Group A had lower VAS than group B at 1 , 4 , 8 , 12 , 24 h after surgery ( P < 0.05 ) , less PCA demand ( 2.9 1.6 vs 9.1 1.8 ) ( P < 0.05 ) and less PCA sufentanil consumption ( ( 69.1 5.8 ) g vs ( 92.6 6.9 ) g ) ( P < 0.05 ) , thus less post-operative nausea or vomiting and higher satisfaction ( P < 0.05 ) .