Patients undergoing open colorectal surgery were randomly divided into two groups: Intravenous Lidocaine (IV-Lido) vs Intravenous Ketamine (IV-Keta).

For the IV-Lido group, patients received a loading dose of Lidocaine than a continuous infusion over twenty-four hours.

For the IV-Keta goup, patients received a loading dose of Ketamine than a continuous injection of Ketamine over twenty-four hours.

Plasma concentrations of Interleukin-6(IL-6) were measured preoperatively before anesthetic induction and at twenty-four hour post operatively.

Patients undergoing open colorectal surgery with tumor resection were randomised prospectively into two groups: Intravenous Lidocaine (IV-Lido) vs Intravenous Ketamine (IV-Keta).

For the IV-Lido group (n=25), patients received a loading dose of 1.5 mg/kg of Lidocaine than a continuous infusion of 1.5 mg/kg/h over twenty-four hours.

For the IV-Keta goup(n=25), patients received a loading dose of 0.15mg/kg of Ketamine than a continuous injection of 0.15 mg/kg/h of Ketamine over twenty-four hours.

For both groups, plasma concentrations of Interleukin-6(IL-6) were measured preoperatively before anesthetic induction and at twenty-four hour post operatively. Plasma IL-6 concentrations at each point were compared between the groups.

INCLUSION CRITERIA:

• Patients aged 18 or older.
• American society of anesthesiologists' (ASA) physical status of I-III.
• Elective open colorectal surgery.

NON INCLUSION CRITERIA:

• Patients with contraindications to lidocaine or ketamine.
• Corticosteroid therapy within the last 6 months.
• History of immunosuppressive therapy.
• History of surgery in the last 3 months.
• Personal medical history of inflammatory bowel disease.
• Personal medical history of cardiac arrythmias or conduction disorders.
• Alcohol or drug abuse.
• Chronic use of opioids or benzodiazepines.

EXCLUSION CRITERIA:

• Severe intraoperative complications.
• Duration of surgery longer than 5 hours.