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Endotracheal intubation using semi-rigid optical stylet in simulated difficult airways of high grade modified Cormack and Lehane laryngeal views
Anesth Pain Med 2018;13(3):329-35
Published online July 31, 2018
© 2018 The Korean Society of Anesthesiologists.

Young-Jin Moon1, Sung-Hoon Kim1, Hyun Kang2, Eun Ha Suk3 , Jae-Hyoung Cho3, Seong-Soo Choi1, Wook-Jong Kim1, and Seung-Woo Ku1
Department of Anesthesiology and Pain Medicine, 1Asan Medical Center, University of Ulsan College of Medicine, 2Chung-Ang University College of Medicine, Seoul, 3Kwangju Christian Hospital, Gwangju, Korea
Correspondence to: Eun Ha Suk, M.D. Department of Anesthesiology and Pain Medicine, Kwangju Christian Hospital, 37 Yangrim-ro, Nam-gu, Gwangju 61661, Korea Tel: 82-62-650-5156 Fax: 82-62-650-5381 E-mail: ORCID
Received October 11, 2017; Revised December 13, 2017; Accepted December 14, 2017.
cc This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: Endotracheal intubation in patients with compromised cervical vertebrae and limited mouth opening is challenging, however, there are still limited options available. Among devices used for managing difficult airways, the Clarus Video System (CVS) might have considerable promise due to its semi-rigid tip. We evaluated the performance of CVS in patients with simulated difficult airways.
Methods: Philadelphia cervical collars were applied to 74 patients undergoing general anesthesia. The degree of simulated difficult airway was assessed by observing laryngeal view using McCoy laryngoscope; modified Cormack and Lehane grade (MCL) ≥ 3a (high-grade group, n = 38) or ≤ 2b (low-grade group, n = 36). Subsequently, patients were intubated using CVS by a blinded practitioner. We evaluated total time to intubation, intubation success rate, and conditions of intubation.
Results: Intubation took significantly longer time for the high-grade group than that for the low-grade group (38.2 ± 25.9 seconds vs. 27.9 ± 6.2 seconds, time difference 10.3 seconds, 95% confidence interval: 1.4–19.2 seconds, P < 0.001). However, CVS provided similar high intubation success rates for both groups (97.4% for the high-grade and 100% for the low-grade group). During intubation, visualization of vocal cords and advancement into the glottis for the high-grade group were significantly more difficult than those for the low-grade group.
Conclusions: Although intubation took longer for patients with higher MCL laryngeal view grade, CVS provided high intubation success rate for patients with severely restricted neck motion and mouth opening regardless of its MCL laryngeal view grade.
Key Words : Clarus Video System, Intubation, Limited neck motion, Neck collar.

July 2018, 13 (3)
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