Dose-finding Study: Popliteal Sciatic Nerve Block in Patients Undergoing Diabetic Foot Surgery

Study Overview
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Brief Summary
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The purpose of this study was to determine the minimum effective dose of a local anesthetic for proper anesthesia for popliteal sciatic nerve block under ultrasound guidance in patients undergoing surgery for diabetic foot disease.

Detailed Description
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Unlike general patients, patients with diabetic foot disease often have diabetic neuropathy and thus have increased sensitivity to local anesthetics. Therefore, when performing sciatic nerve block, it is essential to properly adjust the dose to prevent neurotoxicity and delay in recovery due to local anesthetics. If the appropriate effective dose of local anesthetic for sciatic nerve block is found in patients with diabetic foot through this study, it is expected that it will be a useful basis for establishing a safe anesthetic method in the case of diabetic foot surgery.

Official Title
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Median Effective Concentration of Ropivacaine for Ultrasound-guided Popliteal Sciatic Nerve Block in Patients Undergoing Diabetic Foot Surgery

Conditions
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Diabetic Foot, Diabetic Neuropathies

Intervention / Treatment
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* Other: Maintain the concentration of ropivacaine as same as those used in the previous participant
* Other: Decrease the ropivacaine concentration by 0.05% from the concentration used in the previous participant
* Other: Increase the ropivacaine concentration by 0.05% from the concentration used in the previous participant


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients who can be operated under popliteal sciatic nerve block among patients undergoing surgery for diabetic foot disease Exclusion Criteria: Infection of the popliteal region Severe coagulation abnormality Allergic reaction or hypersensitivity to local anesthetics Neurological abnormalities other than diabetic neuropathy in the lower extremity of the operation site When it is impossible to evaluate sensory blockage and motor blockage When the patient refuses

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 80 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: Sequential Assignment
Interventional Model Description: The biased coin design up-and-down method
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Sciatic nerve block using same or decreased concentration of local anesthetic<br>If the sciatic nerve block in the previous participant was successful, the concentration of local anesthetic would be maintained or decreased 0.05% in the next patient based on a random assignment. | Other: Maintain the concentration of ropivacaine as same as those used in the previous participant<br>* Maintain the same concentration of ropivacaine used in the previous participant with an 89% chance through a random assignment<br>Other: Decrease the ropivacaine concentration by 0.05% from the concentration used in the previous participant<br>* Decrease ropivacaine concentration by 0.05% from the concentration used in the previous participant with an 11% chance through a random assignment<br>|
| Other: Sciatic nerve block using increased concentration of local anesthetic<br>If the sciatic nerve block in the previous participant was not successful, the concentration of local anesthetic would be increased 0.05% in the next patient. | Other: Increase the ropivacaine concentration by 0.05% from the concentration used in the previous participant<br>* Increase ropivacaine concentration by 0.05% from the concentration used in the previous participant.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Median effective anesthetic concentration 90 (MEAC 90) | Concentration of ropivacaine required for successful sciatic nerve block in 90% of all patients | within 30 minutes from the popliteal sciatic block | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Median effective anesthetic concentration 50 (MEAC 50) | Concentration of ropivacaine required for successful sciatic nerve block in 50% of all patients | within 30 minutes from the popliteal sciatic block | 
| Sensory block onset time | Check for sensory blockade every 5 minutes until 30 minutes after block performed. For sensory block, cold sense using alcohol swabs is evaluated on the foot, comparing with the opposite foot, on a 3-point scale (0 points if there is no cold sense at all, 1 point if there is a decrease, 2 points if it is the same with the opposite foot). The time it takes to block to 0 point is the sensory blockade onset time. | within 30 minutes from the popliteal sciatic block | 
| Motor block onset time | Check for motor blockade every 5 minutes until 30 minutes after block performed. Dorsiflexion and plantar flexion is evaluated, compared to the opposite foot, on a 3-point scale (0 points for inability to move 1 point for reduced movement 2 points for normal movement). The time it takes to block to 0 point is the motor blockade onset time. | within 30 minutes from the popliteal sciatic block | 
| Block duration | Block duration is the time from when block is performed until the patient first complained of pain at the surgical site post-operatively. | within 24 hours post-operatively | 
| Time to first rescue analgesia | Time to first rescue analgesia is the time from when block is performed until the patient first requested of rescue analgesics post-operatively. | within 24 hours post-operatively | 
| Any adverse events | Unintentional nerve damage that occurs during nerve block, pain, bleeding, infection, hypoxia, hypotension | within 24 hours post-operatively |