Median effective volume of ropivacaine 0.5% for ultrasound-guided adductor canal block

Abstract

ObjectiveThis study aimed to identify the median effective volume of ropivacaine 0.5% for ultrasound-guided adductor canal block (ACB).MethodsThirty-two patients received ultrasound-guided ACB for knee arthroscopic meniscectomy. The criterion for successful ACB was the loss of pinprick sensation in the saphenous area (medial knee, leg, and foot). The volume of ropivacaine 0.5% in each case was determined using the up-down method and used for calculating the median effective dose.ResultsThe mean age, weight, and height of patients were 28.6 ± 7.1 years, 68.2 ± 10.6 kg, and 172.5 ± 6.4 cm, respectively. Among patients who received 18- and 15-mL doses, ACB was successful in all four cases. Among patients who received a 12-mL dose, ACB was effective in eight and ineffective in two cases. Among patients who received a 10-mL dose, ACB was successful in six and unsuccessful in seven cases. In patients who received an 8-mL dose, ACB was ineffective in all five cases. The median effective volume of ropivacaine 0.5% was 10.4 mL (95% confidence interval, 9.1–11.4 mL). In all effective cases, the median quadriceps strength was grade 5.ConclusionsThe median effective volume of ropivacaine 0.5% is 10.4 mL for ultrasound-guided ACB.

Early Postoperative Pain Control and Inflammation for Total Knee Arthroplasty: A Retrospective Comparison of Continuous Adductor Canal Block versus Single-Shot Adductor Canal Block Combined with Patient-Controlled Intravenous Analgesia

“…As we all know, the concentration and dose of local anesthetics have a great influence on the effect and duration of nerve block and that increasing the concentration and dose of local anesthetics carries the risk of causing systemic toxicity. The concentration of ropivacaine used for adductor canal block has been reported to vary widely from 0.1% to 0.75% [ 20 , 28 , 29 ], and the dosage of ropivacaine also varies widely from 5 ml to 40 ml [ 10 , 15 , 30 , 31 ]. Wang et al had found that EV50 of 0.5% ropivacaine for ACB was 10.79 ml (95% CI 10.10–11.52 ml) [ 32 ].…”

Minimum Effective Analgesic Concentration of Ropivacaine in Saphenous Block Guided by Ultrasound for Knee Arthroscopic Meniscectomy: Randomized, Double-Blind Study

“…In this study, with 10 mL of ropivacaine, as recommended by Tao et al, 18 it was found that an MEC90% of 0.477% was the minimum effective concentration for saphenous block in arthroscopic meniscectomy.…”

Evaluation of ultrasound‐guided adductor canal block with two different concentration of bupivacaine in arthroscopic knee surgery: A feasibility study

“…We obtained concentrations of 0.25% and 0.16% by diluting the commercially available 0.5% concentration of bupivacaine with saline. Tao et al reported the median effective volume as 10.4 mL for ACB 27 . Although a relatively older publication reported ED95 volume as being 20 mL in ACB, lower use of lower volumes have been reported in many clinical studies 28 .…”

“…Tao et al reported the median effective volume as 10.4 mL for ACB. 27 Although a relatively older publication reported ED95 volume as being 20 mL in ACB, lower use of lower volumes have been reported in many clinical studies. 28 Also, a systematic review and meta-analysis on ambulatory arthroscopic knee surgery and anterior cruciate ligament reconstruction reported the median volume of local anaesthetic used as 15 mL (range: 7.5-30 mL).…”