RESUMO
OBJECTIVE: This trial aimed to identify the Minimum Effective Concentration (MEC90, defined as the concentration which can provide successful block in 90% of patients) of 30 mL ropivacaine for single-shot ultrasound-guided transmuscular Quadratus Lumborum Block (QLB) in patients undergoing Total Hip Arthroplasty (THA). METHODS: A double-blind, randomized dose-finding study using the biased coin design up-and-down sequential method, where the concentration of local anesthetic administered to each patient depended on the response from the previous one. Block success was defined as a Numeric Rating Scale (NRS) score during motion ≤ 3 at 6 hours after arrival in the ward. If the block was successful, the next subject received either a 0.025% smaller dose (probability of 0.11) or the same dose (probability of 0.89); otherwise, the next subject received a 0.025% higher ropivacaine concentration. MEC90, MEC95 and MEC99 were estimated by isotonic regression, and the corresponding 95% Confidence Intervals (95% CIs) were calculated by the bootstrapping method. RESULTS: Based on the analysis of 52 patients, MEC90, MEC95, and MEC99 of ropivacaine for QLB were estimated to be 0.352% (95% CI 0.334-0.372%), 0.363% (95% CI 0.351-0.383%), and 0.373% (95% CI 0.363-0.386%). The concentration of ropivacaine at 0.352% in a volume of 30 ml can provide a successful block in 90% of patients. CONCLUSIONS: For ultrasound-guided transmuscular QLB in patients undergoing THA, 0.352% ropivacaine in a volume of 30 ml can provide a successful block in 90% of patients. Further dose-finding studies and large sample size are required to verify the concentration.
Assuntos
Artroplastia de Quadril , Humanos , Ropivacaina , Dor Pós-Operatória/prevenção & controle , Anestésicos Locais , Ultrassonografia de Intervenção/métodosRESUMO
Abstract Objective: This trial aimed to identify the Minimum Effective Concentration (MEC90, defined as the concentration which can provide successful block in 90% of patients) of 30 mL ropivacaine for single-shot ultrasound-guided transmuscular Quadratus Lumborum Block (QLB) in patients undergoing Total Hip Arthroplasty (THA). Methods: A double-blind, randomized dose-finding study using the biased coin design up-and-down sequential method, where the concentration of local anesthetic administered to each patient depended on the response from the previous one. Block success was defined as a Numeric Rating Scale (NRS) score during motion ≤ 3 at 6 hours after arrival in the ward. If the block was successful, the next subject received either a 0.025% smaller dose (probability of 0.11) or the same dose (probability of 0.89); otherwise, the next subject received a 0.025% higher ropivacaine concentration. MEC90, MEC95 and MEC99 were estimated by isotonic regression, and the corresponding 95% Confidence Intervals (95% CIs) were calculated by the bootstrapping method. Results: Based on the analysis of 52 patients, MEC90, MEC95, and MEC99 of ropivacaine for QLB were estimated to be 0.352% (95% CI 0.334-0.372%), 0.363% (95% CI 0.351-0.383%), and 0.373% (95% CI 0.363-0.386%). The concentration of ropivacaine at 0.352% in a volume of 30 ml can provide a successful block in 90% of patients. Conclusions: For ultrasound-guided transmuscular QLB in patients undergoing THA, 0.352% ropivacaine in a volume of 30 ml can provide a successful block in 90% of patients. Further dose-finding studies and large sample size are required to verify the concentration.
RESUMO
BACKGROUND: We aimed to determine the minimum effective volume (MEV) of 0.5% bupivacaine for infraclavicular brachial plexus block. METHODS: We assigned patients to volume groups consisting of five consecutive patients. Local anesthetic was sequentially reduced from a starting dose of 30 mL by 2 mL to form the volume groups. Five patients were included in each volume group, and at least 3 of 5 injections had to be successful to consider the volume of the anesthetic as sufficient. The study ended when the anesthetic volume of a group was determined to be unsuccessful (two or fewer successful blocks). Block was successful if the patient reported a sensorial block score of 7 or more on an 8-point scale and sensorial and motor block's total score of 14 on a 16-point scale. RESULTS: The MEV of 0.5% bupivacaine for infraclavicular brachial plexus block was 14 mL. A successful block was achieved in all patients (n = 45) in 9 volume groups, which received 30 mL down to 14 mL. Three blocks were unsuccessful in the 12-mL group. Time to onset of block and time to first postoperative anesthetic administration was 15 (10-15) min and more than 24 h in the 30-mL bupivacaine group, but 40 (30-45) min and 14 (10-24) h were determined for the 14-mL group, respectively. CONCLUSIONS: The MEV of 0.5% bupivacaine for ultrasound-guided infraclavicular brachial plexus block was 14 mL. However, this low-dose block has a long onset time of 40 (30-45) min on average.