Preemptive low-dose of ketamine does not effective on anesthetic consumption, perioperative analgesic requirement and postoperative pain, nausea and vomiting in painful ophthalmic surgery

BACKGROUND Ketamine, a non-competitive NMDA (N-Methyl-D-Aspartate) receptor antagonist, is recognized as an intraoperative anesthetic agent. Increasing interest in the use of low-dose ketamine for postoperative analgesia has developed in part because of its NMDA-antagonistic properties, which may be important in attenuating central sensitization and opioid tolerance. Despite of many trial evaluations which have been done on the effect of low-dose ketamine in postoperative pain, the role of ketamine, as a component of perioperative analgesia, remains unclear. We evaluated the analgesic effect of low-dose ketamine during anesthesia induction in painful ophthalmic surgery. MATERIALS AND METHODS After institutional approval and written informed consent, 88 patients undergoing retinal detachment, strabismus, and keratoplasty surgery aged 18-80 years old were randomly divided intoequal case and control groups. Anesthesia was induced with sodium thiopental, fentanyl, atracurium, and liducaine, and maintained with N2O, O2, and propofol. Ketamine 0.5 mg/kg was administered intravenously to patients in the case group during anesthetic induction. Mean blood pressure and pulse rate were listed in questionnaire every 5 minutes. The consumption of anesthetic, perioperative additional analgesic, extubation time, postoperative pain and nausea scores (based on Visual Analog Scale), vomiting frequency, and the recovery time were recorded. RESULTS There were no differences in the recovery time (17.3 ± 3.4 in the case group vs. 16.3 ± 3 in the control group, P < 0.05), postoperative pain scores (5 ± 1 in the case group vs. 5.6 ± 2 in the control group, P < 0.05), the consumption of anesthetic (9376.9 ± 1245.8 in the case group vs. 9012.9 ± 1620 in the control group, P < 0.05), the analgesic requirements (1000 in the case group vs. 940.9 ± 135.6 in the control group, P < 0.05), and perioperative additional analgesic (63.4 ± 26.5 in the case group vs. 69.4 ± 25.6 in the control group, P < 0.05) between two groups. The extubation time in the case group (13.59 ± 4.83) was significantly shorter than in the control group (15.9 ± 3.6) (P = 0.01). CONCLUSION This study demonstrates that a low dose administration of ketamine during anesthesia induction in retinal detachment, strabismus, and keratoplasty surgery improves the extubation time but have no effect on postoperative pain, nausea and vomiting, and perioperative additional analgesic requirements.