Non-efficacy of ultrasound-guided erector spinae plane block in postoperative analgesia of non-instrumented spine surgery: a randomized, double-blind, controlled trial.

Introduction: Postoperative pain management is a challenge after lumbar spine surgery. Erector spinae plane (ESP) block is one solution and seems to limit opioid consumption after lumbar fusion. This RCT explored the effectiveness of ESP block versus placebo in non-instrumented spine surgery within an ERAS program. Research question: The hypothesis suggested the superiority of ESP block across all endpoints, emphasizing its potential as a safe and effective element. Material and methods: In this prospective, single-center, randomized, double-blinded controlled trial using a 1:1 allocation with an intent-to-treat, patients undergoing non-fusion lumbar surgery for one or two levels were included from January to November 2022. Ultrasound-guided ESP block was performed by an anesthesiologist injecting levobupivacaine or saline solution (placebo). The primary outcome was total morphine consumption at 72 h. Results: We included 100 individuals (50 in each arm). Total morphine consumption at 72 h did not differ between the ESP block and placebo groups, nor did cumulative pain score, intraoperative sufentanil administration, 1-month ODI and pain scores. In the daily analysis, morphine consumption was greater in the placebo group at day 0, and in the ESP block group from day 1 to day 3, without significance. The pain scores throughout the first 72 postoperative hours were <3/10 in both groups. Discussion and conclusion: The groups did not differ in morphine consumption at 72 h postoperatively. Increased morphine dose after the first 24 h in the ESP block group could suggest a rebound effect. In patients undergoing non-instrumented spine surgery, the ESP block does not confer additional analgesic benefits.