Optical coherence tomography to identify upper airway obstruction sites in an apneic patient

There are important limitations to the current diagnostic tools for obstructive sleep apnea (OSA).

The limitations warrant the development of a more accurate, minimally invasive, and objective tool to better characterize upper airway airflow obstruction during sleep.

Swept-source optical coherence tomography (OCT) as a range-finding technique was utilized for upper airway volumetric reconstruction. An acousto-optic modulator was integrated into the OCT system for extending the imaging range to be suitable for the typical diameter of the upper airway. High spatial resolution images were acquired at $25\text{frames}/s$ and translated at $12.5\mathrm{mm}/s$ before manual segmentation for three-dimensional (3D) reconstruction and numerical analysis. The Lattice-Boltzmann method as a computational fluid dynamics (CFD) technique was utilized to pinpoint the precise locations of turbulent airflow in the airspace.

Upper airway OCT imaging of a 28-year-old individual with sleep disorder breathing was obtained during awake and sleep periods. The volumetric structure and 3D reconstruction of the upper airway through a micrometer-resolution optical imaging approach were successfully demonstrated. Cross-sectional volumetric changes from awake to sleep periods were calculated, and the greatest airway obstruction was observed at the level of the oropharynx. In addition to CFD analysis, measuring airflow pressure differences along the upper airway aided in accurately localizing the dominant sites of obstruction during sleep.

The combination of the proposed OCT imaging system with 3D remodeling and CFD analysis led to accurate reconstruction of the upper airway and identification of obstruction sites during sleep. This technology can improve surgical decision-making and outcomes in OSA.