AUTHOR=Piccin Vivien S. , de Camargo Erick D. L. B. , Andrade Rafaela G. S. , Torsani Vinícius , Schorr Fabíola , Sardinha Priscilla S. , Madeiro Fernanda , Genta Pedro R. , Gregório Marcelo G. , de Carvalho Carlos R. R. , Amato Marcelo B. P. , Lorenzi-Filho Geraldo 

TITLE=Feasibility of neck electrical impedance tomography to monitor upper airway dynamics during sleep

JOURNAL=Frontiers in Sleep

VOLUME=2

YEAR=2023

URL=https://www.frontiersin.org/journals/sleep/articles/10.3389/frsle.2023.1238508

DOI=10.3389/frsle.2023.1238508

ISSN=2813-2890

ABSTRACT=<sec><title>Background</title><p>There is a lack of non-invasive methods for monitoring the upper airway patency during sleep. Electrical impedance tomography (EIT) is a non-invasive, radiation-free tool that has been validated to monitor lung ventilation. We hypothesized that electrical impedance tomography (EIT) can be used for monitoring upper airway patency during sleep.</p></sec><sec><title>Methods</title><p>Sleep was induced in 21 subjects (14 males, age 43 ± 13 years, body mass index 32.0 ± 5.3 kg/m<sup>2</sup>) with suspected obstructive sleep apnea (apnea-hypopnea index: 44 ± 37 events/h, range: 1–122 events/h) using low doses of midazolam. Patients wore a nasal mask attached to a modified CPAP device, allowing variable and controlled degrees of upper airway obstruction. Confirmation of upper airway patency was obtained with direct visualization of the upper airway using nasofibroscopy (<italic>n</italic> = 6). The changes in total neck impedance and in impedance in four cranio-caudal regions of interest (ROIs) were analyzed.</p></sec><sec><title>Results</title><p>Total neck impedance varied in concert with breathing cycles and peaked during expiration in all patients. Group data showed a high cross-correlation between flow and impedance curves (<italic>r</italic> = −0.817, <italic>p</italic> &lt; 0.001). Inspiratory peak flow correlated with simultaneous neck impedance (<italic>r</italic> = 0.866, <italic>p</italic> &lt; 0.001). There was a high correlation between total neck impedance and velopharynx area (<italic>r</italic> = 0.884, <italic>p</italic> &lt; 0.001), and total neck impedance and oropharynx area (<italic>r</italic> = 0.891, <italic>p</italic> &lt; 0.001).</p></sec><sec><title>Conclusions</title><p>Neck EIT is sensitive and captures pharyngeal obstruction under various conditions. Neck EIT is a promising method for real-time monitoring of the pharynx during sleep.</p></sec>