Effects of an Ultrasound‑Guided Femoral, Sciatic, and Genitofemoral Nerve Block with Ropivacaine on EC5 0 and EC9 5 for High Saphenous Vein Ligation.

PURPOSE: To determine the effective concentrations (EC5 0 and EC9 5) of ropivacaine for an ultrasound-guided triple nerve block (femoral(FNB), suprapopliteal sciatic(SPSB), and genitofemoral nerve femoral branch(GFNfB)) in patients undergoing high saphenous vein ligation and stripping.

METHODS

Thirty-six patients scheduled for elective unilateral high saphenous vein ligation and stripping were enrolled. Nerve blocks were performed under ultrasound guidance. The effective concentration of ropivacaine was determined using the Dixon-Massey up-and-down sequential allocation method (initial concentration: 0.25%; step size: 0.01%). EC5 0 and EC9 5 with 95% confidence intervals (CIs) were calculated using probit analysis. Hemodynamic parameters (systolic blood pressure(SBP), diastolic blood pressure(DBP), heart rate (HR)) were recorded at four time points. Pain intensity (visual analog scale, VAS) and motor block (modified Bromage score) were assessed at skin incision. Postoperative complications were recorded.

RESULTS

Relative to baseline, hemodynamic parameters showed small but statistically significant decreases at 15 and 30 minutes after block (all P < 0.05), remaining within clinically acceptable limits. At skin incision, the VAS score in the Success group (n = 23) was significantly lower than in the Failure group (n = 13) [median (IQR), 1 (0, 2) vs 5 (4, 5); z = -5.000, P < 0.001], and the modified Bromage score was significantly higher [1 (0, 1) vs 0 (0, 0); z = -3.062, P = 0.002]. The EC5 0 of ropivacaine was 0.149% (95% CI, 0.118-0.165%) and the EC9 5 was 0.210% (95% CI, 0.181-0.509%). No patient experienced local anesthetic systemic toxicity or other complications.

CONCLUSION

This ultrasound-guided triple nerve block regimen is safe and effective for high saphenous vein ligation. The EC5 0 and EC9 5 of ropivacaine were 0.149% and 0.210%, respectively. An initial concentration of approximately 0.22% is suggested, with subsequent adjustment guided by individual response.