Efficacy of Ultrasound-Guided Local Anesthetic Injection Into or Around the Sciatic Nerve for Lower Limb Anesthesia

Study Overview
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Brief Summary
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This study was designed to assess whether the injection of local anesthetic into the nerve (intraneural), as opposed to around it (perineural), requires a shorter time to develop surgical anesthesia of the lower leg. The investigators will compare the two types of injection using the same drug, so as to determine if there is an actual difference onset time. They will also examine the overall success rate of either kind of sciatic nerve blocks as the sole anesthetic for non-emergent orthopedic surgery. The safety of these procedures will be examined by in-hospital and phone-call follow-up contacts.

Detailed Description
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This will be a randomized, controlled, patient- and observer-blinded trial assessing block characteristics after intra- or perineural injection of ropivacaine for subgluteal sciatic nerve blocks performed for elective surgery of the lower limb.

Official Title
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Intraneural Injection of Ropivacaine for Subgluteal Sciatic Nerve Block Leads to Faster Onset and Higher Success Rates: a Randomized, Controlled Trial

Conditions
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Orthopedic Disorders, Foot Diseases, Injuries, Leg, Injuries, Foot, Injuries, Knee

Intervention / Treatment
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* Procedure: Intraneural Injection for Subgluteal Sciatic Nerve Block
* Procedure: Perineural Injection for Subgluteal Sciatic Nerve Block
* Procedure: Femoral Nerve Block
* Procedure: Patient-Controlled Postoperative Analgesia
* Drug: Ropivacaine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Undergoing non-emergent orthopedic procedure of knee, leg, foot with thigh tourniquet ASA Physical Status Class I-III Consenting to surgery under peripheral nerve block anesthesia (sciatic + femoral/saphenous block) Exclusion Criteria: Unable to understand or communicate for the purpose of the study Exhibiting any neurological disturbance of the ipsilateral lower extremity Inability to satisfactorily image the sciatic nerve in the opinion of the attending anesthesiologist

Ages Eligible for Study
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Minimum Age: 18 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: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Perineural<br>Patients in this group will receive a perineural injection for subgluteal sciatic nerve block under real-time, short-axis, in-plane ultrasound guidance, in addition to a femoral nerve block and patient-controlled postoperative analgesia. Ropivacaine will be used for the sciatic nerve block, whereas the choice of agent for the femoral nerve block is left to the attending anesthesiologist. | Procedure: Perineural Injection for Subgluteal Sciatic Nerve Block<br>* The injection will start as the needle indents the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as intraneural if the drug infiltrates the space between the epimysium of the surrounding muscles and the outer epineurium of the sciatic nerve. Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach.<br>* Other names: Injection outside the paraneurium;Procedure: Femoral Nerve Block<br>* Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated.<br>Procedure: Patient-Controlled Postoperative Analgesia<br>* Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication.<br>* Other names: Patient-controlled continuous peripheral nerve block;Drug: Ropivacaine<br>* Thirty milliliters of 0.75% (wt/vol) ropivacaine will be used for the sciatic nerve block.<br>* Other names: Naropine;|
| Experimental: Intraneural<br>Patients in this group will receive an intraneural injection for subgluteal sciatic nerve block under real-time, short-axis, in-plane ultrasound guidance, in addition to a femoral nerve block and patient-controlled postoperative analgesia. Ropivacaine will be used for the sciatic nerve block, whereas the choice of agent for the femoral nerve block is left to the attending anesthesiologist. | Procedure: Intraneural Injection for Subgluteal Sciatic Nerve Block<br>* The injection will start as the needle penetrates the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as intraneural if nerve cross section expansion and a reduction in echogenicity are observed. Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach.<br>* Other names: Subparaneural injection;Procedure: Femoral Nerve Block<br>* Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated.<br>Procedure: Patient-Controlled Postoperative Analgesia<br>* Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication.<br>* Other names: Patient-controlled continuous peripheral nerve block;Drug: Ropivacaine<br>* Thirty milliliters of 0.75% (wt/vol) ropivacaine will be used for the sciatic nerve block.<br>* Other names: Naropine;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Onset Time of Sciatic Nerve Block | Time to onset of sciatic nerve anesthesia, defined as both following criteria: Sensory: does not feel pain or discomfort when pricked with a 25G needle. Motor: able to slightly curl toes; unable to flex the ankle. | ≤30 minutes after block performance | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Success Rate of Sciatic Nerve Blocks | The percentage of patients who attain the criteria for block success within 30 minutes of the injection. Investigators will also report the percentage of patients who successfully complete surgery without significant additional analgesia (see below); this will be defined as clinical success rate. | ≤30 min after block performance | 
| Incidence and Prevalence of Neurologic Disturbances | Patients will be interviewed at  4 h (block resolution visit), 7 days and (if necessary) at 30 days to assess for residual neurologic disturbances in the sciatic nerve territory. The incidence/prevalence of these phenomena will be noted. | 30 days after anesthesia performance | 
| Differences in Time to Resolution of Sciatic Nerve Block | The time at which sensory and motor function of the sciatic nerve have recovered at least to the following criteria: Sensory: patients feel discomfort when pricked with a thin needle (25G) Motor: patients may move both toes and ankle, albeit with reduced strength This outcome measure will be examined by an investigator every 30-60 min and reported by patients as time to return of sensation and movement. The investigator-reported value will be preferred if both are available. | <12 h | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Sciatic Nerve, Lower Extremity, Anesthetics, Local, Ropivacaine, Ultrasonography