Spinal anaesthesia: comparison of plain ropivacaine 5 mg ml(-1) with bupivacaine 5 mg ml(-1) for major orthopaedic surgery

Background. Ropivacaine provides effective spinal anaesthesiafor total hip arthroplasty. This study was designed to comparethe efficacy and safety of plain ropivacaine with plain bupivacainefor spinal anaesthesia in patients undergoing total hip arthroplasty. Methods. Sixty-six patients, ASA I or II, were randomized toreceive an intrathecal injection of one of two local anaestheticsolutions. Group R (n=32) received 3.5 ml of ropivacaine 5 mgml^–1 (17.5 mg). Group B (n=34) received 3.5 ml of bupivacaine5 mg ml^–1 (17.5 mg). The onset and duration of sensoryblock at dermatome level T10, maximum upper and lower spreadof sensory block and the onset, intensity and duration of motorblock were recorded, as were safety data. Results. Onset of motor and sensory block was rapid with nosignificant differences between the two groups. The median timeof onset of sensory block at the T10 dermatome was 2 min (range2–5 min) in Group R and 2 min in Group B (range 2–9min). The median duration of sensory block at the T10 dermatomewas 3.0 h (range 1.5–4.6 h) in Group R and 3.5 h (2.7–5.2h) in Group B (P<0.0001). The median duration of completemotor block (modified Bromage Scale 3) was significantly shorterin the ropivacaine group compared with the bupivacaine group(2.1 vs 3.9 h, P<0.001). Conclusions. Intrathecal administration of either 17.5 mg plainropivacaine or 17.5 mg plain bupivacaine was well toleratedand an adequate block for total hip arthroplasty was achievedin all patients. A more rapid postoperative recovery of sensoryand motor function was seen in Group R compared with Group B. Br J Anaesth 2002; 89: 702–6