The Minimum Effective Concentration of Ropivacaine in Ultrasound-guided Supraclavicular Block

Study Overview
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Brief Summary
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The aim of this study is to determine the minimum effective concentration of local anesthetic (ropivacaine 40mL) required to produce an effective double-injection USG-SCB for surgical anesthesia in 90% of patients (MEC90) in young group (18-40 years) and in middle aged group (40-65 years) of patients scheduled for elective surgery of one upper limb distal to the shoulder.

Detailed Description
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The study is based on biased coin design, and the concentration of LA for the next patient is determined by the result of the last one. In the case of block failure, the concentration will be increased by 0.025%. Conversely, block success will result in either a reduction in concentration by 0.025% (probability 11%) or no change in concentration (probability 89%). A blinded assistant will assess sensory and motor blockade in each nerve territory ( the median, radial, ulnar and musculocutaneous nerves) at 10-min intervals up to 30 min after completion of the block. Finally, MEC90 is calculated by isotonic regression.

Official Title
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The Minimum Effective Concentration of Ropivacaine in Ultrasound-guided Supraclavicular Block

Conditions
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Minimum Effective Concentration of Local Anesthetic

Intervention / Treatment
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* Other: brachial plexus block


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age between 18 and 65 years ASA 1-3 body mass index between 18 and 35kg/m2 Exclusion Criteria: inability to consent to the study pregnancy allergy to local anesthetics preexisting neuropathy or coagulopathy prior surgery in the supraclavicular region

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: middle aged group<br>brachial plexus block with ropivacaine 40ml, MEC90 for USG-SCB | Other: brachial plexus block<br>* brachial plexus block with ropivacaine 40ml<br>* Other names: ultrasound guided supraclavicular block;|
| Active Comparator: young group<br>brachial plexus block with ropivacaine 40ml, MEC90 for USG-SCB | Other: brachial plexus block<br>* brachial plexus block with ropivacaine 40ml<br>* Other names: ultrasound guided supraclavicular block;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The Minimum Effective Concentration of Ropivacaine in Ultrasound-guided Supraclavicular Block | The Minimum Effective Concentration (MEC) of Ropivacaine in Ultrasound-guided Supraclavicular Block is based on 60 measurements in 60 patients (secondary outcome measure: block success). MEC is determined by biased coin design method when all patients have been tested in the study. | up to 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Block success | A blinded Assistant assess the sensory and motor block onset time for each nerve (median, radial, ulnar and musculocutaneous) at 10-min intervals up to 30 min after completion of the block. | up to 30 minutes after nerve block is performed | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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ropivacaine, minimum effective concentration, ultrasound-guided supraclavicular block