A Novel Percutaneous Device Enabling both Local Anesthetic Delivery and Electrical Stimulation (Neuromodulation) of Peripheral Nerves for Pain Following Orthopaedic Surgery: An Initial Feasibility Technical Report

Introduction Pain following orthopaedic surgical procedures remains undertreated due to inadequate analgesic options. One possible solution is a novel device currently under investigation. The RELAY system (Gate Science, Moultonborough, NH) is comprised of a basic catheter-over-needle device to allow ultrasound-guided percutaneous insertion, leaving a perineural catheter after simple withdrawal of the internal needle. A single-injection bolus of local anesthetic may be quickly administered. Following surgery, the catheter may be attached to a portable infusion pump to provide an ambulatory continuous peripheral nerve block. Unlike previously described perineural catheters, the RELAY has an embedded wire and integrated pulse generator that permit stimulation of the targeted peripheral nerve(s) for up to 28 days. We here provide the first description of this novel device when used to provide postoperative analgesia. Case Report A 67-year-old woman undergoing unilateral (right), primary reverse total shoulder arthroplasty provided written, informed consent and had a RELAY inserted under ultrasound guidance with a single pass. A single-injection nerve block was induced with lidocaine 2% (10 mL) and bupivacaine 0.5% (10 mL), both with epinephrine. A ropivacaine 0.2% infusion was initiated with a portable infusion pump via the catheter. Following surgery, the patient reported no surgical pain and her pulse stimulator initiated with a current of 2.2 mA. She was discharged home with the device in situ. Postoperative day (POD) 1 her maximum and average pain measured with a numeric rating scale (NRS) were 3 and 1. During her ropivacaine infusion her worst and average pain scores were 1 and 0, respectively. Following POD 4 (ropivacaine reservoir exhaustion on POD 3) she experienced no pain with active stimulation. The catheter/lead was removed at home by her caretaker without difficulty on POD 7. Conclusions This new device represents a feasible intervention for postoperative pain management in ambulatory settings and further investigation is warranted.