Comparison of the effect of two different doses of 0.75% glucose-free ropivacaine for spinal anesthesia for lower limb and lower abdominal surgery

We compared the clinical efficacy and safety of two doses of ropivacaine for spinal anesthesia in Chinese patients undergoing lower limb and lower abdominal surgery. In this randomized, open-label study, 40 patients were divided into two groups: group A received 3.5 mL (26.25 mg) of 0.75% glucose-free ropivacaine, and group B received 4.5 mL (33.75 mg). Sensory and motor blocks were assessed during and after surgery through to complete recovery. Seven standard measurements were taken: time to onset of sensory blocks; maximum sensory cephalad spread; time to maximum sensory block; maximum number of blocked segments; duration of sensory block at L3; time to onset of complete motor block; and duration until complete motor block recovery. Vital signs and any adverse effects related to spinal anesthesia were also recorded. No significant differences were found between the two groups: time to onset of sensory block at L3 in group A vs B (2.1 +/- 9.6 vs 1.7 +/- 7.3 minutes), maximum cephalad spread [T4-5 (C3-T11) vs T4 (C3-T8)], maximum number of blocked segments (18.0 +/- 3.4 vs 19.8 +/- 3.7), time to maximum sensory block (34.0 +/- 22.9 vs 26.8 +/- 17.9 minutes), duration of sensory block at L3 (251.2 +/- 34.7 vs 277.3 +/- 51.1 minutes), time to onset of complete motor block (13.4 +/- 6.4 vs 10.3 +/- 3.4 minutes), and time for complete recovery from motor block (264 +/- 52.1 vs 292.5 +/- 64.5 minutes). No significant differences in global hemodynamic changes were found during and after the operation. While shivering was more frequent in group B during the operation, the difference was not significant. Otherwise, there were no differences in adverse effects during and after surgery. We conclude that both doses of 0.75% glucose-free ropivacaine, 26.25 mg (3.5 mL) and 33.75 mg (4.5 mL), have the same efficacy and safety in Chinese patients undergoing spinal anesthesia for lower limb and lower abdominal surgery.