To explore the efficacy and safty of different administration routes of dexmedetomidine injection in elderly patients undergoing total hip arthroplasty (THA).

The elderly THA patients were randomly divided into the intravenous group (ID group, ropivacaine injection nerve block, 0.5 μg·kg^-1 dexmedetomidine injection administered by intravenous pump) and the perineural group (PD group, 0.5 μg·kg^-1 dexmedetomidine injection combined with ropivacaine injection nerve block). Compare the postoperative visual analog scale (VAS) scores, inflammatory factors, hemodynamic parameters, awakening time, incidence and duration of emergence agitation (EA), mini-mental state examination (MMSE) scores, riker sedation-agitation scale (RSAS), oxidative stress and immune function between the two groups and safty evaluation was conduated.

A total of 102 cases were included, 51 in the ID group and 51 in the PD group. At 48 hours after surgery, the resting VAS scores of ID group and PD group were (1.85±0.73) and (1.52±0.61) points, and the movement VAS scores were (3.61±0.64) and (3.27±0.42) points, respectively. The rest/movement VAS scores of PD group were significantly lower than those of ID group (all P<0.05). Immediately after surgery, C-reactive protein (CRP) in ID group and PD group were (6.80±1.03) and (6.13±0.75) mg·L^-1, interleukin-1β (IL-1β) were (8.06±0.87) and (6.07±0.63) pg·mL^-1, tumor necrosis factor-α (TNF-α) were (99.24±12.03) and (81.10±9.25) ng·mL^-1, interleukin-8 (IL-8) were (8.03±0.73) and (6.19±0.68) pg·mL^-1, interleukin-6 (IL-6) were (39.68±7.25) and (32.35±6.86) pg·mL^-1; 1 day after surgery, CRP in ID group and PD group were (6.07±1.07) and (5.37±0.81) mg·L^-1, IL-1β were (6.71±0.66) and (5.24±0.65) pg·mL^-1, TNF-α were (98.21±11.00) and (77.48±10.78) ng·mL^-1, IL-8 were (6.76±0.57) and (5.29±0.60) pg·mL^-1, IL-6 were (37.93±8.65) and (30.34±7.20) pg·mL^-1; 3 day after surgery, CRP in ID group and PD group were (5.53±1.04) and (5.06±0.64) mg·L^-1, IL-1β were (6.11±0.73) and (4.30±0.68) pg·mL^-1, TNF-α were (83.97±13.78) and (51.32±9.69) ng·mL^-1, IL-8 were (6.26±0.67) and (4.33±0.52) pg·mL^-1, IL-6 were (31.35±7.06) and (28.24±5.23) pg·mL^-1. The levels of CRP, IL-1β, TNF-α, IL-8 and IL-6 in PD group were statistically significantly lower than those in ID group immediately after operation, 1 day and 3 days after operation (all P<0.05). The recovery time of ID group and PD group was (28.93±3.00) and (25.93±2.91) min, respectively; the incidence of EA was 23.53% and 7.84%, respectively; the duration of EA was (2.32±0.38) and (1.82±0.36) days, respectively. Immediately after surgery, superoxide dismu-tase (SOD) in ID group and PD group were (136.47±16.96) and (154.81±15.38) U·mL^-1, malondialdehyde (MDA) were (8.89±1.24) and (6.54±1.13) nmol·mL ^-1, CD4⁺ were (29.28±2.94)% and (32.62±2.57)%, CD4⁺/CD8⁺ were (1.34±0.39)% and (1.55±0.37)%; 1 day after surgery, SOD in ID group and PD group were (149.82±17.54) and (157.73±16.52) U·mL^-1, MDA were (6.04±1.10) and (4.37±1.02) nmol·mL ^-1, CD4⁺ were (24.75±1.71)% and (28.36±2.31)%, CD4⁺/CD8⁺ were (1.24±0.31)% and (1.37±0.33)%; 3 day after surgery, SOD in ID group and PD group were (156.44±19.73) and (164.39±19.15) U·mL^-1, MDA were (5.27±0.95) and (4.05±0.68) nmol·mL ^-1, CD4⁺ were (27.35±1.78)% and (31.16±2.33)%, CD4⁺/CD8⁺ were (1.22±0.35)% and (1.43±0.40)%. SOD、CD4⁺、CD4⁺/CD8⁺ in PD group were statistically significantly higher than those in ID group (all P<0.05), MDA was statistically significantly lower than that in ID group (P<0.05). Among the routes of administration, ID was a risk factor for EA during general anesthesia in THA in elderly patients (P<0.05). Among the administration doses, different administration doses did not increase the risk of EA during general anesthesia in elderly patients with THA (P>0.05).

Compared with intravenous administration, peripheral dexmedetomidine injection can effectively reduce the incidence of EA, reduce inflammation and oxidative stress, improve analgesia and immune function in elderly patients with THA, and the effect can be achieved at a lower dose, which is recommended as the preferred anesthesia auxiliary scheme.