Objective Assessment of Patient Inhaler User Technique Using an Audio-Based Classification Approach

Area of Science:

• Respiratory medicine
• Biomedical engineering
• Medical device technology

Background:

• Pressurized metered dose inhalers (pMDIs) are crucial for respiratory medication delivery.
• Critical user technique errors, such as poor actuation coordination and rapid inhalation, significantly reduce pMDI clinical efficacy.
• Current methods for assessing inhaler technique are often subjective and lack precision.

Purpose of the Study:

• To introduce and validate a novel audio-based method for objectively assessing patient technique when using pMDIs.
• To evaluate the accuracy of this audio-based method in classifying inhaler use events and estimating key physiological parameters.
• To determine the prevalence of critical user technique errors among respiratory patients using pMDIs.

Main Methods:

• An audio-based assessment method using the Inhaler Compliance Assessment device was developed.
• Audio signals were recorded from 62 respiratory patients using a pMDI with an attached In-Check Flo-Tone device.
• Quadratic discriminant analysis was applied to classify sound events and estimate peak inspiratory flow rate and inhalation volume.

Main Results:

• The audio-based method achieved 88.2% frame-by-frame accuracy in classifying actuation, inhalation, and exhalation events.
• Peak inspiratory flow rate and inhalation volume were estimated with accuracies of 88.2% and 83.94%, respectively.
• Despite expert tuition, 89% of patients exhibited at least one critical user technique error.

Conclusions:

• The novel audio-based method provides an objective and clinically accurate assessment of pMDI user technique.
• This technology offers a significant improvement over traditional checklist-based assessment methods.
• The high prevalence of errors highlights the need for improved patient education and monitoring of inhaler technique.