With further study, EI could prove to be a quantifiable warning signal to alert clinicians to intraneural needle placement, preventing local anesthetic injection and subsequent nerve injury.

We report our successful experience using ultrasound guidance and nerve stimulation during supraclavicular blockade. The curvilinear probe enables a large field of view, adequate resolution in larger patients, and excellent needle visibility that allows access to the plexus while avoiding the pleura and subclavian artery.