To observe the clinical efficacy and safety of continuous infusion of extremely low-dose dexmedetomidine hydrochloride injection combined with remifentanil hydrochloride for injection and propofol emulsion injection in elderly patients undergoing total hip arthroplasty (THA).

Elderly patients undergoing THA were divided into treatment group and control group according to the administration method. The control group was induced with intravenous injection of sufentanil citrate injection at a dose of 0.3 μg·kg^-1, propofol emulsion injection at a dose of 1.0-2.5 mg·kg^-1, and rocuronium bromide injection at a dose of 0.6-0.9 mg·kg^-1. Anesthesia was maintained with intravenous infusion of propofol emulsion injection at a dose of 4-6 mg·kg^-1·h^-1 and remifentanil hydrochloride for injection at a dose of 0.1-0.2 μg·kg^-1·h^-1. The treatment group received dexmedetomidine hydrochloride injection 0.2-0.5 μg·kg^-1 before anesthesia induction, followed by ultra-low dose dexmedetomidine hydrochloride injection 0.1-0.2 μg·kg¹·h^-1 intravenous infusion from after anesthesia induction to 30 min before the end of the operation, with other treatments the same as the control group. The vital signs of the two groups were compared after entering the room (T₀), immediately after tracheal intubation (T₁), at the time of upper tourniquet (T₂), when necrotizing bone and tissue were removed (T₃), when prosthesis was implanted (T₄), when tourniquet was released (T₅) and immediately after extubation (T₆) and the modified alert sedation/score (MOAA/S) was improved; the dosage of anesthetics, the occurrence of postoperative delirium, preoperative and postoperative neuronal injury markers, and neurotransmitter markers were compared between the two groups, and safety was evaluated.

A total of 120 patients were enrolled, including 63 cases in the treatment group and 57 cases in the control group. At T₁, the heart rate (HR) of treatment group and control group were (79.68±7.34) and (76.79±8.40) times·min^-1, respectively; at T₂, they were (81.43±7.37) and (78.68±7.49) times·min^-1, respectively; at T₃, they were (83.83±7.53) and (80.35±7.14) times·min^-1, respectively; at T₄, they were (82.63±6.90) and (79.77±7.39) times·min^-1, respectively; at T₅, they were (81.27±7.31) and (78.16±7.51) times·min^-1, respectively; at T₆, they were (86.16±7.32) and (83.74±7.31) times·min^-1, respectively. The heart rate of treatment group at each time were all significantly higher than those of control group (all P<0.05). At T₁, the mean arterial pressure (MAP) of treatment group and control group were (80.29±9.89) and (75.32±9.73) times·min^-1, respectively; at T₂, they were (82.10±10.00) and (77.18±9.82) times·min^-1, respectively; at T₃, they were (83.16±9.95) and (79.46±10.06) times·min^-1, respectively; at T₄, they were (82.83±9.58) and (77.19±9.92) times·min^-1, respectively; at T₅, they were (81.30±9.59) and (76.09±9.82) times·min^-1, respectively; at T₆, they were (84.14±9.87) and (82.12±9.97) times·min^-1, respectively. The MAP of treatment group at each time were all significantly higher than those of control group (all P<0.05). At T₁, the MOAA/S of treatment group and control group were (2.05±0.28) and (2.23±0.46) score, respectively; at T₂, the scores were (1.92±0.33) and (2.09±0.51) score, respectively; at T₃, the scores were (1.95±0.42) and (2.09±0.34) score, respectively; at T₄, the scores were (1.92±0.33) and (2.11±0.36) score, respectively; at T₅, the scores were (1.92±0.33) and (2.07±0.37) score, respectively; at T₆, the scores were (3.30±0.73) and (3.77±0.80) score, respectively. The MOAA/S scores of treatment group at each time were all significantly lower than those of control group (all P<0.05). The intraoperative propofol dosage in treatment group and control group were (381.81±46.48) and (407.25±49.36) mg, respectively; the intraoperative remifentanil dosage were (14.43±1.82) and (15.14±2.00) μg, respectively; the incidence of postoperative delirium at 72 h were 15.87% and 33.33%, respectively; the postoperative 24 h central nervous system-specific protein (S100β) levels were (0.59±0.11) and (0.66±0.14) μg·mL^-1, respectively; the postoperative 24 h glial fibrillary acidic protein (GFAP) levels were (0.87±0.29) and (1.02±0.22) ng·mL^-1, respectively; the postoperative 8 h 5-hydroxytryptamine (5-HT) levels were (168.91±18.25) and (159.35±17.54) μg·L^-1, respectively, with statistically significant differences (all P<0.05). The total incidence of adverse drug reactions were 12.70% in treatment group and 22.81% in control group, respectively, with no statistically significant difference (P>0.05).

Continuous infusion of extremely low-dose dexmedetomidine hydrochloride injection combined with remifentanil hydrochloride for injection and propofol emulsion injection in elderly patients undergoing THA can effectively improve intraoperative vital signs and postoperative recovery quality, enhance analgesia and sedation, reduce the dosage of remifentanil hydrochloride for injection and propofol emulsion injection, reduce the incidence of postoperative delirium, regulate the levels of neuronal injury markers and neurotransmitter markers, and has good safety.