The korean journal of orthodontics (대한치과교정학회지)

The Korean Association Of Orthodontists (대한치과교정학회)
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Morphological characteristics of the upper airway and pressure drop analysis using 3D CFD in OSA patients

폐쇄성 수면무호흡 환자의 상기도 형태의 특징과 압력강하에 관한 3차원 전산유체역학해석

  • Mo, Sung-Seo (Division of Orthodontics, Department of Dentistry, College of Medicine, The Catholic University of Korea, St. Mary's Hospital) ;
  • Ahn, Hyung-Taek (School of Naval Architecture & Ocean Engineering, University of Ulsan) ;
  • Lee, Jeong-Seon (Department of Medicine Orthodontics, The Graduate School of the University of Ulsan) ;
  • Chung, Yoo-Sam (Department of Otolaryngology, University of Ulsan College of Medicine, Asan Medical Center) ;
  • Moon, Yoon-Shik (Department of Orthodontics, University of Ulsan College of Medicine, Asan Medical Center) ;
  • Pae, Eung-Kwon (Section of Orthodontics in the Division of Associated Clinical Specialties at the UCLA School of Dentistry) ;
  • Sung, Sang-Jin (Department of Orthodontics, University of Ulsan College of Medicine, Asan Medical Center)
  • 모성서 (가톨릭대학교 의과대학 성모병원 교정과) ;
  • 안형택 (울산대학교 공과대학 조선해양공학부) ;
  • 이정선 (울산대학교 대학원 의학과 교정학) ;
  • 정유삼 (울산대학교 의과대학 서울아산병원 이비인후과) ;
  • 문윤식 (울산대학교 의과대학 서울아산병원 교정과) ;
  • 배응권 (UCLA 치과대학 교정과) ;
  • 성상진 (울산대학교 의과대학 서울아산병원 교정과)
  • Received : 2009.10.07
  • Accepted : 2010.03.03
  • Published : 2010.04.30
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Abstract

Objective: Obstructive sleep apnea (OSA) is a common disorder which is characterized by a recurrence of entire or partial collapse of the pharyngeal airway during sleep. A given tidal volume must traverse the soft tissue tube structure of the upper airway, so the tendency for airway obstruction is influenced by the geometries of the duct and characteristics of the airflow in respect to fluid dynamics. Methods: Individualized 3D FEA models were reconstructed from pretreatment computerized tomogram images of three patients with obstructive sleep apnea. 3D computational fluid dynamics analysis was used to observe the effect of airway geometry on the flow velocity, negative pressure and pressure drop in the upper airway at an inspiration flow rate of 170, 200, and 230 ml/s per nostril. Results: In all 3 models, large airflow velocity and negative pressure were observed around the section of minimum area (SMA), the region which narrows around the velopharynx and oropharynx. The bigger the Out-A (outlet area)/ SMA-A (SMA area) ratio, the greater was the change in airflow velocity and negative pressure. Conclusions: Pressure drop meaning the difference between highest pressure at nostril and lowest pressure at SMA, is a good indicator for upper airway resistance which increased more as the airflow volume was increased.

폐쇄성 수면무호흡(obstructive sleep apnea, OSA)은 수면 중에 반복적으로 상기도의 완전폐쇄나 부분폐쇄가 일어나는 질환으로서 흡기된 공기는 반드시 상기도라는 연조직 관(tube) 구조를 통과해야 하므로 상기도의 폐쇄경향은 관의 형태 및 관을 통과하는 공기의 유체역학적 특성에 따라서도 큰 영향을 받을 수 있다. 본 연구에서는 OSA 환자 3인의 치료 전 상기도 CT 이미지를 이용하여 개별화된 3차원 유한요소모델 A, B, C를 제작하고, 비공 당 170, 200, 230 ml/s의 흡기유량에 대하여 3차원 전산유체역학 해석을 시행하였다. 상기도의 유속, 음압 그리고 압력강하를 측정한 결과 관찰된 3개의 모델에서 모두 단면적이 가장 작은 부위에서 유속이 증가하였고, 음압이 크게 나타났다. 기도의 형태는 구개인두와 구인두 부위에서 좁아지는 형태를 가지며, 최소 단면적 영역과 하인두 단면적의 차이가 클수록 유속과 음압의 변화가 크게 나타났다. 비강 부위의 최고 압력과 최소 단면적 영역의 최저 압력의 차이를 의미하는 압력강하는 상기도 저항을 종합적으로 판단할 수 있는 유용한 지표이며, 유량에 따라 증가하였다.

Keywords

References

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  1. 폐쇄성 수면무호흡증 환자의 상하악 전진술 후 상기도 내 유동해석 vol.39, pp.5, 2010, https://doi.org/10.3795/ksme-b.2015.39.5.443