Note
In Check Dial: accuracy for Diskus and Turbuhaler

https://doi.org/10.1016/S0378-5173(02)00650-6Get rights and content

Abstract

Objective: The In Check Dial was developed to evaluate whether a patient is able to generate an adequate peak inspiratory flow (PIF) through a certain inhalation device. The inhalation profile recorder (IPR) is a calibrated instrument that measures flows through Diskus and Turbuhaler in our research setting. The aim of this study was to compare the PIFs of patients when inhaling through a Diskus or Turbuhaler connected with the IPR (PIF_diskus and PIF_TH) to the flows through the corresponding orifices of the In Check Dial (Diskus_In Check and TH_In Check). Methods: Twenty-four stable asthma and twenty-one chronic obstructive pulmonary disease (COPD) patients inhaled, on two separate occasions, in randomised order, via the Diskus or Turbuhaler connected with the IPR. Subsequently, patients inhaled through the In Check Dial using the orifices of Diskus or Turbuhaler. Results: The difference between Diskus_In Check and PIF_diskus was 3.9 (11.9) l/min (P=0.038). The difference between TH_In Check and PIF_TH was 3.5 (10.6) l/min (NS). All Diskus- and Turbuhaler-inhalations were performed with the minimum required flow of 30 l/min. However, four COPD patients inhaled with the non-optimal flow (<60 l/min) through the Turbuhaler. The In Check Dial did not indicate two of them. Conclusion: Measuring PIF through Diskus and Turbuhaler using the IPR and the In Check Dial, respectively shows a disagreement of 3.9 l/min. A disagreement of 3.5 l/min was found for the Turbuhaler. The In Check Dial did not identify two of four patients as ‘non-optimal’ users.

Introduction

Hand-held inhalers such as dry powder inhalers (DPIs) are commonly used for the delivery of drugs into the airways of asthma and chronic obstructive pulmonary disease (COPD) patients.

Multiple factors such as the drug itself, the design of the device (resistivity) and the patient characteristics (Dekhuijzen, 1998, Ganderton, 1997) influence the therapeutic efficacy. Patients have to generate a sufficient inspiratory flow in order to release the powder and to deaggregate the drug into respirable particles. Some patients may be hampered in generating a sufficiently high inspiratory flow, due to pulmonary function, such as hyperinflation, respiratory muscle dysfunction or clinical status (e.g. during an exacerbation) (Madison and Irwin, 1998). Accordingly, some DPIs may be less suitable for certain patients or in certain conditions.

In order to assess such potential absence or loss of efficacy, a new easy to use, hand-held peak inspiratory flow meter, the In-Check Dial (Clement Clarke, UK) was developed. The In Check Dial mimics the internal resistivities of Diskus® (GlaxoSmithKline, UK), Turbuhaler® (AstraZeneca, Sweden), Autohaler® (3 M Pharmaceuticals, USA) and Easi-Breathe® (Norton Healthcare, UK). This meter is intended to evaluate whether an individual patient is able to generate a sufficiently high peak inspiratory flow (PIF) through a certain type of inhalation device.

In the present study, the PIFs of two multidose DPI were compared: Turbuhaler and Diskus. Previous in vitro studies showed that the (higher resistivity) Turbuhaler can produce a therapeutic dose at a PIF of 30 l/min. However, for the Turbuhaler, a maximum fine particle mass and consistent dose delivery is reached at PIF_TH>60 l/min (Borgstrom et al., 1994, Engel et al., 1990, Hill and Slater, 1998). The Turbuhaler reached a higher level in terms of mass median aerodynamic diameter (MMAD) and fine particle mass at 60 l/min as compared to Diskus. So, for this study, PIF_TH>30 l/min is considered ‘minimal’ and PIF_TH>60 l/min as being ‘optimal’. The Diskus has a lower internal resistivity and operates effectively at PIF_diskus>30 l/min (Hill and Slater, 1998, Nielsen et al., 1998). This device provides a consistent fraction of particles <6 μm, relatively independent of airflow (Brindley et al., 1995, Mortensen et al., 1991). For both DPIs, a PIF of 90 l/min is claimed as the maximal flow, because at higher flows the oropharyngeal deposition increases (Borgstrom, 2001).

The inspiratory effort produced by patients, inhaling through a device generates a pressure drop in the mouth. The mouth pressure versus time curve was defined as inhalation profile. The inhalation profiles were stored into the inhalation profile recorder (IPR, GlaxoSmithKline R&D, Ware, UK) (Bisgaard et al., 1998). The pressure profile can be converted into a flow profile when the resistivity of the device is known.

The aim of this study was to compare the PIFs of asthmatics and COPD patients when inhaling through a Diskus or Turbuhaler connected with the IPR (Fig. 1), to the flows when inhaling through the corresponding orifices of the In Check Dial.

Section snippets

Methods and measurements

Twenty-four stable asthma and twenty-one patients with COPD according to ATS (1987) criteria participated in the study. The patient characteristics are shown in Table 1.

They signed a consent form and the hospital ethics committee approved the study.

The study was performed as an open randomised comparison of the PIFs through Diskus and Turbuhaler measured with the IPR (PIF_diskus and PIF_TH) and the flow through the In Check Dial using the orifices of Diskus and Turbuhaler (Diskus_In Check and

Results

The results of the PIF_diskus and PIF_TH and the Diskus_In Check and TH_In Check are shown in Table 2. Fig. 2, Fig. 3 show the differences of PIF_inhalation profile recorder and flows of the In Check Dial for Diskus and Turbuhaler, respectively. The significant difference between Diskus_In Check and PIF_diskus was 3.9 (−19.9 to 27.7) l/min (P=0.038). The difference between TH_In Check and PIF_TH was 3.5 (−17.7 to 24.7) l/min (NS). (Data are expressed as mean±2 S.D.)

The Bland–Altman plots showed

Discussion

Checking the actual PIF may be useful before prescribing DPI, because drug particle release from DPIs is determined by e.g. patient’s effort.

The aim of present study was to assess whether the In Check Dial could be used to predict the PIF through Diskus and Turbuhaler measured with the calibrated IPR.

This study showed mean differences between the values of the In Check Dial and the IPR of 3.9 l/min for the Diskus and 3.5 l/min for the Turbuhaler. This is approximately 3–4% of the PIF value.

The

Acknowledgements

This study is funded by GlaxoSmithKline, Zeist, The Netherlands.

References (14)

There are more references available in the full text version of this article.

Cited by (0)

View full text