Ultrasound Guided Distal Sciatic Nerve Block - a Comparison With Nerve Stimulator Technique

Study Overview
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Brief Summary
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For distal sciatic nerve block this prospective, randomised comparison with ultrasound guided distal subepineural block tested the hypothesis, that intraepineural injection of local anesthetic using nerve stimulation technique is common and associated with high success rate.

Detailed Description
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Classical methods for nerve localization (loss of resistance, cause of paresthesias, nerve stimulation technique)assumed that the target is a close approximation to the nerve, without epineural perforation. Intraneural injections were considered as evitable, with high risk for nerve damages. Ultrasound guidance provided for the first time a real-time visualization of the spread of local anesthetic. Some recent studies proved, that an intraneural injection using nerve stimulator technique is common and not necessarily accompanied with nerve damages. In the ultrasound group (group US) the investigators tested the hypothesis, that an intraneural injection of local anesthetic generate a high success rate and a short onset time without clinical apparent nerve damages. In the nerve-stimulation group (group NS) the investigators tested the hypothesis, that an intraneural injection of local anesthetic is common, and in case of intraneural injection accompanied likewise with high success rate and shorter onset time. For the sciatic division the investigators tested the hypothesis, that classical methods of nerve localization (nerve-stimulation technique, cause of paresthesias) are not able to avoid epineural perforation.

Official Title
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Ultrasound Guided Distal Sciatic Nerve Block - a Randomised Comparison With Nerve Stimulator Technique

Conditions
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Other Surgical Procedures

Intervention / Treatment
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* Drug: midazolam
* Drug: Prilocaine 1%
* Drug: Ropivacaine 0.75%
* Drug: Prilocaine 1%
* Device: ultrasound guidance
* Device: nerve stimulation technique


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: elective surgery on the foot or ankle tourniquet distal of the knee adult patients, 18-75 years old ASA-risk-groups I-III (American Society of Anesthesiologists) informed consent Exclusion Criteria: severe coagulopathy systemic inflammatory response ASA-risk-groups > III (American Society of Anesthesiologists) drug allergy: local anesthetics pregnancy, lactation period participation in other studies addiction to drugs or alcohol non-cooperative patients

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 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: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: group US<br>Ultrasound guided block : 20ml Prilocaine 1% and 10ml Ropivacaine 0.75% (30ml Prilocaine 1% in outpatients) | Drug: midazolam<br>* Prior to performing the regional anesthesia the investigators administered midazolam as a premedication by mouth (3,75-7,5mg) or intravenously (2-3mg).<br>* Other names: Dormicum;Drug: Prilocaine 1%<br>* 20ml Prilocaine 1% for distal sciatic nerve block (30ml Prilocaine 1% in outpatients)<br>* Other names: Xylonest;Drug: Ropivacaine 0.75%<br>* 10ml Ropivacaine 0.75% for distal sciatic nerve block (not in outpatients)<br>* Other names: Naropin;Drug: Prilocaine 1%<br>* 10ml Prilocaine 1% for saphenous nerve block<br>* Other names: Xylonest;Device: ultrasound guidance<br>* In group US the sciatic nerve localization and needle guidance is realized using ultrasound.<br>|
| Active Comparator: group NS<br>Nerve stimulation technique: 20ml Prilocaine 1% and 10ml Ropivacaine 0.75% (30ml Prilocaine 1% in outpatients) | Drug: midazolam<br>* Prior to performing the regional anesthesia the investigators administered midazolam as a premedication by mouth (3,75-7,5mg) or intravenously (2-3mg).<br>* Other names: Dormicum;Drug: Prilocaine 1%<br>* 20ml Prilocaine 1% for distal sciatic nerve block (30ml Prilocaine 1% in outpatients)<br>* Other names: Xylonest;Drug: Ropivacaine 0.75%<br>* 10ml Ropivacaine 0.75% for distal sciatic nerve block (not in outpatients)<br>* Other names: Naropin;Drug: Prilocaine 1%<br>* 10ml Prilocaine 1% for saphenous nerve block<br>* Other names: Xylonest;Device: nerve stimulation technique<br>* In the group NS sciatic nerve localization and needle guidance is realized using nerve stimulation technique. However, ultrasound is used observing (Observer) the procedure, but blinded for the physician (Anesthetist) performing the block.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Success Rate Without Supplementation | After injection of local anesthetic a waiting period of 30-60 minutes was defined before completing a failed block. success without supplementation = no additional analgetics or rescue blocks required (success rate without supplementation, outcome measure 1) success with supplementation = analgetics or selective rescue blocks distal of the sciatic division required (success rate without supplementation and additionally all supplemented blocks, outcome measure 3) failed block = change of anesthetic procedure (general, spinal) or rescue blocks proximal of the sciatic division | within 30-60 minutes after injection of the local anesthetic | 
| Time Until Readiness for Surgery (Minutes) |  | within 60 minutes after injection of the local anesthetic | 
| Success Rate With Supplementation | After injection of local anesthetic a waiting period of 30-60 minutes was defined before completing a failed block. success without supplementation = no additional analgetics or rescue blocks required (success rate without supplementation, outcome measure 1) success with supplementation = analgetics or selective rescue blocks distal of the sciatic division required (success rate without supplementation and additionally all supplemented blocks, outcome measure 3) failed block = change of anesthetic procedure (general, spinal) or rescue blocks proximal of the sciatic divisionSucces rate with supplementation | later than 30-60 minutes after injection of the local anesthetic | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Sciatic Nerve, Ultrasound, Anesthesia, Regional, Orthopedic Surgery