The 90% minimum effective volume and concentration of ropivacaine for ultrasound-guided median nerve block in children aged 1–3 years: A biased-coin design up-and-down sequential allocation trial

Median nerve block can provide excellent analgesia during open surgery for trigger thumb in children. However, no data on the 90% minimum effective volume (MEV90) and concentration (MEC90) of ropivacaine for ultrasound-guided median nerve block in pediatric patients have been reported. A prospective two-phase study with an up-and-down sequential allocation trial using a biased coin design. Children aged 1–3 years are experiencing open surgery for trigger thumb. This study has 2 parts, one for MEV90 and subsequently studied MEC90 from the former part of the study. The MEV90 and MEC90 of ropivacaine for each subsequent patient were determined by the response of the previous patient, with the biased coin design up-and-down sequential allocation trial. The interval of -volume or concentration was -0.1 ml or 0.01%, respectively. The MEV90 and MEC90 of ropivacaine for ultrasound-guided median nerve block in pediatric patients, were then used to estimate the 99% minimum effective volume (MEV99) and concentration (MEC99). The patient's general condition, postoperative pain, and adverse events. A total of one hundred and eighteen children were enrolled for the study, and 56 and 62 patients were enrolled for the MEV90 and MEC90 studies, respectively. The MEV90 of 0.2% ropivacaine was 1.44 ml (95% CI 1.043 ml, 1.466 ml), and the MEC90 of 1.5 ml ropivacaine was 0.195% (95% CI 0.159%, 0.197%). There were no adverse events that occurred. For ultrasound-guided median nerve block in children aged 1–3 years old with trigger finger undergoing open surgery, the MEV90 of 0.2% ropivacaine is 1.44 ml (95% CI 1.043 ml, 1.466 ml), and the MEC90 of 1.5 ml of ropivacaine is 0.195% (95% CI 0.159%, 0.197%). •The 90% minimum effective volume (MEV90) and concentration (MEC90) of ropivacaine for ultrasound-guided median nerve block in pediatric patients have not been determined.•This study has 2 parts, one for MEV90 and subsequently studied MEC90 from the former part of the study, to explore the ideal combination of ropivacaine concentration and volume in children aged 1-3 years are experiencing open surgery for trigger thumb.•The MEV90 of 0.2% ropivacaine was 1.44 ml (95% CI 1.043 ml, 1.466 ml), and the MEC90 of 1.5 ml of ropivacaine was 0.195% (95% CI 0.159%, 0.197%).