Evaluation of the efficacy of dexmedetomidine as an adjuvant to ropivacaine in single-injection erector spinae plane block on chronic postsurgical pain after video-assisted thoracoscopic surgery: a randomized, double-blind controlled trial

Chronic postsurgical pain (CPSP) remains common after video-assisted thoracoscopic surgery (VATS). This study aimed to evaluate whether the addition of dexmedetomidine as an adjuvant to ropivacaine in erector spinae plane block (ESPB), compared with ropivacaine alone, reduces the incidence of CPSP in patients undergoing VATS. In this single-center, randomized, double-blind controlled trial, 140 patients scheduled for elective VATS were randomly assigned in a 1:1 ratio to ultrasound-guided ESPB with 20 mL of 0.375% ropivacaine alone (R group) or with 20 mL of 0.375% ropivacaine plus dexmedetomidine 1 µg/kg (RD group). The primary outcome was the incidence of CPSP at 3 months, defined as a numeric rating scale (NRS) score of 1 or more at the surgical site. Secondary outcomes included acute postoperative NRS scores, Richmond Agitation-Sedation Scale (RASS) scores, perioperative opioid consumption, recovery-related outcomes and, in patients who reported persistent pain at 3 months, the Douleur Neuropathique 4 (DN4) questionnaire and the Brief Pain Inventory-Short Form (BPI-SF). Of the 140 randomized patients, 121 (R group, n = 60 RD group, n = 61) were included in the primary analysis. At 3 months, CPSP had occurred in 11 of 60 patients (18.3%) in the R group and 17 of 61 patients (27.8%) in the RD group (risk difference 9.5% points, 95% CI -5.4 to 24.5, risk ratio 1.52, 95% CI 0.78 to 2.97, two-sided Fisher exact P = 0.28). Nausea and vomiting was the only adverse event recorded, in 4 of 60 patients (6.7%) in the R group and 8 of 61 patients (13.1%) in the RD group (Fisher exact P = 0.36). No serious adverse events occurred. Compared with the R group, the RD group had lower resting NRS scores at 72 h (median [interquartile range] 0 [0–1] versus 1 [1–1] P = 0.018) and a lower BPI-SF pain interference score at 3 months (2 [1–2] versus 2 [2–3] P = 0.003). No significant differences were observed in DN4 scores, BPI-SF pain severity scores, RASS scores, opioid consumption, duration of chest tube drainage, post-anaesthesia care unit (PACU) stay or postoperative length of hospital stay. In patients undergoing VATS, adding dexmedetomidine to single-injection ropivacaine ESPB did not reduce the 3-month incidence of CPSP. It was associated with lower resting NRS scores at 72 h and with reduced pain-related interference with daily functioning at 3 months. These secondary findings are exploratory. Chinese clinical trial registry, ChiCTR2400083431 (registered retrospectively on 24 April 2024).