Does Interneural Local Anesthetic Spread at the Site of Sciatic Nerve Bifurcation Shorten Block Onset Time?

Study Overview
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Brief Summary
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Following foot and ankle surgery, ultrasound-guided sciatic nerve block (SNB) at the popliteal fossa decreases post-operative pain and opioid consumption. At the popliteal fossa, the sciatic nerve bifurcates to form the Common Peroneal Nerve (CPN) and Tibial Nerve (TN). Studies have shown that when both branches are blocked separately distal to the bifurcation site, block onset time is reduced by 30%. Through clinical observation, the investigators found that onset time is further shortened when ultrasound-guided SNB is performed at the site of bifurcation. This is because the local anesthetic spreads interneurally. The purpose of this study is to compare the block onset time of an ultrasound-guided sciatic nerve block at the site of nerve bifurcation with the blockade of each terminal nerve separately (TN and CPN) distal to sciatic nerve bifurcation.

Official Title
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Does Interneural Local Anesthetic Spread at the Site of Sciatic Nerve Bifurcation Shorten Block Onset Time?

Conditions
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Post Operative Analgesia, Regional Anesthesia, Sciatic Nerve Block

Intervention / Treatment
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* Procedure: Distal
* Procedure: Interneural


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA physical status I-III 18-85 years of age, inclusive 50-120 kg, inclusive 150 cm of height or greater Exclusion Criteria: Contraindications to sciatic nerve block (e.g., allergy to local anesthetics, coagulopathy, malignancy or infection in the popliteal area) Significant peripheral neuropathy or neurological disorder affecting the lower extremity Pregnancy History of alcohol or drug dependency/abuse History of significant psychiatric conditions that may affect patient assessment

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Distal<br>Blockade of both terminal branches of Sciatic nerve separately, distal to bifurcation | Procedure: Distal<br>* Blockade of both terminal branches of Sciatic nerve separately, distal to bifurcation<br>|
| Active Comparator: Interneural<br>sciatic nerve blockade at the site of bifurcation | Procedure: Interneural<br>* Sciatic nerve blockade at the site of bifurcation<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Block onset Time | We aim to compare the block onset time of an ultrasound-guided sciatic nerve block at the site of nerve bifurcation resulting in interneural spread of local anesthetic with that of blockade of each terminal nerve separately (TN and CPN), distal to sciatic nerve bifurcation. We hypothesize that sciatic nerve blockade at the site of bifurcation with interneural local anesthetic spread within a common epineural sheath results in shorter onset time compared to blockade of each terminal nerve distal to sciatic nerve bifurcation. | every 5 minutes up to 45 minutes of the block or until surgery starts | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Extent of longitudinal local anesthetic solution spread |  | starting at block administration till 5 minutes after complete injection | 
| Nerve diameter prior to and following injection |  | starting at block administration till 5 minutes after complete injection | 
| Block procedure time |  | starting at block administration till complete injection(up to 10 minutes) | 
| Number of skin punctures required. |  | starting at first attempt of block administration till complete injection(up to 10 minutes) | 
| Block success rate |  | starting after complete injection up to 45 minutes | 
| Incidence of block-related complications | Incidence of block-related complications (vascular puncture, hematoma formation, intravascular injection and post-operative neurologic deficit) will be documented, but due to the very low incidence in all block-related complications, this study is not powered to show a difference in safety | immediately , at 24 hours and Post operative day 7 | 
| Postoperative pain | Postoperative pain: Postoperative pain using a verbal rating score (0-10, where 0= no pain, 10=excruciating pain) at 0, 30, 60, 90 and 120 min upon admission to post-anesthetic care unit. | starting at patient's arrival at post-anesthetic care unit till 120 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Regional anesthesia, Sciatic nerve block, foot surgery, ankle surgery, Interneural local anesthetic