ADVERTISEMENT

Issue Navigator

Volume 15 No. 04
Earn CME
Accepted Papers





Scientific Investigations

Real-Time Identification of Upper Airway Occlusion Using Electrical Impedance Tomography

Young Eun Kim, MS1; Eung Je Woo, PhD1; Tong In Oh, PhD1; Sang-Wook Kim, MD, PhD2,3
1Department of Medical Engineering, Graduate School, Kyung Hee University, Seoul, Republic of Korea; 2Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea; 3Department of Otorhinolaryngology, Gyeongsang National University College of Medicine and Gyeongsang National University Hospital, Jinju, Republic of Korea

Study Objectives:

Real-time monitoring of upper airway collapse during sleep could be instrumental for studies in biomechanics of obstructive sleep apnea (OSA) and selecting individualized treatment modalities. Although some imaging techniques are used under sedated sleep, none are available during the entire natural sleep process. We hypothesized that electrical impedance tomography (EIT) can be used for noninvasive continuous imaging of the upper airway during natural sleep and quantifying upper airway collapse in terms of its size.

Methods:

After determining surface landmarks to attach the electrodes for monitoring the retroglossal airway, EIT was conducted in 10 healthy participants. As a feasibility test of EIT in detecting upper airway collapse, transient airway closure was induced by the swallowing maneuver. These EIT images were confirmed by simultaneous magnetic resonance imaging (MRI) scans. Subsequently, EIT scans were conducted in 7 healthy participants and 10 patients with OSA under nonsedated sleep to determine whether it could identify upper airway narrowing or collapse. Respiratory events were identified by concurrent polysomnography (PSG).

Results:

Swallowing-induced airway closure was identified successfully in all 10 participants on simultaneous EIT and MRI scans. Sizes and positions of the upper airway closures in reconstructed EIT images were well correlated with those in magnetic resonance images. Obstructive hypopnea and apnea were detected successfully by EIT in 10 patients with OSA, and no significant changes in EIT data were observed in 7 healthy participants during concurrent EIT and PSG tests. Additionally, conductivity changes in the airway were greater during obstructive apnea than during hypopnea (64.3% versus 26.3%, respectively; P < .001) compared with those during baseline respiration.

Conclusions:

EIT could be a useful real-time monitoring device for detecting upper airway narrowing or collapse during natural sleep in patients with OSA. Currently, changes in the upper airway size can be estimated with good accuracy, but shape estimation needs future improvements in the EIT image quality.

Citation:

Kim YE, Woo EJ, Oh TI, Kim SW. Real-time identification of upper airway occlusion using electrical impedance tomography. J Clin Sleep Med. 2019;15(4):563–571.


Supplemental Material

Login to view supplemental material



Please login to continue reading the full article

Subscribers to JCSM get full access to current and past issues of the JCSM.

Login to JCSM

Not a subscriber?

Join the American Academy of Sleep Medicine and receive a subscription to JCSM with your membership

Subscribe to JCSM:  $125/volume year for individuals or $225/volume year for institutions to access all current articles and archives published in JCSM.

Download this article*:   $20 to access a PDF version of a specific article from the current issue of JCSM.

*Purchase of an article provides permission to access and print the article for personal scholarly, research and educational use. Please note: access to the article is from the computer on which the article is purchased ONLY. Purchase of the article does not permit distribution, electronic or otherwise, of the article without the written permission of the AASM. Further, purchase does not permit the posting of article text on an online forum or website.