Effects of erector spinae plane block on postoperative pain in patients undergoing implant-based breast reconstruction for breast cancer: a randomized controlled trial.

Implant-based breast reconstruction after mastectomy causes acute pain. To determine whether a single-shot T5 erector spinae plane block (ESPB) reduces postoperative pain. Single-center, RCT with allocation concealment; blinded assessors and statisticians. Tertiary cancer center in China. 100 adults scheduled for radical mastectomy with implant reconstruction were randomized (1:1); follow-up complete. Before induction, ESPB was given under ultrasound guidance at T5 with 30 mL of 0.375% ropivacaine plus dexmedetomidine 1 μg/kg; controls received no block. Standardized general anesthesia and postoperative PCA for both groups. Resting NRS at 6 h (MCID=1). Secondary outcomes were opioid consumption, quality of recovery, and PONV. ESPB did not significantly reduce resting pain at 6 h at the median (τ =0.50; adjusted difference -0.9; p = 0.08). At the upper tail, pain intensity was lower (τ = 0.75; -1.8; p <0.01). Repeated measures provided additional time-point information, improving estimation precision and test sensitivity. ESPB get lower pain scores at 6, 12, and 24 hours (all p <0.01). But, the 95% CI includes the MCID, the clinical benefit remains uncertain. Opioid use decreased at 24 h (-13.5 mg; p <0.01) and 48 h (-6.6 mg; p <0.01). Quality of recovery improved at 24 h (difference 5 points; p <0.01), but not later. No differences were observed in intraoperative hemodynamics or PONV. Single-shot T5 ESPB with perineural dexmedetomidine may reduce postoperative pain and opioid requirements and improve early recovery. Further large trials are warranted. Clinical relevance remains to be confirmed. ClinicalTrials.gov NCT06143020.