Transversus Abdominis Plane Block on Stress Response

Participants in this group receive ultrasound-guided TAP block under bilateral costal margin with multiple injections of 40ml 0.375% ropivacaine after the induction of general anesthesia, 30 minutes later the surgery will be started.

Participants in the Epidural group receive a epidural block (T8-9) with 2 mL of 1.6% lidocaine as a test dose before induction. After a successful placement of epidural catheter, the block then is established with 5 mL of 0.375% ropivacaine and continous infusion of 0.375% ropivacaine(5 mL/h) during the surgery.

The Control group receives standard IV-inhaled general anesthesia.