Opioids have been used for analgesia since many years, but despite potent analgesia they are also associated to side effects, including opioid induced Hyperalgesia (OIH).

OIH in the surgical setting is debated, and may predispose patients to higher analgesic consumption in the preoperative period, and peripheral and central sensitization. The aim of the study is to compare remifentanil-based vs non opioid analgesia (clonidine, lidocaine, ketamine) for intraoperative management of patients undergoing laparoscopic left hemicolectomy, with the hypothesis that non- opiod treated patients will have lower morphine consumption in the first 24 hours after surgery. Peripheral and central hyperalgesia will be tested with Von Frey hairs and pin-prick to evaluate acute CNS (Central Nervous System) sensitization after surgery. Acute and persistent (1 and 3 months) pain will be registered, together with any side effect and parameters of surgical rehabilitation.

Inclusion Criteria:

• left hemicolectomy
• signed informed consent
• >18 ys

Exclusion Criteria:

• >90 ys <18 ys
• no consent
• pregnancy
• psychiatric disease
• cardiac failure, aortic or mitral valve severe stenosis
• kidney or hepatic failure
• atrio-ventricular type II block
• immunodepression
• emergency surgery
• ICU admittance
• drug or alcohol abuse
• chronic pain