Abstract: Objective To investigate the effect of low-dose esketamine on postoperative delirium (POD) and the levels of inflammatory factors after total hip replacement surgery in the elderly patients with frailty. Methods A total of 60 elderly patients with frailty aged 65 to 85 years undergoing total hip replacement surgery under general anesthesia from August 2021 to August 2022 were enrolled in this study, and were divided into esketamine group and control group, with 30 patients in each group. The esketamine group received 0.2 mg/kg esketamine during induction of anesthesia and the control group received the same volume of saline. Peripheral venous blood was collected 1 d before surgery, 1 d and 3 d after surgery; White blood cell count (WBC), neutrophil to lymphocyte ratio (NLR), the levels of interleukin-6 (IL-6) and high sensitivity C-reactive protein(hs-CRP)were detected. The operation time, blood loss, fluid rehydration, and intraoperative use of sufentanil, propofol, remifentanil and vasoactive drugs were recorded. The mean arterial pressure(MAP) and heart rate(HR)were recorded during anesthesia. The incidence of POD was evaluated with the Confusion Assessment Method(CAM) scale and the adverse reactions within 3 days after operation were recorded. Results Compared with the control group, the incidence rate of POD was significant decreased in the esketamine group. The intraoperative sufentanil consumption in the esketamine group was decreased than that in the control group(P<0.01). On the first and third day after operation, the levels of IL-6 and hs-CRP in the two groups were increased, especially in the control group (P<0.05). The levels of WBC and NLR in the two groups increased first and then decreased. On the first and third day after operation, the levels of WBC and NLR in the control group were significantly higher than those in the esketamine group (P<0.05). Compared with the control group, the levels of MAP and HR in the esketamine group were significantly decreased at different time points during anesthesia (P<0.05). There was no significant difference in the incidence rate of adverse reaction between the two groups. Conclusions The use of low-dose esketamine during induction of general anesthesia can reduce the incidence of POD in the elderly patients with frailty receiving hip replacement surgery, and the mechanism may be related to the inhibition of inflammation and stress reaction.

Key words: esketamine, hip replacement, aged, delirium, frailty, inflammatory factor