published ahead of print February 10, 2011, doi:10.1183/09031936.00166410. Reproduced with permission

pMDI plus spacers

Spacers were introduced to inhalers to help overcome problems with coordination. A cloud of aerosol is discharged from the pMDI into the spacer, and is then inhaled. After the pMDI is emitted into the spacer the aerosol cloud is stationary and so inhaling from this compared with inhaling a high-velocity spray discharged from a pMDI improves lung deposition,31,32 with greater penetration into the peripheral zones.33 This reduces the impact of the drug in the oro-pharyngeal area and is therefore beneficial. The ERS/ISAM Task Force recommendations on how to use a spacer are shown in Box 1.9

Most spacers are holding chambers and so can be used with tidal (relaxed normal) breathing. Only one dose should be discharged into the spacer—the use of multiple puffs results in a decrease in drug delivery.34 Only 3–5 relaxed breaths should be used when using tidal breathing because the particles will deposit as a result of gravity. If a child is using tidal breathing they should be encouraged to use one full inhalation as soon as they are able to perform this manoeuvre.35

As some spacers are prone to static, they should be washed in water that contains a detergent, and allowed to air dry to reduce the static effect.36 They should not be rinsed with water although instructions for some devices may specify rinsing in this way. It should be noted that spacers are the least preferred portable inhalation method because of their bulk.37

Dry powder inhalers

In recent years, DPIs have been more widely prescribed and used, and many different devices have been introduced. Each type of DPI has its own unique instructions for preparing a dose. Dry powder inhalers have different resistances and so the flows achieved should not be compared; for further details, see Box 2.

Incorrect dose preparation is more than likely to result in no dose being inhaled, irrespective of the inhalation manoeuvre performed by the patient. The ERS/ISAM Task Force has, therefore, emphasised the importance of following the recommended dose preparation instructions provided in the patient information leaflet for each device.9 Once a dose has been prepared, the mouthpiece of a DPI should not be tilted downwards because the dose, which is ready for inhalation, is likely to fall out. Other common errors made by patients using DPIs include:24

  • holding the device in the wrong position or incorrectly
  • actuation at total lung capacity/not exhaling to residual volume before inhaling
  • inadequate or no breath holding after inhalation
  • not using a fast inhalation from the start.

Patients should be trained to perform an inhalation as fast as they can and continue it for as long as possible, as indicated in the ERS/ISAM Task Force instructions in Box 1.9 This will enable them to receive the required lung dose during their inhalation, irrespective of the internal flow resistance of the device. Such inhalations will result in flows that are effective even in devices with a high resistance.47,48

The ERS/ISAM Task Force therefore stresses that the fast inhalation when using a DPI should commence immediately (i.e. at the start of each inhalation). It is important that patients who use an inhalation manoeuvre which starts slowly and gradually increases towards a peak rate should be trained to use a forceful inhalation from the start.

Healthcare professionals should exercise care when prescribing a DPI to young children, and the elderly with chronic obstructive pulmonary disease, as these two groups have reduced inspiratory capacity.38,49


Box 2: Inhalation flow in DPIs

After dose metering (during the dose preparation stage required before each inhalation), the drug particles in a DPI become deaggregated as a result of the turbulent energy generated by the interaction of the patient’s inhalation flow with the resistance inside the inhaler.38 The deaggregated dose leaves the DPI in the first part of an inhalation and the deaggregation process is related to the initial acceleration of the inhalation flow.24,39,40 Different DPIs do not have the same internal resistance to airflow and range from low to high resistance, and each DPI has a threshold below which deaggregation is not efficient.9

When comparing different devices it should be stressed that the inhalation flow only contributes to deaggregation, and that each type of DPI has a different resistance to achieve a set turbulent energy.9 If a DPI has a high resistance then a lower inhalation flow is required compared with a DPI that has a lower resistance. Additionally, higher internal energies are generated when patients use DPIs with a higher resistance because the relationship between the turbulent energy with flow and resistance is not linear.41

The common practice of comparing peak inhalation flow between different devices and suggesting that a DPI is not suitable for a patient because of low inhalation flow is therefore incorrect.38 However, it is valid to compare inhalation flows when using the same device: the higher the inhalation flow, the greater the turbulent energy, thereby leading to better deaggregation of the formulation. All DPIs demonstrate flow-dependent dose emission42 with better lung deposition at higher flows.43,44 It has been suggested that this relates to an improved clinical response, but this is not conclusive.44-46

DPI=dry powder inhaler

Inhalers in real-life settings

The importance of correct inhaler technique, as discussed in this article and highlighted by the ERS/ISAM Task Force, has been reinforced by a recent working party guideline on the primary care management of asthma in real-life settings, which was supported by Teva UK Limited through an educational grant.50 This guideline highlighted that using different devices for controller and reliever therapy may affect control of asthma and that it is therefore good practice for clinicians to prescribe the same inhaler type for both where possible.

When prescribing an inhaler for asthma, healthcare professionals should:50

  • be able to demonstrate appropriate use of inhaler devices to enable them to make a clinically informed decision
  • be aware that cost comparable devices are available, which patients may find easier to use
  • take into account patient factors, such as physical and mental disability, age, and reducing dexterity with advancing age.

The working party group recommended choosing an inhaler that the patient can and will use effectively, and that individuals are involved in the decision-making process. Commissioners of care should ensure that healthcare professionals receive appropriate training in the use of inhaler devices.50

Conclusion

Many patients have problems using the correct inhaler technique. It is therefore important that they are prescribed an inhaler that they can and will use. Patients should comply with their inhaled medication and use the correct method of administration. Each type of inhaler has unique instructions for its use, and patients should be trained accordingly and their technique checked at regular intervals.

Pharmacists should be encouraged to perform medicines reviews and use the New Medicine Service as an opportunity to train patients to adopt the correct inhaler technique, and to check that they have done so.

If a patient is unable to demonstrate good inhaler technique with one device, an alternative inhaler that they can use should be identified.

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