title: The Effect of Low-dose Ketamine on Post-caesarean Delivery Analgesia after Spinal Anesthesia.
abstract: BACKGROUND
  Ketamine, an N-methyl-D-aspartate receptor antagonist, might play a role in postoperative analgesia, but its effect on postoperative pain after caesarean section varies with study design. We investigated whether the preemptive administration of low-dose intravenous ketamine decreases postoperative opioid requirement and postoperative pain in parturients receiving intravenous fentanyl with patient-controlled analgesia (PCA) following caesarean section.
  
  
  METHODS
  Spinal anesthesia was performed in 40 parturients scheduled for elective caesarean section. Patients in the ketamine group received a 0.5 mg/kg ketamine bolus intravenously followed by 0.25 mg/kg/h continuous infusion during the operation. The control group received the same volume of normal saline. Immediately after surgery, the patients were connected to a PCA device set to deliver 25-µg fentanyl as an intravenous bolus with a 15-min lockout interval and no continuous dose. Postoperative pain was assessed using the cumulative dose of fentanyl and visual analog scale (VAS) scores at 2, 6, 24, and 48 h postoperatively.
  
  
  RESULTS
  Significantly less fentanyl was used in the ketamine group 2 h after surgery (P = 0.033), but the difference was not significant at 6, 12, and 24 h postoperatively. No significant differences were observed between the VAS scores of the two groups at 2, 6, 12, and 24 h postoperatively.
  
  
  CONCLUSIONS
  Intraoperative low-dose ketamine did not have a preemptive analgesic effect and was not effective as an adjuvant to decrease opioid requirement or postoperative pain score in parturients receiving intravenous PCA with fentanyl after caesarean section.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
authors.forename: Seung Yeup
authors.initials: SY
authors.lastname: Han
authors.forename: Hee Cheol
authors.initials: HC
authors.lastname: Jin
authors.forename: Woo Dae
authors.initials: WD
authors.lastname: Yang
authors.forename: Joon Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Seong Hwan
authors.initials: SH
authors.lastname: Cho
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Chae
authors.forename: Jeong Seok
authors.initials: JS
authors.lastname: Lee
authors.forename: Yong Ik
authors.initials: YI
authors.lastname: Kim
keywords: caesarean delivery; ketamine; patient-controlled analgesia; preemptive analgesia; spinal anesthesia