Fentanyl does not improve the nerve block characteristics of axillary brachial plexus anaesthesia performed with ropivacaine

Background: The aim of this prospective, randomized, double-blind study was to evaluate the effects of adding 1 mug.kg(-1) fentanyl to ropivacaine 7.5 mg.ml(-1) for axillary brachial plexus anaesthesia. Methods: With Ethics Committee approval and written consent, 30 ASA physica l status I-LI in-patients, scheduled for orthopaedic hand procedures were r andomly allocated to receive axillary brachial plexus block with 20 mi of e ither ropivacaine 7.5 mg.ml(-1) (n=15) or ropivacaine 7.5 mg.ml(-1)+1 mug.m l(-1) fentanyl (n=15). Nerve blocks were placed using a nerve stimulator wi th the multiple injection technique. A blinded observer recorded the time t o onset of surgical block (loss of pinprick sensation in the innervation ar eas of the hand (C-6-C-8) With concomitant inability to flex the wrist agai nst gravity and move the fingers when squeezing the hand) and first request for pain medication after surgery. Results: No differences in demography, degree of sedation or peripheral oxy gen saturation were observed between the two groups. Median (range) time re quired to achieve readiness for surgery was 15 min (5-36 min) with ropivaca ine alone and 15 min (5-40 min) with the ropivacaine-fentanyl mixture. No d ifferences in the intraoperative quality of nerve block were reported betwe en the two groups. Four patients receiving ropivacaine plain and two patien ts receiving the ropivacaine-fentanyl mixture did not require analgesics du ring the first 24 h after surgery (P=0.62). The degree of pain experienced at first analgesic request in those patients asking for pain medication, as well as median consumption of postoperative analgesics, were similar in th e two soups. First postoperative analgesic request was made at 11 h (25th-7 5th percentiles: 9.1-14 h) in patients receiving ropivacaine alone and at 1 1.8 h (25th-75th percentiles: 9.8-15 h) in patients receiving the ropivacai ne-fentanyl mixture (P=0.99). Conclusion: The addition of fentanyl 1 mug.ml(-1) to ropivacaine 7.5 mg.ml( -1) does not improve the nerve block characteristics of axillary brachial p lexus anaesthesia for orthopaedic procedures involving the hand.