Epidural fentanyl improves the onset and spread of epidural mepivacaine analgesia.

PURPOSE

To determine the extent of enhanced blockade by the combined use of epidural fentanyl and mepivacaine. We compared the onset of hypoalgesia, analgesia and the threshold of pressure pain.

METHODS

Thirty patients were randomly divided into three groups. The fentanyl group received 10 ml saline containing 0.1 mg fentanyl, mepivacaine group received 10 ml mepivacaine 1% and a mixed group received 10 ml mepivacaine 1% with 0.1 mg fentanyl. All solutions, without epinephrine, were injected through an epidural catheter at T5-6 to T6-7. The change in sensation, loss of pin-prick and pain threshold sensation, measured by pressure algometer, were assessed at 2.5-min intervals for 15 min at the T4 dermatome. Spread of analgesia was determined at 15 min.

RESULTS

Loss of pinprick was more rapid in the mixed, 11.0 +/- 2.7 (SD) min, than in the mepivacaine group, 15.0 +/- 2.9 min, (P < 0.05), although there was no difference in change of sensation. Pressure pain threshold increased with time in the mepivacaine (P < 0.05) and mixed (P < 0.05) groups. It was higher in the mixed than in the fentanyl and mepivacaine groups at 5, 7.5 and 10 min (P < 0.05). The lower level of analgesia was lower in the mixed than in the mepivacaine groups (P < 0.05). Blood pressure was unchanged in the three groups, but heart rate decreased at 7.5, 10, 12.5, and 15 min in the mepivacaine and mixed groups (P < 0.05).

CONCLUSIONS

The addition of fentanyl to mepivacaine accelerates the onset of analgesia and enhances the analgesic effect of epidural block.