Intravenous sub-anesthetic dose ketamine for perioperative analgesia in spinal fusion surgery

Abstract

Objective : To compare postoperative analgesic effect of low dose ketamine administered during anesthesia with placebo in spinal fusion surgery.

Method : This study was a randomized double blinded controlled trial. 38 patients who underwent elective spinal fusion surgery in Mahasarakham hospital were randomly assigned to K and P groups. 19 patients in group K received ketamine 0.3 mg/kg pre-incisional intravenously bolus then continuously infusion 0.15 mg/kg/hr during anesthesia. 19 patients in group P received normal saline in the same dose. Cumulative intravenous morphine consumption at 24 postoperative hours, time to first morphine requirement, numerical rating scale and side effects were recorded.

Results : Mean of cumulative intravenous morphine consumption at 24 hours was significantly reduced in K group compared with P group (8.316±6.37 and 13±6.67, respectively, p=0.033).Morphine accumulation at 15, 30, 45, 60 minutes in PACU (p=0.008, 0.008, 0.009, 0.015) and 0, 1, 24 hours at ward were significantly lower in K group (p=0.008, 0.032 ,0.037).The first numerical rating scale score in PACU was significantly lower in K group (p=0.018). No adverse effect of low dose ketamine.

Conclusion : Intraoperative ketamine is an effective adjuvant therapy. The combination of intravenous sub-anesthetic dose ketamine and morphine during anesthesia in spinal fusion surgery significantly reduce 63.97 % intravenous morphine consumption and no undesirable effect in the first 24 hours after procedure.