Although deep anesthesia can produce skeleton muscle relaxation,unnecessary deep anesthesia often had adverse cardiac effects and was related to 2-year mortality in cancer patients.The use of muscle relaxants allowed the depth of anesthesia to be optimized.However, for many anesthesiologists,in fear of residual postoperative neuromuscular blockade,intraoprative administration of muscle relaxants had to be minimized in spite of poor surgical conditions.

This study, however, is designed to test the hypothesis that profound neuromusclular blockade reduces muscle trauma caused by self-retaining retractor and thus cut down postoperative analgesic requirement.On the other hand,profound muscle relaxation can decrease postoperative diaphragmatic dysfunction and abdominal muscle trauma, which can improve postoperative pulmonary function.

Inclusion Criteria:

• ASA 1~2,scheduled to undergo upper abdominal surgery by midline incision

Exclusion Criteria:

• neuromuscular disorder
• history of malignant hyperthemia
• allergy to medications used during general anesthesia