Article History
Received: 6 May 2020
Accepted: 11 June 2020
First Online: 18 June 2020
Ethics approval and consent to participate
: This study protocol was approved by Ajou Institutional Review Board at Aug, 13, 2018 (AJIRB-MED-OBS-18-226). Written informed consent was obtained from all participants.
: Not applicable.
: Long endotracheal tube was registered Korean patent (01–2018-0015745) and applied PCT patent (PCT/KR2019/001557).