Effect of Proximal End versus Middle Continuous Adductor Canal Block after Total Knee Arthroplasty

Study Objective: In this study, we localized the proximal end of the abbductor canal (AC) at which the medial borders of the sartorius and adductor longus muscles align (visualized with ultrasound guidance) to evaluate the analgesic effect of proximal end versus middle continuous adductor canal blocks (ACBs).
Design: Prospective, randomized, double-blind, controlled study.
Setting: The study was performed in the procedure room, operating room, and the inpatient ward at the Peking Union Medical College Hospital (Beijing, China).
Patients: Patients between the ages of 18 and 70 years with an American Society of Anesthesiologists score of I-III who were scheduled for a unilateral total knee anthroplasty (TKA) were included. Sixty patients completed the study, including 30 in each treatment group.
Interventions: Patients undergoing a unilateral TKA were randomized to receive continuous ACB (loading dose of 10 ml of 0.2% ropivacaine, followed by 6 ml/h of 0.2% ropivacaine until 48 h after the surgery) at the proximal end or middle of the canal. All patients received patient-controlled intravenous analgesia with sulfentanil after the surgery.
Measurements: The primary outcome measure was the cumulative sulfentanil consumption within 24 h after surgery, which was analyzed using Mann-Whitney U tests. P-values <0.05 (two-sided) were considered statistically significant.
Main Results: The 24 h sulfentanil consumption was 0.22 µg/kg (interquartile range: 0.15–0.40 µg/kg) in the proximal end group and 0.39 µg/kg (interquartile range: 0.23–0.52 µg/kg) in the middle group (P = 0.026).
Conclusions: For patients undergoing TKA, the opioid-sparing effect of continuous ACB is improved with a catheter inserted at the level of the proximal end of the canal, which was identified as the intersection of the medial borders of satorious and adductor longus muscles in the ultrasound image, compared with at the middle of the canal

研究目的：本研究以超声引导下缝匠肌与长收肌内侧缘对齐处作为收肌管（adductor canal, AC）近端的定位标准，比较收肌管连续阻滞（adductor canal blocks, ACBs）分别实施于收肌管近端与中段时的镇痛效果。
研究设计：前瞻性、随机、双盲对照研究。
研究地点：本研究在中国北京协和医院的操作室、手术室及住院病房开展。
研究对象：纳入年龄18~70岁、美国麻醉医师协会（American Society of Anesthesiologists, ASA）分级I~III级、拟行单侧全膝关节置换术（total knee arthroplasty, TKA）的患者。最终共60例患者完成本研究，两组各30例。
干预措施：拟行单侧全膝关节置换术的患者被随机分配至收肌管近端组或中段组，接受连续收肌管阻滞：先给予10mL 0.2%罗哌卡因作为负荷剂量，随后以6mL/h的速率持续输注0.2%罗哌卡因，直至术后48小时。所有患者术后均接受舒芬太尼患者自控静脉镇痛。
观察指标：主要结局指标为术后24小时内舒芬太尼累计消耗量，采用Mann-Whitney U检验进行统计分析，双侧P值<0.05视为具有统计学显著性。
主要结果：近端组术后24小时舒芬太尼消耗量为0.22 μg/kg（四分位间距：0.15~0.40 μg/kg），中段组为0.39 μg/kg（四分位间距：0.23~0.52 μg/kg），组间差异具有统计学意义（P=0.026）。
结论：对于接受全膝关节置换术的患者，相较于在收肌管中段置管，于超声图像中定位的收肌管近端（即缝匠肌与长收肌内侧缘的交点处）实施连续收肌管阻滞，其阿片类药物节俭效应更为显著。