Conditions: Other Surgical Procedures
Keywords: Sciatic Nerve Ultrasound Anesthesia, Regional Orthopedic Surgery
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 250
Healthy volunteers: no

Brief summary:
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:
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.

Arms:
arm 1: Ultrasound guided block :

20ml Prilocaine 1% and 10ml Ropivacaine 0.75% (30ml Prilocaine 1% in outpatients) arm 2: Nerve stimulation technique:

20ml Prilocaine 1% and 10ml Ropivacaine 0.75% (30ml Prilocaine 1% in outpatients)

Interventions: intervention 1: midazolam intervention 2: Prilocaine 1% intervention 3: Ropivacaine 0.75% intervention 4: Prilocaine 1% intervention 5: ultrasound guidance intervention 6: nerve stimulation technique
Intervention descriptions: intervention 1: Prior to performing the regional anesthesia the investigators administered midazolam as a premedication by mouth (3,75-7,5mg) or intravenously (2-3mg). intervention 2: 20ml Prilocaine 1% for distal sciatic nerve block (30ml Prilocaine 1% in outpatients) intervention 3: 10ml Ropivacaine 0.75% for distal sciatic nerve block (not in outpatients) intervention 4: 10ml Prilocaine 1% for saphenous nerve block intervention 5: In group US the sciatic nerve localization and needle guidance is realized using ultrasound. intervention 6: 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.

Protocol document: