Kewlani A, Bhatia N, Makkar JK, et al. - Via performing this dose-finding study, researchers sought to determine the median effective dose of 0.5% ropivacaine needed to produce a successful costoclavicular block for surgical anesthesia in 50% of the patients (ED50). In addition, they calculated the dose required for effective blockade in 95% of the patients (ED95). In this single-armed prospective study, they assessed 40 American Society of Anesthesiologists physical status I or II patients, aged 18 to 60 yr, with a BMI of 18 to 30 kg/m ², scheduled to undergo forearm and hand surgeries under ultrasound-guided costoclavicular block. The sample up-and-down sequential allocation study design of binary response variables was used to determine a volume of 0.5% ropivacaine administered in the costoclavicular space. A volume of 26 ml of 0.5% ropivacaine was administered to the first patient. Following a successful or unsuccessful block, decrease or increase in the volume of local anesthetic was done, respectively, by 2 ml in the next patient. Based on outcomes, they suggest a 19-ml dose of 0.5% ropivacaine may produce an effective ultrasound-guided costoclavicular block for providing adequate surgical anesthesia to 95% of the patients.