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

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

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.

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.

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.

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.

Maintain the same concentration of ropivacaine used in the previous participant with an 89% chance through a random assignment

Decrease the ropivacaine concentration by 0.05% from the concentration used in the previous participant

Decrease ropivacaine concentration by 0.05% from the concentration used in the previous participant with an 11% chance through a random assignment

Increase the ropivacaine concentration by 0.05% from the concentration used in the previous participant

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.

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.

Block duration is the time from when block is performed until the patient first complained of pain at the surgical site post-operatively.

Time to first rescue analgesia is the time from when block is performed until the patient first requested of rescue analgesics post-operatively.

Unintentional nerve damage that occurs during nerve block, pain, bleeding, infection, hypoxia, hypotension

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