To observe the clinical efficacy and safety of subanesthetic dose of esketamine injection and quadratus lumborum block in elderly patients undergoing radical resection of colorectal cancer.

Patients undergoing radical resection of colorectal cancer were divided into treatment group and control group according to the anesthesia method. Both groups underwent bilateral quadratus lumborum block under ultrasound guidance. Anesthesia induction was performed with etomidate injection at a dose of 0.1-0.3 mg·kg^-1, sufentanil injection at a dose of 0.3-0.6 μg·kg^-1, midazolam injection at a dose of 0.04-0.06 mg·kg^-1, and cisatracurium injection at a dose of 0.2 mg·kg^-1. Anesthesia was maintained with propofol injectation emulasion 4-8 mg·kg^-1·h^-1, remifentanil for injection 0.15-0.3 μg·kg^-1·min^-1, and dexmedetomidine injection 0.2-1.0 μg·kg^-1·h^-1. The treatment group received a single intravenous injection of 0.25 mg·kg^-1 esketamine injection 5 min before surgery, while the control group received routine anesthesia management without esketamine injection intervention. Both groups received intravenous patient-controlled analgesia postoperatively. Hemodynamics, analgesia and sedation, postoperative opioid consumption, and recovery quality were compared between the two groups, and safety was evaluated.

A total of 108 patients were enrolled, the treatment group included 52 cases and the control group included 56 cases. The mean arterial pressure (MAP) at T₃ in the treatment and control groups were (86.04±6.43) and (83.20±6.80) mmHg, respectively; the heart rate (HR) at T₃ were (76.21±5.56) and (73.96±5.31) beats·min^-1, respectively; the numerical rating scale (NRS) at 12 h postoperatively were (2.04±0.77) and (2.29±0.65) points, respectively; sufentanil consumption were (88.63±11.28) and (94.30±12.22) μg, respectively; the effective pressing times of the analgesia pump within 24 h postoperatively were (5.65±1.17) and (6.23±1.40) times, respectively, and the effective pressing times of the analgesia pump within 24-48 h postoperatively were (7.06±1.51) and (7.89±2.18) times, respectively; the awakening time were (21.25±4.58) and (23.68±4.87) min, respectively, and the length of stay in the postanesthesia care unit (PACU) were (36.23±6.91) and (40.05±7.42) min, respectively. The differences were all statistically significant (P<0.05, P<0.01). The adverse drug reactions in the treatment group were dizziness, nausea and vomiting, while the adverse drug reaction in the control group was skin pruritus. The total incidence of adverse reactions in the treatment and control groups was 3.85% (2 cases/52 cases) and 1.79% (1 case/56 cases), respectively, and the difference was not statistically significant (P>0.05).

The application of subanesthetic dose of esketamine and quadratus lumborum block in elderly patients undergoing radical resection of colorectal cancer can effectively reduce postoperative opioid consumption, provide good sedation and analgesia, maintain hemodynamic stability, protect lung function, and improve recovery quality. It has little impact on cognitive function and sleep quality, and has good safety.