Single and double injection paravertebral block comparison in reduction mammaplasty cases: a randomized controlled study

Background: This study compares the analgesic effects and dermatomal blockade distributions of single and double injection bilateral thoracic paravertebral block (TPVB) techniques in patients undergoing reduction mammaplasty. Methods: After obtaining ethics committee approval, 60 patients scheduled for bilateral reduction mammaplasty were included in the study. Preoperatively, the patients received one of single (Group S: T3–T4) or double (Group D: T2–T3 & T4–T5) injection bilateral TPVBs using bupivacaine 0.375% 20 ml per side. All patients were operated under general anesthesia. The T3–T6 dermatomal blockade distributions on the midclavicular line were followed by pin-prick test for 30 min preoperatively and 48 h postoperatively. All patients received paracetamol 1 g when numeric rating scale (NRS) pain score was ≥ 4, and also tramadol 1 mg/kg when NRS was ≥ 4 again after 1 h. The primary endpoint was NRS pain scores at postoperative 12th h. The secondary endpoints were dermatomal blockade distributions and NRS scores through the postoperative first 48 h, time until first pain and the analgesic consumption on days 1 and 2. Results: Fifty-two patients completed the study. The NRS pain scores at 12th h were similar (right side: P = 0.100, left side: P = 0.096). The remaining NRS scores and other parameters were also comparable within the groups (P ≥ 0.05). Only single injection TPVB application time was shorter (P < 0.001). Conclusions: The single injection TPVB technique provided sufficient dermatomal distribution and analgesic efficacy with the advantages of being faster and less invasive.研究背景：本研究对比单次注射与双次注射双侧胸椎旁阻滞（TPVB）技术在接受双侧乳房缩小成形术患者中的镇痛效应与皮节阻滞分布情况。 研究方法：本研究经伦理委员会批准后，纳入60名拟行双侧乳房缩小成形术的患者。术前将患者分为两组，分别接受单侧剂量为0.375%布比卡因20ml的单次注射双侧胸椎旁阻滞（S组：T3~T4），或双次注射双侧胸椎旁阻滞（D组：T2~T3及T4~T5）。所有患者均采用全身麻醉。分别于术前及术后48小时内，采用针刺试验对锁骨中线处的T3~T6皮节阻滞分布进行评估。当数字疼痛评分量表（NRS）评分≥4分时，所有患者予以对乙酰氨基酚1g；若1小时后NRS评分仍≥4分，则追加曲马多1mg/kg。本研究的主要终点为术后12小时的NRS疼痛评分；次要终点包括术后48小时内的皮节阻滞分布与NRS评分、首次疼痛出现时间，以及术后第1、2日的镇痛药物消耗量。 研究结果：最终共有52例患者完成本研究。两组患者术后12小时的NRS疼痛评分无显著差异（右侧：P=0.100，左侧：P=0.096）。其余NRS评分及其他参数组间亦无统计学差异（P≥0.05），仅单次注射胸椎旁阻滞的操作时长更短（P<0.001）。 研究结论：单次注射胸椎旁阻滞技术可实现充足的皮节阻滞范围与镇痛效果，且具备操作更快捷、创伤更小的优势。