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.