Circumferential Spread of Anesthetic and Success in Sciatic Nerve Blockade

University Health Network, Toronto64 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Sciatic Nerve Blockade for Foot/Ankle Surgery

Interventions

Non-circumferential spread of local anestheticPROCEDURE

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.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 85 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. English-speaking 2. ASA physical status I-III 3. 18-85 years of age, inclusive 4. 50-110 kg, inclusive 5. 150 cm of height or grater 6. Scheduled for elective foot or ankle surgery Exclusion Criteria: 1. Contraindications to sciatic nerve block (e.g., allergy to local anesthetics, coagulopathy, malignancy or infection in the popliteal area) 2. Significant peripheral neuropathy or neurologic disorder affecting the lower extremity 3. Pregnancy 4. Contraindications to, allergies to, and/or past adverse reactions to study medications (local anesthetics, opioid analgesics) 5. History of alcohol or drug dependency/abuse 6. History of long term opioid intake 7. History of significant psychiatric conditions that may affect patient assessment

Outcomes

Primary Outcomes

Onset time of sciatic nerve blockade.

Time frame: Every 5 minutes for 30 minutes after anesthetic injection

Secondary Outcomes

Block success, time required to perform block, complications/adverse events, number of needle passes, patient discomfort

Time frame: 24 hours