The dexmedetomidine group ( Group D , n = 34 ) received a continuous infusion of dexmedetomidine at a rate of 0.4 g kg ( -1 ) hour ( -1 ) from the induction of anesthesia until the end of the ST position , while the control group ( Group C , n = 34 ) received an equal volume of physiologic saline at the same rate under conventional general anesthesia with sevoflurane and remifentanil .