Epidural fentanyl speeds the onset of sensory and motor blocks during epidural ropivacaine anesthesia

In this study we examined the onset times of sensory and motor block during epidural ropivacaine anesthesia with and without the addition of fentanyl to the epidural solution. Forty-five young male patients undergoing knee arthroscopic surgery were randomly allocated into 3 groups of 15 patients each: epidural fentanyl (EF; epidural administration of 15 mL of 1% ropivacaine plus 100 mug fentanyl followed by IV injection of 2 mL of normal saline); IV fentanyl (IF; epidural administration of 15 mL of 1% ropivacaine plus 2 mL of normal saline followed by IV injection of 100 mug fentanyl); and control (C; epidural administration of 15 mL of 1% ropivacaine plus 2 mL of normal saline followed by IV injection of 2 mL of normal saline). The sensory and motor blocks were assessed by pinprick and modified Bromage scale, respectively. The hemodynamic changes, postepidural shivering, and side effects of epidural fentanyl were also recorded. There was no difference in the distribution of age, weight, and height among the 3 groups. The onset time of sensory block to the T10 dermatome was significantly more rapid in the EF group (13.0 +/- 3.0 min) than in the IF group (16.2 +/- 3.5 min, P < 0.05) or C group (17.7 +/- 3.6 min, P < 0.05). The onset times of motor block up to Bromage scale 1 and 2 were significantly more rapid in the EF group (11.9 +/- 4.6 and 24.4 +/- 5.9 min) than in the IF group (16.9 +/- 4.7 and 30.8 +/- 5.6 min, P < 0.05) or C group (18.3 +/- 4.9 and 32.7 +/- 5.7 min, P < 0.05). There was no difference in the incidence of shivering among the three groups. Pruritus was observed in three patients of the EF group and one patient of the IF group. No nausea, vomiting, respiratory depression, urinary retention, or hypotension was observed in any patient. We conclude that epidural administration of the mixture of 100 mug fentanyl and 1% ropivacaine solution accelerated the onset of sensory and motor blocks during epidural ropivacaine anesthesia without significant fentanyl-related side effects.