The Use of Bupivacaine and Ropivacaine for Sciatic Nerve Block

Study Overview
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Brief Summary
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The duration of motor block for infragluteal parabiceps sciatic nerve block following total knee replacement may vary between 12-36 hrs depending on the amount of local anesthetic given.

Official Title
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A Dose Response Study for Duration of Analgesia Using Bupivacaine and Ropivacaine for Infragluteal Parabiceps Sciatic Block

Conditions
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The Duration of Motor Block May Vary Between 12-36 Hrs

Intervention / Treatment
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* Drug: Bupivacaine
* Drug: Ropivacaine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients (>18 years of age) who are undergoing elective total knee arthroplasty will be included in the study. Exclusion Criteria: Exclusion criteria for the study are patient refusal to be included in the study, contraindications to regional anesthesia, history of allergy to amide local anesthetics, the presence of a progressive neurological deficit, the presence of coagulopathy or infection, or pregnancy

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: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Bupivacaine<br>Varying does to determine duration of analgesia following a sciatic nerve block | Drug: Bupivacaine<br>* Varying doses to determine the duration of analgesia<br>|
| Active Comparator: Ropivacaine<br>Varying does to determine duration of analgesia following a sciatic nerve block | Drug: Ropivacaine<br>* Varying doses to determine the duration of analgesia<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Duration of Motor and Sensory Block of the Sciatic With 0.5% Bupivacaine and Ropivacaine After Ultrasound-guided Nerve-stimulator-Assisted Needle Positioning Beneath the CIEL | Subject reported and investigator measured motor and sensory blockade of the sciatic nerve with less than 10ml of 0.5% bupivacaine and ropivacaine after ultrasound-guided nerve-stimulator-assisted needle positioning beneath the common investing external layer (CIEL). | 3 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cumulative Probabilities for Needle Positioning Above and Below CIEL. | The cumulative probability distributions for the minimal current to evoke a motor response with the needle tip positioned external (above) to the common investing extraneural layer (CIEL) and the cumulative probability distribution for the needle tip postioned internal (below) to the CIEL were sought. The difference in the mean minimum threshold current (mA) for the external (above) and internal (below) CIEL positioning were calculated. | 1 Day |