The Impact of Inspiratory Muscle Function on Inhaler Device Adaptability in Stable COPD Patients.

Abstract

Objective: This study investigated the relationship between inspiratory muscle function and inhaler device adaptability in stable chronic obstructive pulmonary disease (COPD) patients, addressing the gaps in objective evaluation methods for inhaler device effectiveness in clinical practice.

Methods: A cross-sectional study of 701 stable COPD patients (498 males, 203 females; aged 48-83 years) from the First People's Hospital of Xiaoshan District was conducted from June 2023 to May 2024. Maximum inspiratory pressure (MIP) measured respiratory muscle function, while average effective inspiratory flow assessed inhaler adaptability. Participants used either dry powder inhalers (DPI) or pressurized metered-dose inhalers/soft mist inhalers (pMDI/SMI). Multiple regression models adjusted for demographic and respiratory parameters.

Results: Higher MIP quartiles correlated with increased average effective inspiratory flow (Q4 vs. Q1: β = 8.1 L/min, 95% CI: 5.1-11.0, p < 0.001) after adjusting for demographic factors. This association diminished after controlling for respiratory parameters, suggesting MIP indirectly affects inhaler adaptability through intermediate respiratory metrics. A potential threshold effect was identified at MIP of 23.1 cmH₂O, though not statistically significant (p = 0.208).

Conclusion: Our study demonstrates that inspiratory muscle function, as assessed by MIP, is significantly associated with measures of inhaler device adaptability, and identifies a physiologically relevant threshold range that may help characterize patient requirements for inhalers of differing resistance.