The Effects of Ketamine on Cognitive Function in Elderly Patients Undergoing Ophthalmic Surgery: A Pilot Study

BACKGROUND: Acute postoperative cognitive dysfunction is characterized by neurocognitive dysfunction and confusion. In this study, we compared the cognitive status of a geriatric population undergoing ophthalmic surgery, as assessed by the Short Portable Mental Status Questionnaire (SPMSQ) before and after ketamine administration. METHODS: Eighty patients were enrolled and randomly assigned in a double-blind study to receive either ketamine (0.3 mg/kg dose) or physiologic solution (control group). Sixty-five (control, n = 32; ketamine, n = 33) patients completed the trial. Cognitive performance was assessed with an abbreviated version of the SPMSQ. Measurements of analgesia, sedation, intraocular pressure, and hemodynamic variables were recorded. RESULTS: With respect to cognitive performance, the baseline evaluation was similar for the control and ketamine groups. Postoperative evaluation showed an improvement only in the ketamine group. No increase in intraocular pressure or a secondary nystagmus was observed. The average dose of midazolam was higher in the control group, but the difference was not clinically significant. After surgery, analgesic behavior was better in the ketamine group than in the control group. There were no differences between groups in the sedation scale or in hemodynamic variables. CONCLUSIONS: The administration of 0.3 mg/kg ketamine during ophthalmic surgery in geriatric patients changed their cognitive status as assessed by the SPMSQ, decreased the required dose of anesthetics, and produced no increase in intraocular pressure or in hemodynamic variables. However, because the evaluation only analyzed the immediate effects of the administered drug, further research will be required to examine the impact of ketamine on the postoperative cognitive performance of geriatric patients before the drug can be formally recommended for this purpose.