Impact of Self-Coiling Catheters for Continuous Popliteal Sciatic Block on Postoperative Pain Level and Dislocation Rate: A Randomized Controlled Trial

Background : Catheter dislocation within the tissue is a challenge in continuous regional anesthesia. A novel self-coiling catheter design has been available providing lower dislocation rate in a cadaver model. So far it hasn´t been demonstrated whether the self-coiling catheter offers any remarkable advantages for continuous peripheral regional anesthesia in vivo. Methods: After ethics committee approval 140 patients undergoing elective distal lower limb surgery were enrolled in this prospective randomized controlled trial. Preoperatively, patients were randomly assigned and received either the conventional (n=70) or self-coiling catheter (n=70) for ultrasound-guided popliteal sciatic nerve block in short axis view and in-plane approach from lateral. The primary endpoint was pain intensity after surgery and on the following days. Secondary outcomes investigated were dislocation rate in situ, externally visible catheter movement, opioid consumption as well as leakage at the puncture site. Results: All catheters were successfully inserted. The study population of self-coiling catheters had significantly lower mean numeric rating scale values than the reference cohort on the first (p=0.01) and second postoperative days (p<0.01). Sonographic evaluation has shown, 42 standard catheters (60 %) and 10 self-coiling catheters (14.3 %) were dislocated in situ within the first three postoperative days. The externally visible movement of the catheters at insertion site did not differ significantly and was on average less than 0.5 cm on the third day. The amount of opioids administered was significantly lower in the self-coiling catheter group on the day of surgery and on the second and third postoperative days (p=0.04, p=0.03 and p=0.04, respectively). Conclusion: The self-coiling catheter offers a superior postoperative pain control and a lower dislocation rate within the tissue for popliteal sciatic nerve blockade compared to a conventional catheter. Further trials in large patient cohorts are warranted to investigate potential beneficial effects of self-coiling catheters for other localisations and other application techniques. Trial registration : The trial was registered at German Clinical Trials Register (DRKS) on 08/04/2020 (DRKS00020938, retrospectively registered).