Circumferential Spread of Anesthetic and Success in Sciatic Nerve Blockade

Study Overview
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Brief Summary
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Current practices when performing any peripheral nerve block may or may not involve ensuring circumferential spread of local anesthetic around the nerve. Ensuring circumferential spread can involve several redirections of the needle above and below the nerve, and potentially could result in either more discomfort for the patient or an increased chance of inadvertent direct trauma to the nerve. Not ensuring spread around the nerve may result in a slower and less complete blockade. The investigators suspect that by ensuring complete spread around the nerve, the speed of block onset would be quicker because it avoids the loss due to diffusion time.

Official Title
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Does Ensuring Circumferential Local Anesthetic Spread Improve the Success of Ultrasound Guided Sciatic Nerve Block at the Popliteal Fossa?

Conditions
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Sciatic Nerve Blockade for Foot/Ankle Surgery

Intervention / Treatment
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* Procedure: Circumferential spread of local anesthetic
* Procedure: Non-circumferential spread of local anesthetic


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: English-speaking ASA physical status I-III 18-85 years of age, inclusive 50-110 kg, inclusive 150 cm of height or grater Scheduled for elective foot or ankle surgery 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 neurologic disorder affecting the lower extremity Pregnancy Contraindications to, allergies to, and/or past adverse reactions to study medications (local anesthetics, opioid analgesics) History of alcohol or drug dependency/abuse History of long term opioid intake 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>Ensuring circumferential spread of local anesthetic around the sciatic nerve. | Procedure: Circumferential spread of local anesthetic<br>* The anesthetist will ensure, under ultrasound guidance, that local anesthetic (1 mL of 1% lidocaine) surrounds the sciatic nerve.<br>|
| Active Comparator: 2<br>Single shot injection of local anesthetic near the sciatic nerve will be performed, without ensuring circumferential spread. | Procedure: Non-circumferential spread of local anesthetic<br>* The anesthetist will perform a single shot injection of local anesthetic (1 mL of 1% lidocaine) near the sciatic nerve under ultrasound guidance, without ensuring circumferential spread around the nerve.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Onset time of sciatic nerve blockade. |  | Every 5 minutes for 30 minutes after anesthetic injection | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Block success, time required to perform block, complications/adverse events, number of needle passes, patient discomfort |  | 24 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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sciatic nerve block, local anesthetic, lidocaine, ankle surgery, foot surgery, ultrasound-guided regional anesthesia, circumferential spread, anesthetic infiltration