Department of Orthopaedics surgery, West China Hospital, 34753Sichuan University, Chengdu, China.
Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China.
J Orthop Surg (Hong Kong). 2022 May-Aug;30(2):10225536221122339. doi: 10.1177/10225536221122339.
This study aimed to investigate the minimum effective concentration (MEC defined as effective in 90% of patients) of ropivacaine during the combined procedure of adductor canal block (ACB) and infiltration between the popliteal artery and capsule of the posterior knee (IPACK) block for patients undergoing total knee arthroplasty.
This double-blind, randomized dose-finding trial was based on a biased coin up-and-down sequential design, where the concentration of ropivacaine administered to a given patient depended on the previous patient's response. Before surgery, the first patient received 20 mL of 0.2% ropivacaine for ACB and again for IPACK. If the block failed, the next subject received a 0.025% higher ropivacaine concentration; otherwise, the next subject received either a 0.025% smaller dose (probability of 0.11) or the same dose (probability of 0.89). The primary outcome was whether the block was successful. Block success was defined as the patient did not suffer significant pain and did not receive rescue analgesia within 6 h after surgery. MEC was estimated by isotonic regression, and the 95% confidence interval (CI) was calculated by bootstrapping. Secondary outcomes were numerical rating scale (NRS) pain scores at postoperative 24 h and 48 h, postoperative morphine consumption, and time to hospital discharge. Secondary outcomes were compared between patients whose blocks succeeded with those which failed.
Based on analysis of 52 patients, the MEC was 0.247% (95% CI 0.227-0.271%), MEC was 0.260% (95% CI 0.244-0.282%) and MEC was 0.272% (95% CI 0.260-0.291%). In contrast, four of nine trials in a recent systematic review reported ropivacaine concentrations below 0.247%. Patients whose blocks succeeded ( = 45) had significantly lower NRS pain scores, lower morphine consumption, and shorter hospitalization than patients whose blocks failed ( = 7).
Our small trial suggests that 0.247% ropivacaine in 20 mL respectively can provide successful ACB + IPACK block in 90% of patients. However, given that many published trials have used lower concentrations, our findings should be verified in larger studies.
本研究旨在探讨股神经阻滞（ACB）联合胭窝动脉与后膝囊间隙浸润阻滞（IPACK）时罗哌卡因的最小有效浓度（MEC，定义为 90%患者有效），用于接受全膝关节置换术的患者。
这是一项基于偏倚硬币上下序贯设计的双盲、随机剂量发现试验，给予某一患者的罗哌卡因浓度取决于前一位患者的反应。手术前，第一例患者接受 20ml0.2%罗哌卡因用于 ACB 及再次用于 IPACK。如果阻滞失败，下一例患者接受 0.025%更高浓度的罗哌卡因；否则，下一例患者接受 0.025%更小剂量（概率为 0.11）或相同剂量（概率为 0.89）。主要结局是阻滞是否成功。阻滞成功定义为患者术后 6 小时内无明显疼痛且无需接受解救性镇痛。通过等渗回归估计 MEC，通过自举法计算 95%置信区间（CI）。次要结局为术后 24 小时和 48 小时的数字评分量表（NRS）疼痛评分、术后吗啡用量和出院时间。将阻滞成功的患者与阻滞失败的患者进行比较。
基于 52 例患者的分析，MEC 为 0.247%（95%CI0.227-0.271%），MEC 为 0.260%（95%CI0.244-0.282%）和 MEC 为 0.272%（95%CI0.260-0.291%）。相比之下，最近一项系统评价的九项试验中有四项报告罗哌卡因浓度低于 0.247%。阻滞成功的 45 例患者的 NRS 疼痛评分、吗啡用量和住院时间均显著低于阻滞失败的 7 例患者。
我们的小样本试验表明，20ml 中分别含有 0.247%的罗哌卡因可以为 90%的患者提供成功的 ACB+IPACK 阻滞。然而，鉴于许多已发表的试验使用了更低的浓度，我们的发现需要在更大的研究中验证。
