Ultrasound Guided Femoral Nerve Block to Provide Analgesia for Positioning Patients with Femur Fracture Before Subarachnoid Block: Comparison with Intravenous Fentanyl

Abstract

Background Positioning patients with fractured femur for subarachnoid block is painful. Intravenous analgesics or peripheral nerve block like femoral nerve block or fascia iliaca compartment block are some of the available techniques to reduce pain. We compared the efficacy of femoral nerve block and intravenous fentanyl in providing effective analgesia before positioning for subarachnoid block. Objective This study was designed to compare between ultrasound guided femoral nerve block with lignocaine and intravenous fentanyl in providing effective analgesia before positioning patient with femur fracture in sitting position for subarachnoid block. Method Forty patients undergoing surgery for femur fracture were randomized to either femoral nerve block (FNB) or intravenous fentanyl (IVF) group. Group FNB (n=20) received 20 ml of 2% lignocaine around femoral nerve under ultrasound guidance. IVF group (n=20) received 2 mc/kg of fentanyl intravenously. Pain score on effected limb was assessed after five minutes. If VAS was ≤ 4, the patient was positioned in sitting for subarachnoid block. On failure to achieve this with the above treatment, intravenous fentanyl 0.5 mc/kg was administered and repeated as necessary before positioning. VAS during positioning was documented and compared between the two groups. Similarly, secondary outcomes of the intervention: quality of patient position, rescue analgesia and duration of the procedure were also compared. Data were subjected to Mann Whitney U-test and chi-square test. Level of significance was set at 0.05. Result FNB group had significantly less VAS scores (median) than IVF group :2 vs 3; p=0.037) during positioning for spinal anaesthesia. Procedure time (median) for spinal anaesthesia was also significantly less in FNB than in IVA group (10 vs 12 min; p=0.033) Conclusion Ultrasound guided femoral nerve block was more effective than intravenous fentanyl for reducing pain in patients with proximal femur fracture before spinal anaesthesia.