The Impact of Local Anesthetic Dilution on Possible Blinding for Nerve Blocks

"The study uses ropivacaine for nerve blocks, starting at 0.1% concentration and capped at 0.5% for safety. Concentration adjustments are made based on each participant's response 60 minutes post-injection:~* Increase by 0.025% if pain reduction is \<50%~* Increase by 0.025% if reduction is 50-75% without sensory/motor block~* Decrease by 0.025% if reduction is 50-75% with sensory/motor block~* Decrease by 0.025% if reduction is \>75%. Pain is assessed using a Numerical Rating Scale. The study employs Dixon's up-and-down method for five cycles to determine the optimal concentration for effective pain relief without significant numbness or weakness."

0.9 % NaCl solution (saline) injection