Ropivacaine 1 mg x ml(-1) does not decrease the need for epidural fentanyl after hip replacement surgery.

Background: Ropivacaine is a new long-acting local anesthetic. Laboratory trials have demonstrated a synergistic analgesic effect between intrathecal opioids and local anesthetics. We tested the hypothesis that addition of ropivacaine 1 mg x ml(-1) to epidural fentanyl (10 microg x ml(-1)) postoperatively decreases the need for fentanyl, improves the quality of analgesia and decreases the side-effects of fentanyl.

Methods: Forty patients were enrolled in this double-blind, randomized study to receive either fentanyl 10 microg x ml(-1) (group F) alone or fentanyl combined with ropivacaine 1 mg x ml(-1) (group R) for 20 h as an epidural infusion at TH12-L1 or L1-L2 for analgesia after hip replacement surgery. The patients were free to use a patient-controlled epidural analgesia device, which was programmed to infuse 3 ml of the study medication hourly and to allow a 3-ml bolus when needed (maximal hourly dose of fentanyl was 150 microg). The consumption of medication, visual pain scores at rest and on movement, hemodynamic and respiratory parameters, motor and sensory block, nausea, pruritus and sedation were recorded.

Results: There were no significant differences between the groups in the total mean fentanyl consumption (1.10+/-0.18 mg in group F, 1.08+/-0.31 mg in group R, 95% CI: -0.14 to 0.19, P = 0.774). The pain scores were similar at rest (median scores < or = 1) and on movement (median scores < or = 3). The adverse effects were similar and of a minor nature, consisting mostly of pruritus and nausea.

Conclusion: Addition of ropivacaine 1 mg x ml(-1) to epidural fentanyl 10 microg x ml(-1) did not significantly decrease the requirement for fentanyl administered for pain relief after hip replacement surgery.