Journal article
Determination of ED50 and ED95 of 0.5% Ropivacaine in Adductor Canal Block to Produce Quadriceps Weakness A Dose-Finding Study
Regional anesthesia and pain medicine, Vol.42(6), pp.731-736
11/01/2017
DOI: 10.1097/AAP.0000000000000638
PMID: 28991061
Abstract
Background and Objectives: Adductor canal block (ACB) is popular for knee analgesia because of its favorable effect on quadriceps strength. The aim of this study was to find the minimum volume of local anesthetic, which can be injected into the ACB that would result in quadriceps weakness.
Methods: This nonrandomized study used an up-and-down sequential allocation design. Twenty-six patients scheduled to undergo arthroscopic knee surgery received an ultrasound-guided ACB preoperatively. The initial volume of ropivacaine 0.5% injected was 30 mL, which was subsequently increased or decreased by 2 mL, depending on whether the previous subject had a 30% reduction in quadriceps function. The minimum effective volume in 50% of patients was determined using Dixon-Massey up-and-down method. The effective volume in 95% of patients was then calculated using probit transformation.
Results: The ED50 (minimum effective anesthetic volume in 50% of the subjects) needed for a 30% decrease in quadriceps power was 46.5 mL (95% confidence interval, 45.01-50.43 mL), and estimated ED95 (minimum effective anesthetic volume in 95% of the subjects) was 50.32 mL (95% confidence interval, 48.66-67.26 mL). The local anesthetic volume injected correlated with degree of quadriceps weakness at 20 minutes postblock (P < 0.001) and in the postanesthesia recovery unit (P = 0.032).
Conclusions: Significant quadriceps weakness is unlikely when clinically representative volumes of 0.5% ropivacaine is used for ACB performed using sonographic landmarks.
Details
- Title: Subtitle
- Determination of ED50 and ED95 of 0.5% Ropivacaine in Adductor Canal Block to Produce Quadriceps Weakness A Dose-Finding Study
- Creators
- David F. Johnston - Western UniversityRakesh V. Sondekoppam - University of AlbertaRobert Giffin - London Health Sciences CentreRobert Litchfield - Western Univ, London Hlth Sci Ctr, Dept Orthoped Surg, London, ON, CanadaSugantha Ganapathy - Western Univ, London Hlth Sci Ctr, Dept Anesthesia & Perioperat Med, London, ON, Canada
- Resource Type
- Journal article
- Publication Details
- Regional anesthesia and pain medicine, Vol.42(6), pp.731-736
- Publisher
- Bmj Publishing Group
- DOI
- 10.1097/AAP.0000000000000638
- PMID
- 28991061
- ISSN
- 1098-7339
- eISSN
- 1532-8651
- Number of pages
- 6
- Language
- English
- Date published
- 11/01/2017
- Academic Unit
- Anesthesia
- Record Identifier
- 9984296137302771
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