Background A short acting spinal anesthetic facilitates smooth flow since quick recovery of motor function will facilitate unassisted ambulation. The aim of this study was to estimate the effective dose (ED90) of intrathecal 2-chloroprocaine 1% in outpatient knee arthroscopy.
Methods Two cohorts were included in two different hospitals. In cohort I, a randomized biased-coin up-and-down design with 40 patients was used to find the ED90. Four dose-levels of plain 2-chloroprocaine 1% were used: 25, 30, 35 and 40 mg. The identified primary outcome, the ED90, was validated in 50 patients in cohort II with an open label design. Secondary outcomes included time to complete recovery from motor and sensory block with spinal injection as time zero, peak sensory block level, urine retention and time until hospital discharge.
Results Forty patients were included in the final analysis in cohort I. The ED90 was estimated at 27.8 mg, successful spinal anesthesia was obtained in 38 patients (95%). Fifty patients were included in the final analysis in cohort II, 49 patients had successful anesthesia with a fixed round dose of 28 mg. In this Cohort, peak sensory block was T10/T11 (range: (L4–T4)). The median time to full recovery of the motor block was 60 min (45–60) and 90 min (75–105) for the sensory block. The mean time to hospital discharge was 2.9 hours (0.7).
Conclusion The ED90 of 2-chloroprocaine 1% in knee arthroscopy was estimated to be 27.8 mg. In an external population, the ED90 resulted in successful anesthesia in 98% of the patients (95% CI 89% to 100%).
Trial registration number Netherlands Trial Registry (NL6769).
- ambulatory care
- lower extremity
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
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Contributors EJW participated in the design of the study, coordinated the study, performed the database validation, wrote the manuscript and was the guarantor. JSHAK coordinated the patient recruitment, assessments and follow-up, performed the data entry and participated in writing the manuscript; RvdV participated in the design of the study, enrolled patients, administered anesthesia and participated in writing the manuscript; PMvdV participated in the design of the study, performed statistical analyses and participated in writing the manuscript; JvdA performed surgical procedures and participated in writing the manuscript; YZ, CS, FW and LK performed assessments and participated in writing the manuscript; EF, ELS and CB participated in writing the manuscript and approved the final version of the manuscript; MAdL participated in the design of the study, writing the manuscript and approved the final version of the manuscript.
Funding Support was provided solely from institutional and/or departmental sources.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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