8Bonnet E,Vesinet C.How can we improve the efficacy of morphine analgesia without increasing adverse effects?[J].Can Anaesthiol,1994,42(2):191-194.
9Schmid RL,Sandler AN,Katz J.Use and efficacy of low-dose ketamine in the managementof acute postoperative pain:a review of current techniques and outcomes[J].Pain,1999,82(2):111-125.
