Abstract
<b><i>Background:</i></b> Dry powder inhaler (DPI) use requires sufficient peak inspiratory flow over the DPI internal resistance (PIF<sub>R</sub>). <b><i>Objectives:</i></b> We examined whether spirometric peak inspiratory flow (PIF<sub>spiro</sub>) could serve to predict PIF<sub>R</sub> in patients with obstructive lung disease. <b><i>Method:</i></b> Thirty healthy nonsmokers and 140 stable outpatients (70 COPD, 70 asthma) performed spirometry according to the 2019 ERS/ATS spirometry update, yielding PIF<sub>spiro</sub>. Using a PIF<sub>R</sub> measurement device with varying orifices, all subjects’ PIF<sub>R</sub> values were recorded for 5 predefined resistance levels, characterized by 5 orifice cross sections (S<sub>R</sub>). A test group including all healthy subjects, 30 of the asthma, and 30 of the COPD patients was used to establish the relationship between PIF<sub>R</sub> and both PIF<sub>spiro</sub> and S<sub>R</sub> by multiple regression. A validation group including the remaining 40 asthma and 40 COPD patients, served to verify whether their predicted PIF<sub>R</sub> value corresponded to the measured PIF<sub>R</sub> for each resistance level. <b><i>Results:</i></b> The asthma (FEV<sub>1</sub> = 78 ± 17 [SD] %pred) and COPD (FEV<sub>1</sub> = 46 ± 17 [SD] %pred) patients under study had varying airway obstruction. In the test group, PIF<sub>R</sub> could be predicted by ln[PIF<sub>spiro</sub>] (<i>p</i> < 0.0001), S<sub>R</sub> (<i>p</i> < 0.0001), and S<sub>R</sub><sup>2</sup> (<i>p</i> = 0.006), with an adjusted <i>R</i><sup>2</sup> = 0.71. In the validation group, estimated PIF<sub>R</sub> did not significantly differ from measured PIF<sub>R</sub> (<i>p</i> > 0.05 for the 5 resistance levels). <b><i>Conclusions:</i></b> We propose a simple method to predict PIF<sub>R</sub> for a range of common DPI resistances, based on the device characteristics and on the patient’s characteristics reflected in PIF<sub>spiro</sub>. As such, routine spirometry can serve to estimate a patient’s specific PIF<sub>R</sub> without the need for additional testing.
Subject
Pulmonary and Respiratory Medicine
Cited by
1 articles.
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