Sufentanil consumption ( 41.5021.80 vs. 89.7035.22 g ; P < 0.01 ) after 48 hours , time to bowel recovery ( 1.800.70 vs. 3.151.04 d ; P < 0.01 ) , incidence of nausea and vomiting ( 1.750.72 vs. 2.400.68 ; P < 0.05 ) , and mean length of hospitalization ( 5.62.44 vs. 7.352.85 d ; P < 0.01 ) were significantly reduced , and the sedation score and liver function change were also comparable between the 2 groups .