• Xincheng Liao, Jie Lin, Xinru Shu, Shisen Hong, Yusheng Yao, and Hao Li.
• Department of Anesthesiology, Shengli Clinical Medical College of Fujian Medical University, Fujian Provincial Hospital, Fuzhou, China.
• Ann. Med. 2023 Jan 1; 55 (2): 23006632300663.

BackgroundDexmedetomidine enhances the quality and duration of lidocaine intravenous regional anaesthesia (IVRA). However, the two administration routes have not been directly compared regarding effects on tourniquet tolerance time with lidocaine IVRA. Additionally, it remains unclear whether the prolonged tourniquet tolerance stems from the direct peripheral action of dexmedetomidine or indirect systemic analgesic effects.MethodsWe conducted forearm IVRA in 12 healthy volunteers using a crossover design on two separate study days. One day, the systemic dexmedetomidine group received an intravenous infusion of 0.5 μg/kg dexmedetomidine (20 mL) in one arm, followed by 0.5% lidocaine (25 mL) forearm IVRA in the contralateral arm. On the other day, the regional dexmedetomidine group received an intravenous 0.9% saline infusion (20 mL) in one arm, followed by combined 0.5% lidocaine (25 mL) and 0.5 μg/kg dexmedetomidine forearm IVRA in the opposite arm. After a two-week washout period, participants crossed over to receive the alternate treatment. The primary outcome was tourniquet tolerance time, from initiating IVRA until the patient-reported tourniquet pain numerical rating scale exceeded three.ResultsThe tourniquet tolerance time was longer with regional versus systemic dexmedetomidine (36.9 ± 7.6 min vs 23.3 ± 6.2 min, respectively), with a 13.6 min mean difference (95% CI: 10.8 to 16.4 min, p < 0.001). Regional dexmedetomidine also hastened sensory onset and extended sensory recovery compared to systemic administration. Delayed sedation after tourniquet release occurred in 5 of 12 subjects receiving regional dexmedetomidine.ConclusionThe addition of regional dexmedetomidine to lidocaine prolonged tourniquet tolerance time in forearm IVRA to a greater extent compared to systemic dexmedetomidine in healthy volunteers.Trial RegistrationChinese Clinical Trial Registry, ChiCTR2300067978.

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