Comparison between ultrasound-guided intertransverse process and erector spinae plane blocks for breast cancer surgery

BACKGROUND: Clinical comparisons between intertransverse process block (ITPB) and erector spinae plane block (ESPB) are lacking. OBJECTIVE: This study aimed to compare their blocking profile and clinical efficacy in breast cancer surgery. DESIGN: Randomised, blinded, active-controlled superiority trial. SETTING: A tertiary hospital in China from 20 February to 31 July 2023. PATIENTS: Sixty-eight females undergoing unilateral breast cancer surgery. INTERVENTION: Patients were randomised to receive either ITPB performed at T2-6 (5 ml of 0.5% ropivacaine per level) or ESPB at T4 (25 ml of 0.5% ropivacaine). General anaesthesia and postoperative analgesia were standardised. MAIN OUTCOME MEASURES: The primary outcome was the number of blocked dermatomes at anterior T2-7, assessed 45 min after block completion, with a predefined superiority margin of 1.5 dermatomes. The important secondary outcome was the worst resting pain scores (11-point numerical rating scale) within 30 min in the recovery room, which was tested following a gatekeeping procedure. Other secondary outcomes included resting pain scores at various time points, use of rescue analgesics, opioid consumption, patient satisfaction, recovery quality score, and adverse effects within 24 h postoperatively. RESULTS: The ITPB group showed a median [q1, q3] of 5 [4, 6] blocked dermatomes at anterior T2-7, whereas the ESPB group had 1 [0, 4], with a median difference of 4 (95% confidence interval (CI), 3 to 4); the lower 95% CI limit exceeded the predefined superiority margin of 1.5 (superiority P < 0.001). Worst resting pain scores within 30 min in the recovery room in the ITPB group were 1 [0, 2] vs. 3 [1, 4] in the ESPB group, with a median difference of -1 (95% CI, -2 to 0; P = 0.004). Patients in the ITPB group required fewer rescue analgesics within 30 min in the recovery room than did those in the ESPB group. No other clinically relevant results were observed in the secondary outcomes. CONCLUSIONS: Although ITPB demonstrated more consistent anterior dermatomal spread and improved immediate postoperative analgesia compared to ESPB, no additional benefits were identified for breast cancer surgery. Future studies may investigate the potential of ITPB for surgical anaesthesia. TRIAL REGISTRATION: www.chictr.org.cn (ChiCTR2300068454).