The Intrathecal Morphine for Percutaneous Endoscopic Lumbar Discectomy (IMPELD) Study: Rationale and Protocol for a Double-blinded Randomized Placebo-controlled Trial

Abstract Background Percutaneous endoscopic lumbar discectomy (PELD), a minimally invasive spinal technique for lumbar disc herniation (LDH), has gained popularity globally and yielded satisfying results. However, PELD is often performed on awaking patients to avoid nerve injury, thus the intraoperative analgesia of PELD is sometimes insufficient. The effect of intrathecal morphine (ITM) has been well proved in various surgical specialties, and this study aims to investigate the effectiveness and safety of ITM on PELD. Methods The intrathecal morphine for percutaneous endoscopic lumbar discectomy (IMPELD) trial is a double-blind, randomized, placebo-controlled trial. The 90 eligible LDH patients undergoing PELD will be randomly assigned to receive either ITM or placebo during spinal anesthesia, at a 1:1 ratio, with a one-month follow-up period. Average intraoperative pain intensity will be the primary outcome. Secondary outcome measures include intraoperative pain intensity assessed at each 30 min intraoperatively, postoperative pain intensity, perioperative analgesia requirements, functional evaluation, radiographic characteristics, overall satisfaction, other characteristics and adverse events. Discussion Currently, there is a lack of scientific evidence to provide a reliable method to reduce intraoperative pain of PELD. The IMPELD trial was designed to provide evidence regarding whether 100 ug of ITM is an effective and safe coanalgesic approach for PELD procedure. Trial registration The trial was registered with the Chinese Clinical Trial Registry (identifier ChiCTR2000039842). Registered on November 11 th , 2020.