High thoracic epidural sufentanil with bupivacaine: continuous infusion of high volume versus low volume

The purpose of the study was to investigate whether continuous infusion of a high volume of a sufentanil/bupivacaine mixture at a high thoracic level improves the analgesic effect of the mixture, compared with a dose-equivalent continuous low-volume infusion. In a prospective, observer-blind study, 60 patients scheduled for thoracic surgery received a thoracic epidural catheter for 3 days. The patients were randomly assigned by lot to one of two groups: a low-volume (LV) group (bupivacaine 0.75% with sufentanil 4 micrograms/mL, 1.0-1.3 mL/h), or a high-volume (HV) group (bupivacaine 0.125% with sufentanil 0.7 microgram/mL, 6-8 mL/h). On the first postoperative day significantly more patients in the LV group needed one or more epidural bolus injections because they experienced pain at rest (P < 0.05). On the second and third postoperative days there were no differences in bolus injections. Significantly more patients in the HV group did not require an extra epidural bolus injection (P < 0.05). There were no differences in the number of patients experiencing pain at exercise or in the incidence of side effects. A difference was found between both groups in the mean preoperative PaCO2 value (P < 0.05) and also for the PaCO2 values on Day 1 versus the preoperative values within the group (P < 0.05). On the first postoperative day the analgesic effects of a sufentanil/bupivacaine mixture at a high thoracic epidural level can be improved when injected at a continuous high-volume rate compared with a dose-equivalent continuous low-volume rate. This is true for pain at rest; for pain at exercise, there were no differences.