Thoracic epidural bupivacaine plus sufentanil: high concentration/low volume versus low concentration/high volume

To compare the postoperative analgesic and side effects of a continuous epidural infusion of bupivacaine with sufentanil: high concentration/low volume versus low concentration/high volume.

In a prospective study, 30 patients scheduled for thoracic surgery had a thoracic epidural catheter inserted. Postoperative analgesia was provided by a continuous epidural infusion for 3 days. The patients were randomly divided into two groups: the low volume (LV) group (1.5 to 2 mL per hour of a combination of bupivacaine 0.5% with sufentanil 4 micrograms.mL-1) and the high volume (HV) group (6 to 8 mL per hour of a combination of bupivacaine 0.125% with sufentanil 1 microgram.mL-1).

The visual analogue scales were not different at rest or with exercise on days 1, 2, or 3. Supplemental analgesia by epidural catheter was necessary in half the patients in both groups. In two patients in the HV group and five patients in the LV group, a PaCO2 greater than mm Hg (7 kPa) was observed the first postoperative hour. Only on day 1 was the mean PaCO2 significantly increased in both groups (5.9 mm Hg [0.7] kPa in the LV group, and 6.0 mm Hg [0.4] kPa in the HV group) compared to the mean preoperative PaCO2 (5.1 mm Hg [0.5] kPa and 4.7 mm Hg [0.6] kPa). Between the groups there was no significant difference in PaCO2 at any time.

With the thoracic epidural administration of bupivacaine and sufentanil for postoperative analgesia, the total dose is more important than the concentration or the volume of the solution.