Postoperative analgesia by continuous extradural infusion of ropivacaine after upper abdominal surgery

Ropivacaine is a new local anaesthetic with advantages that suggest an important role in the provision of postoperative analgesia. The main aim of this study was to investigate the dose-response relationship of extradural infusion of ropivacaine. We studied 36 ASA I-III patients undergoing upper abdominal surgery during general anaesthesia and extradural block (catheter insertion at T6-9) using 0.5% ropivacaine in a randomized, double-blind study. After surgery nine patients each received an extradural infusion of either ropivacaine 0.1%, 0.2%, 0.3% or saline at a rate of 10 ml h(-1) for 21 h. All patients had access to i.v, morphine via a PCA device. The ropivacaine groups consumed significantly less morphine over the 21-h infusion period than the saline group (medians: saline 75 mg; 0.1% ropivacaine 32 mg; 0.2% ropivacaine 39 mg; 0.3% ropivacaine 13 mg) (P < 0.05). Pain (VAS scores) at rest was significantly lower in all ropivacaine groups than in the saline group after 4 h of infusion (medians: saline 45 mm; 0.1% ropivacaine 15 mm; 0.2% ropivacaine 12 mm; 0.3% ropivacaine 0 mm). Pain on coughing was significantly less in all ropivacaine groups than in the saline group after 4 h infusion (medians: saline 67 mm; 0.1% ropivacaine 44 mm; 0.2% ropivacaine 33 mm; 0.3% ropivacaine 0 mm) and for 0.2% and 0.3% ropivacaine at later times. Motor block was negligible throughout the infusion. Patient satisfaction was higher in the 0.2% and 0.3% ropivacaine groups than in the two other groups.