{
  "abstract": "Please confirm that an ethics committee approval has been applied for or granted: Yes: I’m uploading the Ethics Committee Approval as a PDF file with this abstract submissionBackground and Aims Bioimpedance refers to the resistance of biological tissues to electrical current. It has the potential to enhance the accuracy of peripheral nerve blocks by providing real-time feedback during regional anesthesia, complementing ultrasound and nerve stimulation techniques. This study assesses impedance variations during axillary peripheral nerve block. Understanding how impedance varies across different tissue types can help guide precise needle placement for block success, reducing complications such as intraneural or intravascular injections.Methods This prospective exploratory observational study included patients undergoing axillary nerve block for upper limb surgical procedures. Before the procedure, patients received 50µg of fentanyl and 1 mg of midazolam, with continuous standard monitoring. An anesthesiologist performed nerve block under ultrasound guidance using nerve stimulation in sentinel mode (0.1 ms, 0.5 mA, 2 Hz) with nerve stimulator device which continuously displayed electrical impedance. An assistant administered the local anesthetic, while another, blinded to the procedure, recorded impedance values across subcutaneous tissue, muscle, fascia, and nerves. A linear mixed model was performed to assess impedance across tissue types, using tissue type as a fixed effect and subject-level random effects to account for variability, with random slopes that captured within-subject variation. Statistical analysis was conducted using STATA-18.Results Among 74 participants (mean age: 54), impedance (kΩ) was recorded across tissue types: subcutaneous (5.2–18.7), muscle (5.3–17.7), fascia (4.7–17.7), radial nerve (4.2–11.8), and median nerve (3.7–11.5). A clear decrease in impedance was observed from subcutaneous tissue to median nerve. Bonferroni-corrected pairwise comparisons showed significant differences (p<0.05) between various tissue types and nerves. A borderline difference appeared between fascia and the median nerve. No complications (intraneural/intravascular injections) were detected.Abstract P187 Figure 1Bioimpedance across different tissue types during axillary nerve blockConclusions The observed trend demonstrates a consistent reduction in impedance values as the needle advances toward the target nerves. Incorporating impedance monitoring may improve nerve block accuracy by serving as an additional parameter for guiding needle placement through different tissue layers.",
  "authors": [
    {
      "affiliations": [
        "Anesthesiology, Lebanese American University/Lebanese American University Medical Center – Rizk Hospital, Beirut, Lebanon"
      ],
      "name": "Georges Assaf"
    },
    {
      "affiliations": [
        "Anesthesiology, Lebanese American University/Lebanese American University Medical Center – Rizk Hospital, Beirut, Lebanon"
      ],
      "name": "Chahd Mazyan"
    },
    {
      "affiliations": [
        "Anesthesiology, Lebanese American University/Lebanese American University Medical Center – Rizk Hospital, Beirut, Lebanon"
      ],
      "name": "Michel Akiki"
    },
    {
      "affiliations": [
        "Anesthesiology, Lebanese American University/Lebanese American University Medical Center – Rizk Hospital, Beirut, Lebanon"
      ],
      "name": "Rony Al Nawar"
    },
    {
      "affiliations": [
        "Anesthesiology, Lebanese American University/Lebanese American University Medical Center – Rizk Hospital, Beirut, Lebanon"
      ],
      "name": "Vanda Yazbeck-Karam"
    },
    {
      "affiliations": [
        "Anesthesiology, Lebanese American University/Lebanese American University Medical Center – Rizk Hospital, Beirut, Lebanon"
      ],
      "name": "Hanane Barakat"
    }
  ],
  "title": "P187 Assessing the enhanced precision: the value of impedance in ultrasound-guided nerve blocks, an exploratory prospective observational study",
  "uid": "546afbf9-4ec5-55cd-b58f-2be052e4a7b2"
}