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

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          After knee surgery, analgesia should be effective for mobilization and discharge.

          Aim of the Study

          The primary objective of this study was to achieve the lowest effective analgesic concentration (MEC50 and MEC90) of ropivacaine for saphenous nerve block in arthroscopic meniscectomy. The secondary objective was to determine whether the block causes muscle weakness in the postoperative period.


          The study was randomized, comparative, and double-blind. Fifty-one patients between 18 and 65 years old of both sexes, ASA I or II, who underwent knee arthroscopic meniscectomy at São Domingos Hospital were included. Patients underwent saphenous nerve block with 10 mL of ropivacaine administered by using the up-and-down method. The ropivacaine concentration was determined based on the previous patient’s response (a biased-coin up-down design sequential method). If a patient had a negative response, the concentration of ropivacaine was increased by 0.05% in the next patient; if the response was positive, the next patient was randomized to be administered the same concentration of ropivacaine or a 0.05% lower concentration. Successful block was defined as pain <4 during 6 h. Patients underwent general anesthesia with 30 µg/kg alfentanil and propofol and maintenance with propofol, and, if necessary, remifentanil was administered. Postoperative analgesia was complemented with dipyrone, and if necessary, tramadol (100 mg) could be used. The following parameters were assessed: the success of the block; pain intensity after 2, 4, and 6 h; the consumption of remifentanil; time to the first analgesic supplementation; percent of patients who needed analgesics during 6h; and muscle strength.


          The MEC50 of ropivacaine was 0.36%, and the MEC90 was 0.477%. The block was successful in 45 patients.


          Saphenous block with 10 mL of 0.36% ropivacaine provides adequate analgesia for outpatient meniscectomy.

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          Most cited references 24

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          Advances in and limitations of up-and-down methodology: a précis of clinical use, study design, and dose estimation in anesthesia research.

          Sequential design methods for binary response variables exist for determination of the concentration or dose associated with the 50% point along the dose-response curve; the up-and-down method of Dixon and Mood is now commonly used in anesthesia research. There have been important developments in statistical methods that (1) allow the design of experiments for the measurement of the response at any point (quantile) along the dose-response curve, (2) demonstrate the risk of certain statistical methods commonly used in literature reports, (3) allow the estimation of the concentration or dose-the target dose-associated with the chosen quantile without the assumption of the symmetry of the tolerance distribution, and (4) set bounds on the probability of response at this target dose. This article details these developments, briefly surveys current use of the up-and-down method in anesthesia research, reanalyzes published reports using the up-and-down method for the study of the epidural relief of pain during labor, and discusses appropriate inferences from up-and-down method studies.
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            Complications of peripheral nerve blocks.

            Complications of peripheral nerve blocks are fortunately rare, but can be devastating for both the patient and the anaesthesiologist. This review will concentrate on current knowledge about peripheral nerve injury secondary to nerve blocks, complications from continuous peripheral nerve catheter techniques, and local anaesthetic systemic toxicity.
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              Staircase bioassay: The up-and-down method

               W.J. Dixon (1991)

                Author and article information

                J Pain Res
                J Pain Res
                Journal of Pain Research
                13 January 2021
                : 14
                : 53-59
                [1 ]Universidade Federal de São Paulo , Department of Anesthesia, São Paulo, Brazil
                [2 ]Universidade Federal do Maranhão , Department of Medicine, São Luiz, Maranhão, Brazil
                Author notes
                Correspondence: Rioko Kimiko Sakata Email rsakata@unifesp.br
                © 2021 Rey Moura et al.

                This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms ( https://www.dovepress.com/terms.php).

                Page count
                Figures: 2, Tables: 5, References: 24, Pages: 7
                Clinical Trial Report

                Anesthesiology & Pain management

                mec90, mec50, meniscectomy, up-and-down, block, saphenous nerve


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