Comparison of ultrasound and nerve stimulation for interscalene catheter placement

Interscalene catheter placed using either ultrasound or nerve stimulation Ultrasound (US) Group The needle will be advanced superficially in a caudal and peripheral direction until tissue displacement is observed just lateral to the brachial plexus trunks in the body of the middle scalene muscle. Dextrose 5% 5-10 mL will be injected down the needle to observe for appropriate fluid spread adjacent to the brachial plexus trunks, and a non-stimulating catheter advanced 2 cm past the needle tip. If US imaging proves difficult, a brief appropriate muscle twitch will be sought with a nerve stimulator set to 0.8 mA to confirm brachial plexus position. Sustained muscle twitches at 0.2-0.5mA will not be sought. If satisfactory US images cannot be attained within 5 min, the probe will be discarded and interscalene catheter (ISC) placement conducted blind as per the NS group. Duration of procedure: 15 min