The Efficacy of Different Ropivacaine Concentrations (0.5%, 0.6% vs 0.75%) for Regional Nerve Block in Lower Extremity

Abstract

Category: Basic Sciences/Biologics Introduction/Purpose: There have only been a few studies on optimal concentrations, doses, and volume of injection material in the regional nerve block for lower extremity operations. The purpose of this study was to evaluate the efficacy of different concentrations of ropivacaine with respect to anesthetic time, intraoperative, postoperative pain, and patient’s satisfaction. Methods: A total of 339 patients underwent lower extremity surgery under ultrasound-guided nerve block (combined femoral and sciatic nerve block) at a single institution between March 2016 and February 2017 and were randomly assigned to three groups: Group A (0.5% 42 ml), B (0.6%, 30 ml), and C (0.75%, 30 ml). The interval between nerve block procedure and onset of the complete anesthetic effect (complete anesthetic time) was investigated. The degrees of intraoperative pain (during the first 10 minutes of the surgical procedure), and postoperative pain (6, 12 hours after operation) were evaluated using a visual analog scale (VAS) score. Patient’s satisfaction (0~10) was investigated 12 hours after the operation. To evaluate the efficacy in accordance with the concentration under the same dose and same volume, group A and B were compared with group C respectively. Results: There were 108, 118, and 113, in groups A, B, and C, respectively. The complete anesthetic times were 78.5, 76.4, and 58.6 minutes, respectively. The intraoperative VAS scores were 2.04, 0.62, and 0.24; and the postoperative VAS scores (6hours / 12hours) were 2.41 / 4.08, 0.26 / 1.24, and 0.38 / 1/53. The patient’s satisfactory scores were 8.53, 9.38, and 9.4 respectively. Compared with group C, group A showed significantly longer complete anesthetic time (p<0.05) and higher intra, postoperative VAS scores (all p<.05). Group B showed longer complete anesthetic time (p<0.05), but no significant difference of intra, postoperative VAS scores (all p>.05). Patient’s satisfactory scores in both group A and B were similar to group C(p>.05, p>.05). There were no adverse reactions in all groups. Conclusion: Ropivacaine 0.6% as well as 0.75% are safe and effective anesthetics under the same volume (30 ml) for regional nerve block of the lower extremity. However, taking into account of the longer complete anesthetic time, the operation start time must be adjusted.