US-guided Sciatic Nerve Block Clinical Trial
Official title:
Ultrasound-guided Popliteal Sciatic Nerve Block: an Evaluation of the Intraneural
This prospective, double-blinded study evaluates intraneural ropivacaine 1% Minimal Effective
Volume (MEV90) for ultrasound-guided (US) popliteal sciatic nerve block, with Up-and-down
methodology.
To evaluate any neurological complications, an electrophysiological assessment will also be
performed preoperatively and at 5 weeks after surgery.
At least 45 patients undergoing hallux valgus repair will be enrolled. A baseline bilateral
sciatic nerve electrophysiological study will be performed preoperatively.
Patients will be placed in prone position and a high-frequency (8-12 MHz) linear array
transducer (Snerve, Sonosite, USA) will be used to identify the sciatic nerve in a transverse
cross-sectional view at the apex of the popliteal fossa. As the best view of the sciatic
nerve with its paraneural and neural sheath, just proximal to the point of bifurcation, will
be obtained, the nerve dimension (medial-lateral and cranio-caudal diameters) will be
determined and registered.
An 80 mm 22-gauge needle (Sonoplex, Pajunk, Germany) will be inserted using the US-guided
in-plane technique under the epineurium. The positioning will be evaluated injecting 1 ml of
sodium-chloride 0.9% solution and observing the nerve swelling, if correct the local
anaesthetic (LA) solution will be injected.
The first patient will receive 15 ml of ropivacaine 1% (150 mg). Following patients will
receive LA volume based on Up-and-down methodology.
Clinical follow-up will be performed at 12, 24, 48 hours, 1 and 5 weeks and 6 months after
surgery.
At 5 weeks electrophysiological study will also be performed in all patients and repeated at
6 months in case of positive findings.
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