Annals of Biomedical Engineering

, Volume 47, Issue 4, pp 990–999 | Cite as

EIT Imaging of Upper Airway to Estimate Its Size and Shape Changes During Obstructive Sleep Apnea

  • Ghazal Ayoub
  • Young Eun Kim
  • Tong In Oh
  • Sang-Wook Kim
  • Eung Je WooEmail author


Noninvasive continuous imaging of the upper airway during natural sleep was conducted for patients with obstructive sleep apnea (OSA) using the electrical impedance tomography (EIT) technique. A safe amount of alternating current (AC) was injected into the lower head through multiple surface electrodes. Since the air is an electrical insulator, upper airway narrowing during OSA altered internal current pathways and changed the induced voltage distribution. Since the measured voltage data from the surface of the lower head were influenced not only by upper airway narrowing but respiratory motions, head motions, and blood flows, we developed a pre-processing algorithm to extract the voltage component originated from upper airway closing and opening. Using an EIT image reconstruction algorithm, time-series of EIT images of the upper airway were produced with a temporal resolution of 50 frames per second. Applying a postprocessing algorithm to the reconstructed EIT images, we could extract quantitative information about changes in the size and shape during upper airway closing and opening. Results of the clinical studies with seven normal subjects and ten OSA patients show the feasibility of the new method for OSA phenotyping and treatment planning.


Obstructive sleep apnea (OSA) Upper airway Electrical impedance tomography (EIT) Upper airway size Upper airway shape 



This work was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (Grant Number: HI17C0984) and the National Research Foundation (NRF-2017R1A2B2002169) in Republic of Korea.


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Copyright information

© Biomedical Engineering Society 2019

Authors and Affiliations

  1. 1.Department of Biomedical Engineering, Graduate SchoolKyung Hee UniversityYonginRepublic of Korea
  2. 2.Department of Medical Engineering, Graduate SchoolKyung Hee UniversitySeoulRepublic of Korea
  3. 3.Department of OtorhinolaryngologyGyeongsang National University College of Medicine and Gyeongsang National University HospitalJinjuRepublic of Korea
  4. 4.BiLabSeoulRepublic of Korea
  5. 5.Department of Biomedical Engineering, College of MedicineKyung Hee UniversitySeoulRepublic of Korea

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