The aim of the study is the assessment of the systemic absorption of local anesthetics during continuous epidural infusion for postoperative pain control.

In literature the systemic toxicity of bupivacaine is widely demonstrated, like the minor toxicity of levobupivacaine and ropivacaine at the same anesthetic potency. The are actually no studies in humans confronting levobupivacaine and ropivacaine under the aspect of efficacy and toxicity.The aim of the study is the assessment of the systemic absorption of local anesthetics during continuous epidural infusion for postoperative pain control.

Primary outcome:

Assessment of the plasmatic equimolar concentrations of levobupivacaine and ropivacaine during continuous epidural infusion

Secondary outcome:

Assessment of the safety level of the local anesthetic (major difference between haematic concentration of the local anesthetic and neuro-cardiotoxic dose).

Difference of the analgesic efficacy between levobupivacaine and ropivacaine. Differences in collateral effects due to the local anesthetic: hypotension and sensitive block.

Prospective randomized double-blinded clinical trial

Inclusion Criteria:

• ASA I or ASA II
• Scheduled for major surgery
• written informed consent

Exclusion Criteria:

• ASA III, IV
• Emergency surgery
• Recovery in intensive care unit after surgery
• habitual opioid consumption
• cognitive or mental alterations
• coagulopathy
• piastrinemia < 100.000/mm3