Intravenous lidocaine reduces pain intensity and attenuates the increase in plasma norepinephrine levels after hysterectomy.

Background: Intravenous lidocaine is used to treat acute postoperative pain by reducing discomfort, accelerating mobilization, and shortening hospitalization. This study evaluated the effects of intravenous bolus and continuous lidocaine infusion on pain intensity, fentanyl requirements, and plasma norepinephrine levels in hysterectomy surgery under spinal anesthesia.

Methods: A double-blinded randomized clinical trial was conducted on 46 patients undergoing hysterectomy with spinal anesthesia. The lidocaine group (n = 23) received a 2% lidocaine bolus (1.5 mg/kg) followed by a continuous infusion (1 mg/kg/hour) for 24 hours. The control group (n = 23) received 0.9% NaCl. Resting and moving numeric rating scale (NRS) pain scores, total fentanyl requirements, and norepinephrine levels were recorded at 4, 6, 12, and 24 hours postoperatively.

Results: Statistically significant differences in resting pain NRS were observed at the 4th, 6th, 12th, and 24th hours (0.52 ± 0.51 vs. 1.52 ± 0.51, 0.61 ± 0.58 vs. 1.52 ± 0.51, 0.52 ± 0.51 vs. 1.74 ± 0.81, and 0.52 ± 0.51 vs. 1.52 ± 0.51, respectively; p < 0.001). The reduction in pain score on the moving NRS in the lidocaine group was significantly greater at 6 hours (2.22 ± 0.79 vs. 2.91 ± 1.04; p = 0.001) and 12 hours (2.26 ± 0.75 vs. 2.57 ± 1.12; p < 0.001) postoperatively compared to the control group. Total fentanyl requirements were significantly lower in the lidocaine group (103.04 ± 33.63 mcg vs. 421.74 ± 74.32 mcg; p < 0.001). Plasma norepinephrine changes differed significantly at T6-T0 (-0.66 ± 1.81 pg/mL vs. 1.98 ± 1.69 pg/mL; p < 0.001) and T24-T0 (-1.74 ± 1.94 pg/mL vs. 1.53 ± 1.12 pg/mL; p < 0.001). No side effects were observed.

Conclusion: Intravenous bolus and continuous lidocaine infusion reduced postoperative pain intensity, fentanyl requirements, and norepinephrine levels without significant side effects.