Within the 48 AH , the incidence of nausea and vomiting in group S was 26.7 % ( 8/30 ) , which was obviously higher than that in group DS ( 6.7 % , 2/30 , P < 0.05 ) ; the incidence of drowsiness in group S was 20.0 % ( 6/30 ) , which was significantly higher than that in group DS ( no patient , P < 0.05 ) .