Femoral nerve block versus fentanyl: Analgesia for positioning patients with fractured femur

Arissara Iamaroon, Manee Raksakietisak, Pathom Halilamien, Jitaporn Hongsawad, Kwankamol Boonsararuxsapong

Department of Anesthesiology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand

Purpose: Fracture of femur is a painful bone injury, worsened by any movement. This prospective study was performed to compare the analgesic effects of femoral nerve block (FNB) with intravenous (IV) fentanyl prior to positioning patients with fractured femur for spinal block.

Patients and methods: Sixty-four ASA I–III patients aged 18–80 years undergoing surgery for femur fracture were randomized into two groups. Fifteen minutes before spinal block, the FNB group received nerve stimulator-assisted FNB with a mixture of 20 mL bupivacaine 0.5% and 10 mL normal saline 0.9%, and the fentanyl group received two doses of IV fentanyl 0.5 μg/kg with a five-minute interval between doses. Numeric rating pain scores were compared. During positioning, fentanyl in 0.5 μg/kg increments was given every five minutes until pain scores were ≤4.

Results: There were no statistically significant differences between the groups according to pain scores, need for additional fentanyl, and satisfaction with positioning before spinal block.

Conclusion: We were unable to demonstrate a benefit of FNB over IV fentanyl for patient positioning before spinal block. However, FNB can provide postoperative pain relief, whereas side effects of fentanyl must be considered, and analgesic dosing should be titrated based on pain scores. A multimodal approach (FNB + IV fentanyl) may be a possible option.

Keywords: femoral nerve block, bupivacaine, fentanyl, pain on positioning