Effect of ketamine added to intravenous patient-controlled analgesia on postoperative nausea and vomiting in patients undergoing lumbar spinal surgery

Abstract

Opioid based intravenous patient-controlled analgesia (IV PCA) is a safe and effective way of postoperative analgesia while increases the postoperative nausea and vomiting (PONV). Mixture of subanesthetic dose of ketamine in IV PCA was reported to reduce the usage of opioid with improved quality of postoperative analgesia. In this randomized, double-blind, prospective study, we evaluated whether the ketamine, mixed to fentanyl based IV PCA, could reduce the opioid consumption and PONV in patients with high risk for PONV undergoing lumbar spinal surgery.Fifty nonsmoking female patients between 20 ~ 65 years old undergoing lumbar spinal surgery were selected and randomized into 2 groups, as the control group and the ketamine group. Immediately after the induction of anesthesia, 0.5 mg/kg of ketamine or the same volume of normal saline was injected in the patients of ketamine and control group, respectively. IV PCA was composed with fentanyl 20 ㎍/kg and ondansetron 8 mg (total volume 180 ml, basal rate 2 ml/hr, bolus 2 ml, lock-out-time 15 minutes). Ketamine 3 mg/kg was mixed to IV PCA in the ketamine group and the same volume of normal saline was mixed to IV PCA in the control group. Pain, nausea, vomiting, other side effects, the volume of IV PCA used, and additional use of analgesics or antiemetics were recorded in the postanesthesia care unit and at 6, 12, 24, 36 and 48 hr after the operation. Patient’s characteristics were similar between the 2 groups. The intensity of pain was similar in both groups, whereas the volume of IV PCA used at 48 hr after operation was significantly less in the ketamine group than in the control group. Additional use of analgesics and antiemetics, the incidence and intensity of PONV were not different between the groups. The incidence of dizziness was significantly higher in the ketamine group. Although addition of subanesthetic dose of ketamine to fentanyl based IV PCA demonstrated opioid sparing effect, regarding no beneficial effect on the incidence of PONV and the increased incidence of dizziness in the ketamine group, it was not likely to exert clinical advantage in high risk patient for PONV undergoing lumbar surgery.