A novel concept for continuous peripheral nerve blocks. Presentation of a new ultrasound-guided device.

Abstract

Existing techniques for placing and maintaining the position of peripheral nerve catheters are associated with variable success rates and frequent secondary failures. These factors may affect the clinical efficacy and usefulness of peripheral nerve catheters. We developed a new concept and prototype for ultrasound-guided in-plane positioning and readjustment of peripheral nerve catheters (patent pending). The integrated catheter-needle prototype comprises three parts: a curved needle, a catheter with clear echogenic markings attached to the needle tail and a detachable hub allowing injection of local anesthetic while advancing the needle in the tissue. The system works like a suture and is introduced through the skin, passes in close relation to the nerve and exits through the skin. This allows in-plane ultrasound guidance throughout the procedure both during initial positioning as well as during later in-plane readjustment of the catheter. We tested the system in the popliteal region of two fresh cadavers in a preliminary proof of concept study. Both initial placement and secondary readjustment were precise, judged by the catheter orifices placed close to the sciatic nerve in the popliteal fossa. Circumferential spread of 3-ml isotonic saline around the sciatic nerve was observed on ultrasound images in both conditions. Preliminary proof of concept of this novel method demonstrates that precise in-plane ultrasound-guided initial placement and secondary in-plane readjustment is possible in fresh cadavers. Future studies should address the clinical efficacy and usefulness of this novel concept.