Lidocaine and ketamine both are being used for perioperative analgesia. Perioperative lidocaine infusion has been shown to reduce postoperative pain and opioid consumption. Perioperative low dose Ketamine has shown improved postoperative pain and reduced opioid usage. We therefore tested the hypothesis that the combination would provide better analgesia in the milieu of intrathecal morphine.

All study participants were monitored according to American Society of Anesthesiologists guidelines. All received intrathecal morphine (300 to 400 mcg) at L3-4 interspace via 25 G Whitacre needle. Participants were then randomized (computer generated) into one of four groups.

General anesthesia was induced and endotracheal intubation was done. Immediately, after intubation, Lidocaine group (L) received a Lidocaine infusion at 0.33 mg/kg/h.

The Ketamine group (K) received a ketamine infusion at 70 mcg/Kg/h. The Lidocaine-Ketamine group (LK) received a Lidocaine infusion at 0.33 mg/kg/h plus a Ketamine infusion at 70 mcg/Kg/h.

The control group (P) received a normal saline infusion to keep the blind. The infusions were stopped approximately 30-45 minute before the completion of surgery.

All participants received a hydromorphone patient-controlled analgesia (PCA) via a pump. All were given acetaminophen 650 mg every 6 hrs for 4 days.

Postoperatively, participants were monitored for nausea, vomiting, sedation, respiratory depression, light-headedness, perioral numbness, pruritus, disturbed dreams and hallucinations.

Postoperative Hydromorphone consumption for the first, second and third day was recorded from the chart maintained by acute pain service team who were blinded to the group assignment.

After the operation, study participants were interviewed at regular intervals by a blinded investigator about their current pain level, as well as satisfaction with pain management. They were also be questioned regarding the presence and severity of opioid-related side effects (nausea, vomiting, sedation, respiratory depression and, pruritus) and light-headedness, perioral numbness, disturbed dreams and hallucinations. Hospital charts were reviewed and data collected to analyze time to request for additional analgesia and total consumption of opioids, non-opioid analgesics, anti-emetics, and antipruritics within the first 72 hours postoperatively.

Inclusion Criteria:

• ASA physical status 2-4
• Elective major liver resection
• Signed informed consent

Exclusion Criteria:

• ICU admission after surgery
• tracheal extubation not planned after surgery
• language barrier
• mental impairment
• severe coagulopathy
• chronic pain or opioid dependance or both
• alcohol/substance abuse
• allergy to the study drugs
• refusal for spinal
• infection at site of spinal

All persons are blinded as the drug is formulated by the investigator who is not the care giver or outcomes assessor