Spinal anesthesia for urologic surgery in elderly patients is preferred. The addition of opioids to local anesthetics reduces the side effects of spinal anesthesia. This study examined the effects of intrathecal fentanyl 10 µg and 20 µg when administered with hyperbaric 0.5% bupivacaine to elderly patients undergoing urologic surgery.

Forty-five elderly patients undergoing urologic surgery were randomized into the following three groups: group 1, bupivacaine 7.5 mg; group 2, bupivacaine 5 mg + fentanyl 10 µg; and group 3, bupivacanie 5 mg + fentanyl 20 µg. The total volume of intrathecally injected was adjusted to 1.5 ml with sterile normal saline. Spinal anesthesia was administered with a 25 G Quincke needle at the L3-4 or L4-5 interspace in the lateral position. The neural block was assessed using a pinprick test and the Bromage scale.

There were no significant differences in the onset time of the T10 sensory block, peak level of the sensory block, and onset time of the peak level. The duration of the sensory block was significantly shorter in group 2 than in group 1 (P = 0.017). The duration of the motor block was longer in group 1 than in groups 2 and 3 (P = 0.016, P = 0.04). Pruritus was observed more often in group 3 (37.5%) and shivering was more common in group 1 (P = 0.005).

The addition of fentanyl 10 µg and 20 µg to bupivacaine 5 mg provides adequate anesthesia for elderly patients undergoing urologic surgery with fewer side effects, and fentanyl 10 µg is recommended as outpatient anesthesia.