Minimum local analgesic concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children--analysis using the Dixon method.

摘要

Deng et al. recently quantified the minimal local anaesthetic concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children [1]. Although in their methods, the authors stated that the concentration of ropivacaine received by a particular subject was determined according to Dixon's up and down method, the ED_50 presented in the results was calculated using probit and logit regression only. We respectfully suggest that for proper analysis of the data, the ED_50 with 95% CI should have been estimated from the up-down sequences using the method of Dixon and Massey. The sequences should then have been subjected to probit regression analysis as a backup or sensitivity test.