Regression of sensory and motor blockade, and analgesia during continuous epidural infusion of ropivacaine and fentanyl in comparison with other local anesthetics

Background: To compare the regression of sensory and motor blockade, and the analgesia during continuous epidural infusion between ropivacaine and other local anesthetics. Design. Two studies were conducted. Study 1: Eighty patients were scheduled for orthopedic procedures of the lower extremity under lumbar epidural anesthesia. Following the operation, continuous infusion of a randomized solution (0.2% ropivacaine, 0.125% bupivacaine, 0.5% lidocaine, or 0.2% ropivacaine with 2.5 mu g/mL fentanyl) was commenced at a rate of 6 mL/h. The regression of sensory and motor blockade were compared among the groups. Study 2: After gynecologic abdominal surgery, 39 patients were randomized to one of the three epidural infusion groups: 0.2% ropivacaine, 0.125% bupivacaine, or 0.2% ropivacaine with 2.5 mu g/mL fentanyl at a rate of 6 mL/h with an additional bolus injection of 3 mL, which can be used when patients have pain. Visual analog scale (VAS) was compared among the groups. Results. Study 1: The level of sensory blockade in all the groups appeared to decrease progressively. However, the regression of sensory blockade was significantly prolonged in patients treated with ropivacaine. The addition of fentanyl to ropivacaine augmented this prolonged analgesic effect. Study 2: VAS after the bolus in the ropivacaine and the ropivacaine + fentanyl groups were significantly lower than that in the bupivacaine group. Patients in the ropivacaine + fentanyl group required significantly fewer supplemental bolus injections. Conclusions. Continuous epidural infusion of ropivacaine may induce a slower regression of sensory blockade compared with bupivacaine and lidocaine. The addition of fentanyl to ropivacaine can enhance this prolonged analgesic effect with little effect on motor blockade. Epidural infusion of ropivacaine with fentanyl provides effective pain relief, possibly because of the maintenance of sensory blockade by ropivacaine and fentanyl.