Abstract
PURPOSE: The aim of this study is to investigate the effects of administering low-dose esketamine during anesthesia induction on the occurrence of postoperative delirium (POD) and postoperative cognitive function in elderly patients with preoperative anxiety. PATIENTS AND METHODS: Elderly patients aged 60-80 years and with preoperative anxiety who were undergoing surgery for gastrointestinal tumors were enrolled. The patients were randomly divided into an esketamine group or a placebo group. Upon intravenous induction of general anesthesia, the placebo group received normal saline, while the esketamine group received a subanesthetic dose (0.25 mg/kg) of esketamine. The primary outcome was the incidence of POD and the Mini-Mental State Examination (MMSE) score within 7 days after the operation (d1 to d7). Secondary outcomes included perioperative hemodynamic adverse events, postoperative anxiety, postoperative pain score, and analgesic consumption. RESULTS: 118 patients were screened for eligibility, and 100 were recruited and analyzed. The incidence of POD within 7 days after surgery in the esketamine group was significantly lower than the placebo group (24.00% vs 48.00%, P < 0.05). The MMSE scores at postoperative day1 (d1) were significantly higher in the esketamine group than placebo group (29.00 [28.00-30.00] vs 27.25 [25.00-29.00], Bonferroni-adjusted P = 0.0014). The esketamine group had a lower cumulative incidence of delayed neurocognitive recovery (dNCR) within 7 days after surgery (26.00% vs 54.00%, P < 0.05). When compared to the placebo group, esketamine group had lower incidence of bradycardia and hypotension events during anesthesia induction period (P < 0.05), and the visual analogue anxiety (VAS-A) score on d1 was lower (Bonferroni-adjusted P < 0.05). Moreover, the esketamine group had significantly lower plasma concentrations of serum levels of Interleukin-6 (IL-6) and S100 calcium-binding protein β (S100β) on d1 (Bonferroni-adjusted P < 0.05). CONCLUSION: In elderly patients with preoperative anxiety who undergo gastrointestinal tumor surgery, administering a low-dose intravenous esketamine injection (0.25 mg/kg) during anesthesia induction can decrease the incidence of POD and improve early postoperative cognitive function.