Background and objective: This prospective, randomized, double-blind study was conducted to evaluate the onset time and duration of sciatic nerve block produced with 0.5% levobupivacaine, 0.75% levobupivacaine and 0.75% ropivacaine.
Methods: Forty-five healthy patients undergoing hallux valgus repair were randomly allocated to receive sciatic nerve block with levobupivacaine 0.5% (n = 15), levobupivacaine 0.75% (n = 15) or ropivacaine 0.75% 20 mL (n = 15). A femoral nerve block was also performed with mepivacaine 2% 15 mL to cover pain related to the thigh tourniquet. A blinded observer recorded the onset time and duration of sciatic nerve block.
Results: The median (range) onset time was 5 (5–40) min with 0.75% levobupivacaine, 30 (5–60) min with 0.5% levobupivacaine and 20 (5–50) min with 0.75% ropivacaine (P = 0.02 and P = 0.12, respectively). Mean (25–75 percentiles) first request for pain medication occurred after 13 (11–14) h with 0.75% ropivacaine, 18 (15–19) h with 0.75% levobupivacaine and 16 (13–20) h with 0.5% levobupivacaine (P = 0.002 and P = 0.002, respectively). Rescue tramadol after surgery was required by three patients in the 0.75% levobupivacaine group, eight patients in the 0.5% levobupivacaine group and nine patients in the 0.75% ropivacaine group (P = 0.05).
Conclusions: We conclude that 0.75% levobupivacaine provides a shorter onset time than 0.5% levobupivacaine and a longer duration of postoperative analgesia than both 0.5% levobupivacaine and 0.75% ropivacaine with reduced need for rescue analgesia after surgery.