The influence of low-dose s-ketamine on postoperative delirium and cognitive function in older adults undergoing thoracic surgery

Abstract

Abstract Background Postoperative delirium (POD) and cognitive dysfunction (POCD) are common complications following thoracic surgery, particularly in patients aged 65 years and above. These complications can significantly affect recovery and increase healthcare costs. This study investigates the effects of low-dose S-ketamine on reducing POD and POCD in this patient demographic. Methods In this retrospective cohort study, medical records of patients aged ≥ 65 years who underwent elective thoracic surgery from January 2019 to August 2023 were reviewed. Patients were categorized into S-ketamine and Control groups based on intraoperative S-ketamine exposure. POD was assessed using the Confusion Assessment Method (CAM), while cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA) at baseline, 1 week, 1 month, and 6 months post-surgery. Intraoperative and postoperative parameters, including hemodynamic stability, blood loss, pain scores, and ICU stay length, were also recorded. Results The study comprised 140 participants, with 70 in each group. The S-ketamine group demonstrated a significantly lower incidence of POD at 7 days post-surgery (12.0% vs. 26.7%, P < 0.001), and reduced POCD at 1 month (18.7% vs. 36.0%, P < 0.05) and 6 months (10.7% vs. 21.3%, P < 0.05). The Ketamine group had a significantly higher median MoCA score compared to the Control group both at 1 month (P = 0.021) and 6 months (P = 0.007). Adverse events, such as infection, bleeding, and respiratory failure, showed no significant differences between the groups, suggesting a safe profile for S-ketamine. Conclusion Administering low-dose S-ketamine during thoracic surgery in patients aged 65 years and above significantly reduces the incidence of POD and POCD, highlighting its neuroprotective potential. These findings advocate for the inclusion of S-ketamine in anesthetic protocols to improve postoperative outcomes and reduce healthcare costs in this patient population.

Keywords

• Postoperative delirium
• Cognitive dysfunction
• Older patients
• Thoracic surgery
• S-ketamine
• Neuroprotection