Received: 4 July 2020
Accepted: 27 January 2021
First Online: 6 February 2021
Ethics approval and consent to participate
: This educational study was done using a verbal consent, which was approved by the Ethics Committee and Institutional Review Board of Keio University Hospital (IRB No. 20190174). In our hospital, a written consent was not applicable regarding the educational study as any patients were not involved.
: Not applicable.
: The authors declare no conflict of interest.