{
  "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.\n\nMethods: 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.\n\nResults: 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.\n\nConclusion: 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).\n\nClinical Trial Registration: [ www.chictr.org.cn/showproj.html?proj=239741 ], identifier [ChiCTR2400088340].",
  "abstract_shown": true,
  "affiliations": [
    "The Affiliated Hospital of North Sichuan Medical College",
    "The Integrated Traditional Chinese and Western Medicine Hospital of Liangshan Yi Autonomous Prefecture",
    "The People’s Hospital of Yilong County"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Jun Xu"
    },
    {
      "affs": [
        0
      ],
      "name": "Jiaying Zhou"
    },
    {
      "affs": [
        0
      ],
      "name": "Haibo Chen"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Chao Lin"
    },
    {
      "affs": [
        0
      ],
      "name": "Wenlin Xian"
    },
    {
      "affs": [
        0
      ],
      "name": "FangJun Wang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/crp01nt940ese.bib",
  "cited_by": 0,
  "doi": "10.3389/fphar.2026.1975353",
  "fulltext_url": null,
  "id": "crp01nt940ese",
  "issns": [
    "1663-9812"
  ],
  "landing_url": "https://www.frontiersin.org/articles/10.3389/fphar.2026.1975353/full",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2746|Anesthesia and Pain Management"
    ]
  ],
  "openalex": "W7223114482",
  "pdf_url": "https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2026.1975353/pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": "Frontiers Media SA",
  "ris": "https://research.draconitic.com/paper/crp01nt940ese.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:06Z",
      "native_id": "10.3389/fphar.2026.1975353",
      "source": "crossref",
      "url": "https://www.frontiersin.org/articles/10.3389/fphar.2026.1975353/full"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2746|Anesthesia and Pain Management",
      "subfield": "surgery"
    }
  ],
  "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",
  "title_text": "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",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:20:06Z",
  "url": "https://research.draconitic.com/paper/crp01nt940ese",
  "venue": "Frontiers in Pharmacology",
  "versions": []
}