Effects of Esketamine Pre-administration on Blood Lymphocyte Subsets and Inflammatory Factors in Early Postoperative Period:

Esketamine is a new antidepressant approved by the US Food and Drug Administration (FDA) in 2019. It has rapid action and accurate treatment effect for refractory severe depression. Studies have shown that esketamine also has significant anti-inflammatory effects. The investigators' previous study found that esketamine has a good preventive effect on inflammatory response, but the effect of preoperative preadministration of esketamine on postoperative systemic immune function and systemic inflammatory response is not clear.

Clinical studies have shown that esketamine (0.25 mg/kg, 40 min infusion time) can rapidly improve the depressive symptoms of patients with treatment-resistant depression. Esketamine is shown to be able to play a neuroprotective role by reducing glial cell activation and the production of inflammatory cytokines such as tumor necrosis factor (TNF-α) and interleukin-6 (IL-6). Esketamine at a dose of 0.2 mg/kg or 0.4 mg/kg has significant antidepressant effects in the treatment of resistant depression. The antidepressant effects of esketamine may be closely related to its anti-inflammatory effect. During cardiopulmonary bypass surgery, anesthesia induction was supplemented with 1-3 mg/kg esketamine, anesthesia maintenance was supplemented with 2-3 mg/kg/h esketamine, anesthesia maintenance time was 283 minutes, the total amount of esketamine was 1580mg on average. Esketamine decreased plasma levels of IL-6 (6 h after opening the aorta) and IL-8 (1 and 6 h after opening the aorta) and increased plasma levels of IL-10 (1 h after opening the aorta). In the investigators' preliminary study on the role of esketamine in systemic inflammation induced by lipopolysaccharide (LPS), the investigators found that in systemic LPS (5 mg/kg)-induced systemic inflammation model, esketamine (10 mg/kg, IP) was administrated twice 24 hours before LPS administration and 10 minutes after LPS administration. The plasma levels of IL-6, IL-17A and interferon γ (IFN-γ) were significantly decreased 24 h after LPS administration in mice. Single administration of esketamine 10 min after LPS administration did not significantly reduce the plasma levels of IL-6 and IL-17A at 24 h. The investigators further found that in mice with LPS (8 mg/kg)-induced systemic inflammation, twice intraperitoneal administration of esketamine (10 mg/kg, IP) 24 hours before LPS administration and 10 minutes after LPS administration also significantly reduced the plasma levels of IL-17A 24 hours after LPS administration. Surgery-induced trauma could cause significant inflammatory responses, manifested by increased expression of pro-inflammatory cytokines. Studies have found that ketamine at a dose of 0.5 mg/kg administrated immediately before chest surgery could reduce the plasma levels of IL-6 and C-reactive protein 24 hours after surgery. However, it remains unclear whether preoperative and immediate postoperative administration of esketamine could improve postoperative immune function and alleviate systemic inflammatory response.

The investigators will include patients subjected to elective surgery strictly according to the inclusion and exclusion criteria to investigate whether preoperative and immediate postoperative administration of esketamine has postoperative anti-inflammatory effects on postoperative delirium, postoperative pain, and postoperative sleep, as well as on total length of hospital stay, in-hospital infection complications, in-hospital mortality, and 90-day readmission rates. Prophylactic administration of esketamine before surgery is expected to provide a new therapeutic strategy for alleviating postoperative systemic inflammation and improving postoperative immune suppression.

Enrolled patients were randomly assigned to two groups: the esketamine preadministration group and the placebo control group. Esketamine at a dose of 0.25 mg/kg (40 min infusion time) or normal saline was given intravenously 24-36 hours before surgery, and esketamine at a dose of 0.25 mg/kg (40 min infusion time) or normal saline was given intravenously immediately after surgery.

Seven tubes of venous blood were collected and sent to the laboratory and immunology department of Union Hospital affiliated to Tongji Medical College, Huazhong University of Science and Technology, 24 hours before and after the first administration of esketamine, and seven tests including blood routine, coagulation, liver function, kidney function, electrolytes, C-reactive protein, myocardial enzyme, BNP, lymphocyte subsets and cytokines were performed. A tube of venous blood was taken at each of the two time points in the study and centrifuged to obtain plasma, which was frozen and stored at -80℃ for ELISA detection of ANP.