Epidural ropivacaine with fentanyl following major gynaecological surgery: the effect of volume and concentration on pain relief and motor impairment

In a prospective, randomized, double-blind study, 40 patients undergoing gynaecological oncology surgery received either 0.1% ropivacaine with fentanyl I mu g ml(-1) or 0.2% ropivacaine with fentanyl 2 mu g ml(-1). A PCEA pump was set to deliver ropivacaine 8 mg with fentanyl 8 mu g with each successful demand and a lockout period of 15 min without background infusion. Patients were observed for rest and activity pain VAS, side effect incidence, peak expiratory flow rate (PEFR), leg strength, sensory block to cold and pinprick, and PCEA usage into the second postoperative day. Passive and active pain scores for both groups were both satisfactory and comparable for the duration of the study. There were no differences between groups with regard to side effects. There was a 24% increase in total drug used in the high-concentration/ low-volume group (P<0.05). The study demonstrated that PCEA ropivacaine with fentanyl is an effective means of postoperative analgesia for this patient population. Reduced drug consumption with high-volume/low-concentration solution confirms similar findings by other investigators using alternate local anaesthetic agents, and suggests that the therapeutic ratio of ropivacaine is widened if a low-concentration/high-volume solution is used.