Ultrasound-Guided Femoro-Sciatic Nerve Block Using Dexmedetomidine and Bupivacaine Versus Fentanyl and Bupivacaine for Below-Knee Surgery

In the literature, Effective postoperative analgesia for below-knee surgery is crucial for recovery. While opioids like fentanyl are common adjuvants in regional anesthesia, they carry inherent risks. Dexmedetomidine, a non-opioid alternative, may offer superior benefits. This study was conducted to compare dexmedetomidine and fentanyl as adjuvants to bupivacaine in FSNB for below-knee surgery. Methods: Methods A prospective, randomized, double-blind study was conducted at the Kobry El-Koba Military Hospital, including 56 patients scheduled for elective below-knee surgery. Participants were allocated to receive FSNB with either 0.25% bupivacaine plus 1 µg/kg dexmedetomidine (Group D) or 0.25% bupivacaine plus 1 µg/kg fentanyl (Group F). The primary outcome was postoperative pain on the Numerical Rating Scale (NRS). Secondary outcomes included block onset/duration, opioid consumption, and hemodynamics. Results: 2 Demographics were comparable. The onset of sensory block was faster in Group D (23.9±7.8 vs. 28.8±6.8 min, p=0.014). Durations of sensory block (492.4±188 vs. 371.2±161 min, p=0.012), motor block (560.4±221 vs. 421.2±156 min, p=0.009), and analgesia (735.5±315 vs. 489.6±207 min, p=0.001) were significantly longer in Group D. NRS scores and rescue analgesic demand were significantly lower in Group D at 12, 18, and 24 hours. Conclusion: Dexmedetomidine is a superior adjuvant to bupivacaine in FSNB compared to fentanyl, providing faster sensory onset, prolonged analgesia, and reduced opioid consumption.