Acoustic reflectometry for airway measurements in man: implementation and validation

Area of Science:

• Medical Imaging
• Respiratory Physiology
• Biomedical Engineering

Background:

• Accurate measurement of airway dimensions is crucial for diagnosing and managing respiratory conditions.
• Previous acoustic reflectometry systems were limited by bulkiness, required specific breathing maneuvers, and lacked real-time feedback.

Purpose of the Study:

• To describe a practical, portable acoustic reflectometry system for routine clinical airway area determination.
• To validate the accuracy and reproducibility of the new system.
• To compare acoustic measurements with magnetic resonance imaging (MRI) in human volunteers.

Main Methods:

• Development and implementation of a portable acoustic reflectometry device allowing measurements during free breathing.
• Validation using an airway model to assess accuracy and reproducibility (coefficient of variation, CV).
• Comparison of acoustic and MRI measurements of pharyngeal and glottal areas in ten healthy volunteers.

Main Results:

• The acoustic reflectometer demonstrated 5-10% accuracy and reproducibility with an airway model.
• Human volunteer studies showed within-run CV of ~10% and day-to-day CV of ~20%.
• Acoustic and MRI measurements of oropharyngeal (1.0 vs. 0.9 cm²) and glottal areas (1.3 vs. 1.1 cm²) showed no significant differences (p=0.77 and p=0.09, respectively).

Conclusions:

• The developed portable acoustic reflectometry system is a viable tool for routine clinical assessment of airway areas.
• The system offers advantages of portability, free breathing measurements, and real-time display.
• Acoustic reflectometry provides comparable results to MRI for pharyngeal and glottal area assessment.