Appropriate use of a dry powder inhaler based on inhalation flow pattern
© The Author(s). 2017
Received: 15 October 2016
Accepted: 6 January 2017
Published: 18 January 2017
An optimal inhalation flow pattern is essential for effective use of a dry powder inhaler (DPI). We wondered whether DPI instructors inhale from a DPI with an appropriate pattern, and if not, whether self-training with visual feedback is effective.
Subjects were 14 pharmacists regularly engaged in instruction in DPI use. A newly designed handy inhalation flow visualizer (Visual Trainer: VT) was used to assess inhalation profiles and to assist in self-training. With a peak inhalation flow rate (PIFR) > 50 L/min, time reaching PIFR (TPF) < 0.4 s, inhalation volume (VI) > 1 L, and flow at 0.3 s after the onset of inhalation (F0.3) > 50 L/min, the pattern was considered optimal.
Using Diskus or Turbuhaler 12 and 10 subjects respectively inhaled with a suitable PIFR. Those with a satisfactory F0.3 were 10 and 7 respectively. The TPF was short enough in only 1 and 2 respectively. All 14 subjects inhaled deeply (VI) through Diskus, and 10 did so through Turbuhaler. In the self-training session, only 3 subjects satisfied all three variables at the first trial, while 2 or 3 trials were required in other subjects. Among the three variables, optimal TPF was the most difficult to attain. Once a satisfactory inhalation pattern was achieved using one DPI, eleven out of 12 subjects inhaled with a satisfactory pattern through the other DPI.
Visualization of the inhalation flow pattern facilitates the learning of proper inhalation technique through a DPI.
KeywordsDry powder inhaler Instruction Inhalation flow profile Self-training
Inhalation with an optimal flow pattern is mandatory for effective use of dry powder inhalers (DPIs). The ISAM (International Society of Aerosol in Medicine)/ERS (European Respiratory Society) task force encourages inhalation with different flow patterns using reservoir/blister-type or capsule-type DPIs . However, convenient devices depicting inhaled flow pattern are currently unavailable. Concerning this issue, we previously reported a low-cost and handy inhalation profile analyzer  which displays a trajectory of the inhaled flow through the DPI, and some parameters such as peak inhaled flow rate (PIFR), time reaching the PIFR (TPF), and inhaled volume (VI) are also displayed. Using this device named a Visual Trainer, we found that many patients who were currently treated with a DPI did not inhale with a suitable flow pattern . We then wondered whether DPI instructors themselves inhaled with an ideal inhalation pattern since they also were unaware of their inhalation flow profiles through the DPI. Therefore, as the first purpose of the present study using the Visual Trainer, we assessed DPI inhalation profiles of pharmacists regularly engaged in instruction in DPI use. Pharmacists are largely responsible for DPI instruction in Japan. If they did not inhale with an appropriate flow pattern, as the second purpose, we assessed the effectiveness of visual feedback using the Visual Trainer for self-training.
The second study was conducted 2 weeks later. Only 13 of the 14 pharmacists participated in the study because one subject had already achieved an acceptable inhalation profile. We described the optimal inspiratory flow pattern proposed by the ISAM/ERS task force . Then, without a training session, twelve subjects began self-training for a proper DPI inhalation using Visual Trainers. They repeated inhalations until reaching all the following 3 parameters; PIFR > 50 L/min, TPF < 0.4 s, VI > 1.0 L. We did not direct which DPI device was to be used initially (1st session). In this study 5 visual trainers were distributed among 13 subjects. This enabled the subjects to complete each trial at intermission between their pharmacy duties.
Figure 2b shows the results of 7 consecutive inhalations from Diskus with different flow rates with the time to reach the peak inhalation flow at 0.5 s. The abscissa is output from the penumotachmeter and the ordinate is flow rate calculated from airway pressure, ie, output from the Visual Trainer. There was good correlation between the two outputs, confirming the accuracy of the Visual Trainer.
Inhalation parameters before the self-trainings (median, 75th and 25th percentiles)
77.6, 89.3, 72.2
55.3, 64.5, 47.8
1.63, 2.19, 1.40
1.11, 1.66, 0.95
64.9, 71.6, 58.3
47.2, 52.1, 39.1
0.69, 0.89, 0.57
0.74, 0.93, 0.61
Inhalation therapy using DPIs is now the mainstay of treatment of COPD and bronchial asthma. Since drug dispersion and generation of fine particles are driven by energy from inhaled flow through the DPI, inhalation flow pattern including flow rate and timing of peak flow impact its efficiency. Once dispersed from the DPI, powdered drugs are propelled through the airways and then precipitate in the large and small bronchi making strength and depth of inhalation important. However, compared with instruction in employing a DPI, systematic instruction in inhalation flow through a DPI is not widely practiced. One reason may be poor recognition of DPI-specific inhalation patterns  by many DPI instructors, and this may be partly due to lack of a convenient device to visualize inhalation flow pattern. In-check and inhalation trainers currently used are not satisfactory for this purpose because these devices depict inhalation flow rate at only one point in time. A few systems visualizing the time course of inhalation flow rate from a DPI have been reported [4–6]. However, all of these systems are either complicated or expensive, and thus are not suited to use in clinical practice. Visual trainer, a low-cost and handy inhalation profile analyzer, potentially solves these problems.
Concerning the threshold value, we used a PIFR > 50 L/min because this value is recommended in use of medium/high-resistance DPIs . According to one study on children well trained in DPI use , in which the peak of drug dispersion from Diskus was 0.16 ± 0.14 s (mean ± SD) and that from Turbuhaler was 0.19 ± 0.03 s, the PIFR should appear at around 0.16–0.19 s after onset of inhalation. In our previous study using the inhalation trainers in healthy adults, the TPF through Diskus was 0.44 ± 0.17 s and that through Turbuhaler was 0.53 ± 0.23 s . Thus, we set the requirement of TPF as < 0.4 s. Although the optimal VI from a DPI is not established, 80% vital capacity is recommended in pMDI (pressurized metered dose inhaler) use. However, favorable pulmonary drug deposition (comparisons of 20, 50 and 80% vital capacities)  or drug absorption (functional residual volume vs. total lung capacity)  was reported with smaller inhalation volume. We set 1.0 L as a minimum requirement for VI. Inhaled flows at 0.3 s after onset of inhalation (F0.3), which represents the flow rate at termination of drug dispersion , was also measured.
The ISAM/ERS task force recommends a rapid and forceful inhalation for reservoir or blister-type DPI . Once drug has been dispersed from a DPI, inhalation flow rate should be low to avoid precipitation in the upper airway. Studies on pMDI's suggest that a suitable flow after drug dispersion is approximately 30 L/min . Thus, practically the best inhalation pattern for Diskus and Turbuhaler may be that shown as Fig. 4a , and this pattern is exactly the same as that proposed by the ISAM/ERS task force.
Pharmacists’ inhaled pattern
As shown in Figs. 5a and d, most of the pharmacists inhaled forcefully (high PIFR) and deeply (large VI) through both DPIs. The steepness of inhaled flow was assessed by two parameters, TPF and F0.3. Most of the subjects inhaled with an unsatisfactory TPF through either DPI (Fig. 5c). Although TPF is a reasonable parameter of flow steepness it is not a suitable index in evaluation of the trapezoid pattern (see Fig. 4). Since the trapezoid pattern was frequently seen in this study, we adopted F0.3 as an additional parameter of flow steepness. A satisfactory F0.3 was observed in 12 of 14 subjects in Diskus use but in only half of the subjects with Turbuhaler use (Fig. 5b). Even though high F0.3 is achieved, the trapezoid pattern is not preferable because protracted high inhaled flow may adversely affect both drug delivery and precipitation in the pulmonary airways. Therefore, we concluded that our subjects, who are regularly engaged in DPI inhalation instruction, did not themselves inhale with an appropriate flow pattern.
Effects of training with visual feedback
Steep increase in inhalation flow has a marked effect on drug dispersion  as well as fine particle generation from a DPI . Unfortunately, many of our subjects failed to achieve sufficiently rapid inhalation in terms of TPF and F0.3. This finding is not surprising because currently available devices such as In-Check or trainer whistles do not show flow trajectory. Al-Showair et al.  have reported that an optimal inhalational flow pattern was not achieved following verbal instruction, and we also confirmed this . Furthermore, even after describing an optimal flow pattern, only 20% of the subjects in the present study achieved a satisfactory pattern at the first trial. Thus, currently available techniques including verbal instructions, flow trainer devices, and description of optimal flow are limited. In contrast, after self-training with Visual Trainer TPFs decreased remarkably. Since drug dispersion occurs at very early inhalation, early development of PIFR augments inhalation efficiency. As has been reported, some maneuvers augment inhalation depth and strength  but no strategy for achieving rapid inhalation has been proposed. Although our study had no control group, the results suggest that self-training with visual feedback is a strong tool to resolve this problem.
Once a subject had achieved an optimal flow pattern using one DPI, many subjects inhaled optimally through the other DPI (Fig. 6a). This occurred whether the DPIs were changed from those with medium/high to low resistance or vice versa. This suggests that, when the type of DPI is changed, detailed instruction in flow pattern is not required in well-trained patients.
Usefulness of visual trainer
With regard to the Visual Trainer in this study, we were able to use 5 devices concurrently in the 2nd trial owing to their cheap and handy attributes. This enabled the collection of data in only one day while all the pharmacists were engaged in their hospital duties. Short-term data collection might also preclude information exchange among the subjects who, in the self- training study, could have impacted the results. We have reported that patients regularly using DPIs do not always inhale with adequate flow patterns .The present results portend the effectiveness of Visual Trainer in training such patients.
Visualization of the inhalation flow pattern facilitates the learning of proper inhalation technique through a DPI. An optimal inhalation pattern can be easily achieved by self-training when the inhalation flow pattern is displayed.
Chronic obstructive pulmonary disease
Dry powder inhaler
European respiratory society
- F0.3 :
Inhaled flows at 0.3 s after onset of inhalation
Graphic liquid cell display
International society of aerosol in medicine
- Paw :
Pressure in the mouthpiece of a DPI
Peak inhaled flow rate
Pressurized metered dose inhaler
- TPF :
Time to reach the PIFR
- VI :
There was no funding for this research.
Availability of data and materials
Please contact author for data requests.
TK, TT, and ST conceived and designed the study. SMC and KA supervised the research process. TK and MH performed the data collection. TK, TT, and SMC drafted the manuscript. All authors analyzed and interpreted the data. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
All the subjects participated voluntarily in the study after signing an informed consent. It was written in the consent form that statistically processed data from the participant will be opened.
Ethics approval and consent to participate
This study was permitted by the Human Ethics Committee of Shonan Fujisawa Tokushukai Hospital (approval number 14–019).
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Laube BL, Janssens HM, de Jongh FHC, Devadason SG, Dhand R, Diot P, et al. What the pulmonary specialists should know about new inhalation therapies. Eur Respir J. 2011;37:1308–31.View ArticlePubMedGoogle Scholar
- Kondo T, Hibino M, Tanigaki T, Kato S, Ohe M, Akazawa K. Inhalation flow patterns from a dry powder inhaler in patients with bronchial asthma: usefulness of a newly-designed handy inhalation profile analyzer. Jpn J Pharmaceut Health Care Sci. 2015;41:388–93.View ArticleGoogle Scholar
- Kondo T, Tanigaki T, Tajiri S, Ohe M, Hibino M, Akazawa K. Profiles of inhaled flow from dry powder inhalers in subjects unfamiliar with the device. Jpn J Pharmaceut Health Care Sci. 2014;40:344–51.View ArticleGoogle Scholar
- Cegla UH. Pressure and inspiratory flow characteristics of dry powder inhalers. Respir Med. 2004;98(suppl A):S22–8.View ArticlePubMedGoogle Scholar
- Broeders MEAC, Molema J, Hop WCJ, Vermue NA, Folgering HTM. The course of inhalation profiles during an exacerbation of obstructive lung disease. Respir Med. 2004;98:1173–9.View ArticlePubMedGoogle Scholar
- Kamin WES, Genz T, Roeder S, Scheuch G, Cloes R, Juenemann R, Trammer T. The inhalation manager: A new computer-based device to assess inhalation technique and drug delivery to the patient. J Aerosol Med. 2003;16:21–9.View ArticlePubMedGoogle Scholar
- Bisgaard H, Klug B, Sumby BS, Burnell PK. Fine particle mass from Diskus inhaler and Turbuhaler inhaler in children with asthma. Eur Respir J. 1998;11:1111–5.View ArticlePubMedGoogle Scholar
- Kondo T, Tanigaki T, Hibino M, Ohe M, Kato S. Resistances of dry powder inhalers and training whistles and their clinical significance. Jpn J Allergol. 2014;63:1325–9.Google Scholar
- Newman SP, Pavia D, Garland N, Clarke SW. Effects of various inhalation modes on the deposition of radioactive pressurized aerosols. Eur J Respir Dis. 1982;119(suppl):57–65.Google Scholar
- Hindle M, Newton DAG, Chrystyn H. Investigations of an optimal inhaler technique with the use of urinary salbutamol excretion as a measure of relative bioavailability to the lung. Thorax. 1993;48:607–10.View ArticlePubMedPubMed CentralGoogle Scholar
- Gemünden A. Novel approaches to enhance pulmonary delivery of proteins and peptides. J Physiol Pharmacol. 2007;58 suppl 5:615–25.Google Scholar
- Chavan V, Dalby R. Effect of rise in simulated inspiratory flow rate and carrier particle size on powder emptying from dry powder inhaler. AAPS Pharmasci. 2000;2:1–7.View ArticleGoogle Scholar
- Everard ML, Devadason SG, Souef PN. Flow early in the inspiratory manoeuvre affects the aerosol particle size distribution from a Turbuhaler. Respir Med. 1997;91:624–8.View ArticlePubMedGoogle Scholar
- Al-Showair RAM, Tarsin WY, Assi KH, Pearson SB, Chrystyn H. Can all patients with COPD use the correct inhalation flow with all inhalers and does training help? Respir Med. 2007;101:2395–401.View ArticlePubMedGoogle Scholar
- Kondo T, Hibino M, Tanigaki T, Ohe M, Kato S. Exhalation immediately before inhalation optimizes dry powder inhaler use. J Asthma. 2015;52:935–9.View ArticlePubMedGoogle Scholar