The prescription of PCEA of group L and R were 2 g/L levobupivacaine+0.04 g/L morphine(Mor)+0.02 g/L droperidol(Dro) and 2 g/L ropivacaine+0.04 g/L Mor+0.02 g/L Dro.

• R组(n=30):镇痛药为2g/L罗哌卡因(Rop)+0.；04g/LMor+0