Endoscopic submucosal dissection (ESD) is an expert endoscopic technique for en bloc resection of mucosal cancers in the esophagus, stomach, and colon.1–3 During the procedure, the ESD operator must concentrate on the endoscopy monitor to avoid complications and to complete the treatment. However, in some situations, it becomes difficult to operate the endoscope during ESD, and the operator may be forced to view the monitor from a difficult posture. When performing ESD, the operator must also monitor the patient’s vital signs carefully.