The impact of ketamine on delayed neurocognitive recovery in elderly patients undergoing spinal anaesthesia for orthopaedic procedures, a pilot study

Objective: Delayed neurocognitive recovery is an objectively measurable decline in the cognitive status at varying intervals after surgery under both general and spinal anaesthesia. In this study, we used the Short Portable Mental Status Questionnaire to evaluate the protective effect of ketamine infusion on cognitive function of elderly patients undergoing spinal anaesthesia for orthopaedic procedures. Methods: A randomised, double-blinded placebo-controlled trial. Forty-two geriatric patients listed for elective orthopaedic surgery under spinal anaesthesia were randomly assigned to receive an intravenous infusion of either ketamine (0.3mg/kg) or isotonic saline (control group) after receiving spinal anaesthesia, which continued throughout the procedure. Cognitive performance was evaluated, as a primary outcome, with Short Portable Mental Status Questionnaire. Results: Baseline cognitive performance was comparable in both groups. Patients in the ketamine group showed statistically significant fewer errors in the postoperative Short Portable Mental Status Questionnaire compared with the baseline evaluations (p = 0.038). Patients in the ketamine group showed significantly lower verbal numerical scale scores than the control group (p = 0.04) at six hours after surgery. Conclusion: Elderly patients undergoing spinal anaesthesia showed a better cognitive status after receiving an intravenous infusion of 0.3mg/kg ketamine. However, further research with a larger sample size and different assessment tools might be required to verify our results.