UC San Diego

BACKGROUND: A novel device integrating both local anesthetic delivery and peripheral nerve stimulation (PNS) to treat postoperative pain is under development. The device uses a catheter-over-needle design that permits ultrasound-guided percutaneous insertion. An integrated electrode and pulse generator enable PNS for up to 28 days. Such an approach may represent a paradigm shift in postoperative pain management by enabling the delivery of (1) a single-injection peripheral nerve block, (2) a continuous peripheral nerve block, and (3) neuromodulation-all through a single system that can be placed in a timeframe comparable with that of a traditional single-injection nerve block. The current prospective pilot study was executed under a US Food and Drug Investigational Device Exemption to develop insertion and management protocols, as well as assess the feasibility and safety of using the device to treat postoperative pain. METHODS: Preoperatively, adults (n=20) undergoing moderate-to-severely painful ambulatory shoulder or foot/ankle surgery had a device (RELAY, Gate Science, Moultonborough, NH) inserted under ultrasound guidance adjacent to the brachial plexus or sciatic nerve, respectively. Accurate insertion was confirmed with a 10 mL bolus of lidocaine via the catheter followed by bupivacaine (10 mL). If a continuous infusion was indicated, a portable pump was used to infuse ropivacaine (6-8 mL/h, 500 mL reservoir). Electric current was delivered using the integrated pulse generator for 7 days, followed by removal at home. Participants were contacted for data collection on postoperative days 1-5, 7, 8, and 14. RESULTS: During the first seven postoperative days, the median (IQR) "average" daily pain intensity as measured with the numeric rating scale (NRS) was 2 [0, 3]. Following postoperative day 1, daily average and maximum/worst NRS was less than 2 and 5, respectively. Regarding the "worst" (maximum) pain level over the entire study period of Days 0-14, 7 (35%) experienced mild pain (NRS<4), 10 (50%) moderate pain (NRS 4-7), and 3 (15%) severe pain (NRS>7). Cumulative oxycodone consumption the first week was a median of 43 (18, 73) mg. CONCLUSIONS: This novel device successfully delivered a single-injection local anesthetic bolus, a continuous perineural infusion, and concurrent/subsequent electrical current. A randomized, sham-controlled clinical trial appears warranted. CLINICALTRIALSGOV : NCT06818708.