The optimal dose of dexmedetomidine as a 0.59% ropivacaine adjuvant for epidural anesthesia in great saphenous varicose vein surgery, based on hemodynamics and anesthesia efficacy: a randomized, controlled, double-blind clinical trial

Objective: This study aimed to explore the optimal dose of dexmedetomidine as a 0.59% ropivacaine adjuvant for epidural anesthesia on perioperative hemodynamics and anesthesia efficacy in patients undergoing great saphenous varicose vein surgery. Methods: A total of 90 patients were randomly divided into three groups: 0.25 mu g/kg dexmedetomidine combined with 0.59% ropivacaine epidural infusion group (ED1 group), 0.5 mu g/kg dexmedetomidine combined with 0.59% ropivacaine epidural infusion group (ED2 group), and 0.75 mu g/kg dexmedetomidine combined with 0.59% ropivacaine epidural infusion group (ED3 group). Hemodynamics, anesthesia efficiency, and adverse reactions were recorded. Main results: Compared with the ED1 group, the ED2 group had lower systolic blood pressure at T1-3 (T-1, 95%CIs, 6.52-21.93, p < 0.001; T-2, 95%CIs, 2.88-18.21, p = 0.004; T-3, 95%CIs, 0.49-18.17, p = 0.035), and the diastolic blood pressure at T1-2 was decreased (T-1, 95%CIs, 4.55-14.36, p < 0.001; T-2, 95%CIs, 0.37-12.17, p = 0.033). Compared with the ED2 group, the ED3 group had higher systolic blood pressure at T1-2 (T-1, 95%CIs, 5.90-21.46, p < 0.001; T-2, 95%CIs, 2.07-17.55, p = 0.008) and higher diastolic blood pressure at T1-3 (T-1, 95%CIs, 2.91-12.81, p = 0.001; T-2, 95%CIs, 1.32-13.23, p = 0.011; T-3, 95%CIs, 0.14-11.52, p = 0.043). Compared with the ED2 group, the heart rate was significantly decreased at T1-4 in the ED3 group (T-1, 95%CIs, 2.25-15.72, p = 0.005; T-2, 95%CIs, 2.35-13.82, p = 0.003; T-3, 95%CIs, 0.50-9.79, p = 0.025; T-4, 95%CIs, 1.46-10.36, p = 0.005). The myocardial oxygen consumption in all three groups was significantly decreased at each time point compared to T-0 (p < 0.05 or < 0.001), and no significant between-group differences were detected (P>0.05). Compared with the ED1 group, the anesthesia efficiency of ED2 and ED3 groups was markedly enhanced, but the risk of bradycardia in ED2 and ED3 groups was dramatically increased (6 of 28 [21.4%] vs. 14 of 30 [46.7%] and 14 of 27 [51.9%], p = 0.023), one patient in the ED3 group experienced difficulty urinating, and remaining adverse reactions were mild in all three groups. Conclusion: A measure of 0.5 mu g/kg dexmedetomidine is the optimal dose as a 0.59% ropivacaine adjuvant for epidural anesthesia in patients undergoing great saphenous varicose vein surgery.