Effect of low-dose esketamine on postoperative delirium in elderly patients undergoing hip arthroplasty

  Background  Postoperative delirium is a common postoperative neurological complication which has no effective preventive and therapeutic measures in elderly patients with major surgery.

  Objective  To investigate the effect of low-dose esketamine on the occurrence of postoperative delirium in elderly patients undergoing hip arthroplasty.

  Methods  Elderly patients with elective degenerative joint disease who underwent hip arthroplasty under general anesthesia from September 2020 to October 2021 in Tangshan Gongren Hospital, aged 65-75 years old, were randomly divided into esketamine group (group A) and control group (group B). Patients in group A were induced with intravenous injection of esketamine 0.2 mg/kg, midazolam 0.03-0.06 mg/kg, alfentanil 20-40 μg/kg, etomidate 0.1-0.3 mg/kg and rocuronium 0.6 mg/kg, while patients in group B were induced with intravenous injection of saline in the same volume as esketamine, midazolam 0.03-0.06 mg/kg, alfentanil 20-40 μg/kg, etomidate 0.1-0.3 mg/kg and rocuronium 0.6 mg/kg. Patients in both groups were maintained by intravenous anesthesia. The mean arterial pressure (MAP) and heart rate (HR) were recorded before anesthesia induction (T₀), 5 minutes after induction (T₁), 10 minutes after induction (T₂), at the beginning of surgery (T₃), and at the end of surgery (T₄). The levels of S100 calcium binding protein beta (S100β), the inflammatory factors tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in venous blood were measured by enzyme-linked immunosorbent assay at the following time points: induction of anesthesia (T₀), the end of surgery (T₄), 1 day after surgery (T₅), and 3 days after surgery (T₆). The 3D-CAM scale was used to assess the occurrence of delirium within 5 days after surgery.

  Results  There was no significance in age, sex ratio, ASA, BMI and operation time between the two groups (P>0.05). MAP increased significantly in both groups at T₁ and T₂ compared with T₀ (multiple correction, P<0.013), MAP decreased significantly in group A at T₁ and T₂ compared with group B (P<0.05); HR increased significantly in both groups at T_1-3 compared with T₀ (multiple correction, P<0.013), and the HR of patients in group A was significantly lower than that of group B at the time point of T₁ and T₂ (P<0.05); the levels of TNF-α and IL-6 in venous blood in both groups were significantly increased at T_4-6 compared with T₀ (multiple correction, P<0.017), and TNF-α and IL-6 levels in group A were significantly lower than those of group B at T_4-6 (P<0.05), the level of IL-10 in patients in both groups were significantly increased at T_4-6 compared with T₀ (multiple correction, P<0.017), and the level of IL-10 in group A increased significantly than group B at T_4-6 (P<0.05); S100β level in venous blood in both groups was significantly higher at T_4-6 compared with T₀ (multiple correction, P<0.017), and the S100β level in group A was significantly lower than group B at T₄ and T₅ (P<0.05); the incidence of postoperative delirium was 3.3% in group A and 20.0% in group B. Compared with group B, the incidence of postoperative delirium decreased in group A (P<0.05).

  Conclusion  Esketamine reduces the occurrence of postoperative delirium in elderly patients undergoing hip arthroplasty, and the mechanism may be related to inflammatory response suppression and brain injury reduction.