Performing regional anesthesia with a minimum effective volume (MEV) of local anesthetic may reduce the risk of systemic local anesthesia toxicity. The lateral sagittal infraclavicular block (LSIB) is a well-established anesthesia method for surgery distal to the shoulder. For LSIB using ropivacaine 7.5 mg/ml the MEV was previously not known and we estimated MEV95 to be 31 ml (95% CI, 18 – 45 ...