Contacts: Yue Yun, +86 13889168717, Second Department of Anesthesiology First Affiliated Hospital of China Medical University, China Urgent Unblinding Method When serious adverse reactions appear during the experiment, if necessary, the study director can open the emergency envelope to carry out urgent unblinding strategy and record the relevant causes and date in the case report form. Whether the unblinded subjects withdraw from the experiment is decided by investigators and responsible party.