Prevalence and factors associated with suboptimal peak inspiratory flow rates in COPD
Received 21 November 2018
Accepted for publication 31 January 2019
Published 1 March 2019 Volume 2019:14 Pages 585—595
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 2
Editor who approved publication: Dr Richard Russell
Sohini Ghosh,1 Roy A Pleasants,2 Jill A Ohar,3 James F Donohue,1 M Bradley Drummond1
1Division of Pulmonary Diseases and Critical Medicine, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; 2Durham VA Medical Center, Durham, NC, USA; 3Department of Medicine, Section of Pulmonary, Critical Care, Allergy, and Immunology, School of Medicine, Wake Forest University, Winston-Salem, NC, USA
Purpose: 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.
Results: 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.
Conclusion: 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.
Keywords: pulmonary disease, chronic obstructive, dry powder inhaler, peak inspiratory flow rate, drug delivery systems
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