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      Prevalence and factors associated with suboptimal peak inspiratory flow rates in COPD

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          Adequate peak inspiratory flow rate (PIFR) is required for drug dispersion with dry powder inhalers (DPIs). Prevalence of PIFR discordance (suboptimal PIFR with prescribed inhalers) and factors influencing device-specific PIFR are unclear in COPD. The objective of this study was to determine the prevalence of PIFR discordance and associated clinical factors in a stable COPD population.

          Patients and methods

          An observational, single-center, cohort study was conducted including 66 outpatients with COPD. PIFR was measured using the In-Check™ Dial with applied resistance of prescribed inhalers. Participants were defined as discordant if measured PIFR was <30 L/min and <60 L/min for high and low–medium resistance devices, respectively, using an inspiratory effort the participant normally used with their prescribed DPI.


          The median age of the COPD participants was 69.4 years, 92% were white and 47% were female. A total of 48% were using low–medium resistance DPIs (Diskus ®/Ellipta ®) and 76% used high-resistance DPI (Handihaler ®). A total of 40% of COPD participants were discordant to prescribed inhalers. Female gender was the only factor consistently associated with lower PIFR. Shorter height was associated with reduced PIFR for low–medium resistance ( r=0.44; P=0.01), but not high resistance ( r=0.20; P=0.16). There was no correlation between PIFR by In-Check™ dial and PIFR measured by standard spirometer.


          PIFR is reduced in stable COPD patients, with female gender being the only factor consistently associated with reduced PIFR. Discordance with prescribed inhalers was seen in 40% of COPD patients, suggesting that many COPD patients do not generate adequate inspiratory force to overcome prescribed DPIs resistance in the course of normal use.

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          Most cited references 22

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          Deposition of corticosteroid aerosol in the human lung by Respimat Soft Mist inhaler compared to deposition by metered dose inhaler or by Turbuhaler dry powder inhaler.

          Fourteen mild-to-moderate asthmatic patients completed a randomized four-way crossover scintigraphic study to determine the lung deposition of 200 microg budesonide inhaled from a Respimat Soft Mist Inhaler (Respimat SMI), 200 microg budesonide inhaled from a Turbuhaler dry powder inhaler (Turbuhaler DPI, used with fast and slow peak inhaled flow rates), and 250 microg beclomethasone dipropionate inhaled from a pressurized metered dose inhaler (Becloforte pMDI). Mean (range) whole lung deposition of drug from the Respimat SMI (51.6 [46-57]% of the metered dose) was significantly (p < 0.001) greater than that from the Turbuhaler DPI used with both fast and slow inhaled flow rates (28.5 [24-33]% and 17.8 [14-22]%, respectively) or from the Becloforte pMDI (8.9 [6-12]%). The deposition pattern within the lungs was more peripheral for Respimat SMI than for Turbuhaler DPI. The results of this study showed that Respimat SMI deposited corticosteroid more efficiently in the lungs than either of two widely used inhaler devices, Turbuhaler DPI or Becloforte pMDI.
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            Prevalence and COPD phenotype for a suboptimal peak inspiratory flow rate against the simulated resistance of the Diskus® dry powder inhaler.

            Patients who exhibit a suboptimal peak inspiratory flow rate (PIFR) against the resistance (resist) of a dry powder inhaler (DPI) may not be able to effectively inhale the medication into their lower respiratory tract. PIFRresist was measured using the In-Check DIAL(®) to simulate the resistance of the Diskus(®) DPI in patients with chronic obstructive pulmonary disease (COPD) who were ≥ 60 years of age and had forced expiratory volume in 1 sec (FEV1) of ≤ 50% predicted. Our objectives were to: establish the prevalence of a suboptimal PIFRresist (< 60 L/min) in this population; identify a phenotype of patients with COPD who exhibit a suboptimal PIFRresist; and assess test-retest reliability of PIFRresist.
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              The relationship between powder inhaler resistance and peak inspiratory conditions in healthy volunteers--implications for in vitro testing.

              Despite the fact that powder inhaler devices have been available for over 3 decades there is still very little fundamental information as to how powder inhaler design interacts with the airway dynamics of patients. This paper documents the results of human volunteer investigations designed to elucidate this interaction. These data indicates that if 'maximum' inhalation effort is employed the flow rate attained through an inhaler is controlled by the maximum pressure drop developed by the chest muscles. If a moderate or 'comfortable' effort is used, however, the relationship is more complex. An equation for defining the 'respirable fraction' of an inhalation aerosol cloud as a function of inhalation flow rate is also proposed.

                Author and article information

                Int J Chron Obstruct Pulmon Dis
                Int J Chron Obstruct Pulmon Dis
                International Journal of COPD
                International Journal of Chronic Obstructive Pulmonary Disease
                Dove Medical Press
                01 March 2019
                : 14
                : 585-595
                [1 ]Division of Pulmonary Diseases and Critical Medicine, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA, brad_drummond@
                [2 ]Durham VA Medical Center, Durham, NC, USA
                [3 ]Department of Medicine, Section of Pulmonary, Critical Care, Allergy, and Immunology, School of Medicine, Wake Forest University, Winston-Salem, NC, USA
                Author notes
                Correspondence: M Bradley Drummond, Division of Pulmonary Diseases and Critical Medicine, Department of Medicine, University of North Carolina at Chapel Hill, Marsico Hall Room 7207, CB# 7248, 125 Mason Farm Road, Chapel Hill, NC 27599, USA, Tel +1 919 966 7054, Fax +1 919 966 5178, Email brad_drummond@
                © 2019 Ghosh et al. This work is published and licensed by Dove Medical Press Limited

                The full terms of this license are available at and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

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