ED90 of spinal 2-chloroprocaine 1% in ambulatory knee arthroscopy up to 45 min: a randomized biased-coin- up-and-down sequential allocation trial.

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).

Chloroprocaine versus prilocaine for spinal anesthesia in ambulatory knee arthroscopy: a double-blind randomized trial.

BACKGROUND: In ambulatory lower limb surgery, spinal anesthesia with rapid onset and a short duration of block is preferable. We hypothesized that the use of 2-chloroprocaine would be associated with a faster motor block recovery compared with prilocaine in knee arthroscopy. A difference of 15 min was considered clinically relevant. METHODS: 150 patients were randomly allocated to receive intrathecally either 40 mg of 2-chloroprocaine or 40 mg of prilocaine. The primary outcome was the time to complete recovery from motor blockade. Secondary outcomes included time to full regression of sensory block, peak sensory block level, urine retention needing catheterization, time until hospital discharge, incidence of transient neurologic symptoms and patient satisfaction. RESULTS: Time to complete recovery from motor blockade was 15 min shorter for 2-chloroprocaine (median: 60 min; IQR: 60-82.5) than for prilocaine (median: 75 min; IQR: 60-90; p=0.004). 2-Chloroprocaine also resulted in faster full regression of sensory block (median: 120 min; IQR: 90-135 compared with median: 165 min; IQR: 135-190, p<0.001) and faster time to hospital discharge (mean difference: 57 min; 95% CI 38 to 77, p<0.001). Peak sensory block was higher in the 2-chloroprocaine group (median: T9; IQR: T6-T12 compared with median: T10; IQR: T8-T12, p<0.008). Patient satisfaction and urine retention needing catheterization were equal in both groups. CONCLUSIONS: In knee arthroscopy, spinal anesthesia with 2-chloroprocaine results in a faster recovery of motor and sensory block, leading to quicker hospital discharge compared with prilocaine. TRIAL REGISTRATION NUMBER: NTR6796.