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Peer-reviewedCC BY 4.0Frontiers in Pharmacology

The median effective dose of hyperbaric ropivacaine and lateral decubitus time for unilateral spinal anesthesia in lower extremity varicose vein surgery: a dose- and time-finding study

  • Jun Xu1,2
  • Jiaying Zhou1
  • Haibo Chen1
  • Chao Lin1,3
  • Wenlin Xian1
  • FangJun Wang1
  1. 1The Affiliated Hospital of North Sichuan Medical College
  2. 2The Integrated Traditional Chinese and Western Medicine Hospital of Liangshan Yi Autonomous Prefecture
  3. 3The People’s Hospital of Yilong County
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Abstract

Background: The aim of this study was to determine the median effective dose (ED50) of 0.5% hyperbaric ropivacaine for motor block in the non-surgical extremity and the median effective lateral decubitus time (ET50) for preventing motor block in the non-surgical extremity during lower extremity varicose vein surgery.

Methods: Sixty patients undergoing unilateral lower extremity varicose vein surgery under combined spinal-epidural anesthesia were enrolled in two sequential phases: a dose-finding phase ( n = 30) and a time-finding phase ( n = 30). All patients received intrathecal 0.5% hyperbaric ropivacaine. A modified Dixon up-and-down method was applied sequentially. In the dose-finding phase, the lateral decubitus position was maintained for 20 min. In the subsequent time-finding phase, patients received the ED5 of hyperbaric ropivacaine estimated in the dose-finding phase, corresponding to a 5% probability of motor block in the non-surgical extremity. Successful prevention of motor block was defined as a modified Bromage score <1. For probit analysis, motor block (modified Bromage score ≥1) was coded as the positive response in the dose-finding phase, whereas successful prevention of motor block in the non-surgical extremity was coded as the positive response in the time-finding phase. The ED50 and ET50 were treated as the primary estimates, whereas additional quantile estimates derived from the fitted probit models were considered exploratory.

Results: The ED50 of 0.5% hyperbaric ropivacaine for motor block in the non-surgical extremity was 12.683 mg (95% CI: 12.367-12.997 mg). The ET50 of lateral decubitus time for preventing motor block in the non-surgical extremity was 13.887 min (95% CI: 13.390-14.338 min). The exploratory ED5, corresponding to a 5% probability of motor block, was 11.956 mg (95% CI, 10.304-12.303 mg), while the exploratory ET95 was 14.957 min (95% CI, 14.455-17.016 min). Adverse events were infrequent, and intraoperative hemodynamics remained stable.

Conclusion: The ED50 of 0.5% hyperbaric ropivacaine for non-surgical extremity was 12.683 mg (95%CI: 12.367-12.997 mg), and the ET50 of lateral decubitus time for preventing motor block was 13.887 min (95% CI: 13.390-14.338 min).

Clinical Trial Registration: [ www.chictr.org.cn/showproj.html?proj=239741 ], identifier [ChiCTR2400088340].

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Cite

BibTeXRIS
BibTeX
@article{xu2026median,
  title = {{The median effective dose of hyperbaric ropivacaine and lateral decubitus time for unilateral spinal anesthesia in lower extremity varicose vein surgery: a dose- and time-finding study}},
  author = {Jun Xu and Jiaying Zhou and Haibo Chen and Chao Lin and Wenlin Xian and FangJun Wang},
  journal = {Frontiers in Pharmacology},
  year = {2026},
  month = oct,
  doi = {10.3389/fphar.2026.1975353},
  url = {https://www.frontiersin.org/articles/10.3389/fphar.2026.1975353/full},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - The median effective dose of hyperbaric ropivacaine and lateral decubitus time for unilateral spinal anesthesia in lower extremity varicose vein surgery: a dose- and time-finding study
AU  - Jun Xu
AU  - Jiaying Zhou
AU  - Haibo Chen
AU  - Chao Lin
AU  - Wenlin Xian
AU  - FangJun Wang
PY  - 2026
DA  - 2026/10/21
JO  - Frontiers in Pharmacology
DO  - 10.3389/fphar.2026.1975353
UR  - https://www.frontiersin.org/articles/10.3389/fphar.2026.1975353/full
AB  - Background: The aim of this study was to determine the median effective dose (ED50) of 0.5% hyperbaric ropivacaine for motor block in the non-surgical extremity and the median effective lateral decubitus time (ET50) for preventing motor block in the non-surgical extremity during lower extremity varicose vein surgery.  Methods: Sixty patients undergoing unilateral lower extremity varicose vein surgery under combined spinal-epidural anesthesia were enrolled in two sequential phases: a dose-finding phase ( n = 30) and a time-finding phase ( n = 30). All patients received intrathecal 0.5% hyperbaric ropivacaine. A modified Dixon up-and-down method was applied sequentially. In the dose-finding phase, the lateral decubitus position was maintained for 20 min. In the subsequent time-finding phase, patients received the ED5 of hyperbaric ropivacaine estimated in the dose-finding phase, corresponding to a 5% probability of motor block in the non-surgical extremity. Successful prevention of motor block was defined as a modified Bromage score <1. For probit analysis, motor block (modified Bromage score ≥1) was coded as the positive response in the dose-finding phase, whereas successful prevention of motor block in the non-surgical extremity was coded as the positive response in the time-finding phase. The ED50 and ET50 were treated as the primary estimates, whereas additional quantile estimates derived from the fitted probit models were considered exploratory.  Results: The ED50 of 0.5% hyperbaric ropivacaine for motor block in the non-surgical extremity was 12.683 mg (95% CI: 12.367-12.997 mg). The ET50 of lateral decubitus time for preventing motor block in the non-surgical extremity was 13.887 min (95% CI: 13.390-14.338 min). The exploratory ED5, corresponding to a 5% probability of motor block, was 11.956 mg (95% CI, 10.304-12.303 mg), while the exploratory ET95 was 14.957 min (95% CI, 14.455-17.016 min). Adverse events were infrequent, and intraoperative hemodynamics remained stable.  Conclusion: The ED50 of 0.5% hyperbaric ropivacaine for non-surgical extremity was 12.683 mg (95%CI: 12.367-12.997 mg), and the ET50 of lateral decubitus time for preventing motor block was 13.887 min (95% CI: 13.390-14.338 min).  Clinical Trial Registration: [ www.chictr.org.cn/showproj.html?proj=239741 ], identifier [ChiCTR2400088340].
SN  - 1663-9812
ER  -