Epidural fentanyl speeds the onset of sensory block during epidural lidocaine anesthesia

Background and Objectives: Shortening the onset time of sensory block is a practical goal to improve the quality of epidural anesthesia. The addition of fentanyl to a local anesthetic solution is widely used during epidural a nesthesia. This randomized double-blind study examined the onset time of se nsory block during epidural lidocaine anesthesia with and without added fen tanyl to the epidural solution. Methods: Thirty-six young male patients undergoing knee arthroscopy were ra ndomly allocated into 3 groups of 12 patients each: epidural fentanyl (EF, epidural administration of 17 mL of 2% lidocaine plus 100 mug fentanyl and followed by intravenous (IV) injection of 2 mL of normal saline); IV fentan yl (IF, epidural administration of 17 mL of 2% lidocaine plus 2 mL of norma l saline and followed by IV injection of 100 mug of fentanyl); and control (C, epidural administration of 17 mL of 2% lidocaine plus 2 mL of normal sa line and followed by IV injection of 2 mL of normal saline). The sensory bl ock was assessed by pinprick method. The hemodynamic changes, postepidural shivering and side effects of epidural fentanyl were also recorded. Results: There was no difference in the distribution of age, weight, and he ight among the 3 groups. The onset time of sensory block up to T-10 dermato me was significantly more rapid in the EF group (8.3 +/- 3.7 minutes) than that of the IF group (13.1 +/- 4.2 minutes, P <.05) or C group (14.2 +/- 5. 4 minutes, P <.05). The upper level of sensory block was also significantly higher in the EF group. Although the incidence of shivering was lower in t he EF group, this did not reach statistical significance. Postepidural arte rial blood pressures and heart rates were no different among the 3 groups. No nausea, vomiting, pruritus, respiratory depression, urinary retention, o r hypotension were observed in any patients. Conclusion: Epidural injection of the mixture of 100 mug fentanyl and 2% li docaine solution accelerated the onset of sensory block during epidural lid ocaine anesthesia without increased side effects.