A New Stimulating Stylet for Immediate Control of Catheter Tip Position in Continuous Peripheral Nerve Blocks

Abstract

To the Editor: Since the first description by Ansbro in 1946 [1], different catheter systems have been developed to facilitate catheter placement [2]. However, there is no efficient means, except radiographic studies, for immediate control of correct catheter tip position. We designed new equipment (Figure 1) consisting of a 20-gauge, single-hole, polyamide catheter (400 mm length) with an indwelling removable conducting stylet (405 mm length). The conducting metal wire is insulated with Teflon coating, except for the last 0.3 mm, and has a rounded, atraumatic tip. The reliability of this device was evaluated by using the first 10 prototypes in continuous supraclavicular brachial plexus blocks [3]. In 8 of the 10 patients studied, motor responses to stimulation through the catheter were identical to those elicited by the needle used for the localizing puncture (Stimulong Catheter Set; Pajunk, Geisingen, Germany). In two patients, threading of the catheter was only possible after multiple punctures and dilation with >10 mL of saline; satisfying motor response to neurostimulation (<1 mA) could not be obtained with the stimulating stylet. Radiographic studies confirmed correct catheter position in all patients. In this preliminary study, we showed that a stimulating stylet can allow easy and immediate confirmation of catheter tip position in continuous brachial plexus block and makes radiographic control unnecessary in most patients. A comparative study to evaluate whether the new device improves the success rate without introducing new complications is in process.Figure 1: Left, 20-gauge polyamide catheter, length 40 mm. A, Plug to connect the stimulating stylet to a nerve stimulator. Right, Enlargement of the catheter tip. B, Tip of the 20-gauge, single-hole polyamide catheter with radiopaque line. C, Teflon-coated removable stimulating style. D, Bare atraumatic tip for stimulation.Ottmar Kick, MD Emmanuel Blanche, MD Charles Pham-Dang, MD Michel Pinaud, PhD * Service d'Anesthesie-Reanimation Chirurgicale; Hotel Dieu; Nantes, France Jean Pierre Estebe, MD [dagger] Department d'Anesthesie-Reanimation; Pontchaillou, Rennes, France