Effects of perineural administration of Dexmedetomidine in combination with Bupivacaine in a femoral-sciatic nerve block

Background: In few studies, Dexmedetomidine was used an adjuvant to local anesthetics in peripheral nerve blocks. Aim: This study was aimed to examine the effect of adding Dexmedetomidine to Bupivacaine 0.5% during the femoral sciatic nerve blocks and to evaluate its effect in prolonging post-operative analgesia. Materials and methods: This was a prospective, double blinded, randomized study which consisted of 80 patients, Patients were randomly allocated into two groups (40patients each): In group BD, (Bupivacaine-Dexmedetomidine hydrochloride), one mL, containing 100 μg, was added to 39 mL of Bupivacaine 0.5%. In group B; 1 mL of normal saline was added to the same volume of Bupivacaine 0.5%. Results: There were no statistically differences between the two groups in demographic data and surgical characteristics. The onset time of sensory block, motor block and surgical anesthesia time were significantly shorter in group BD when compared to group B. The durations of sensory block, motor block and analgesia were longer in BD group when compared to group B. Systolic arterial pressure (SAP) and heart rate were significantly lower in group BD when compared to group B from 10 to 90minutes after initiation of block (P<0.05), diastolic arterial pressure was similarly lower in group BD at 45, 60, and 90 minutes following initiation of block. Conclusion: This study showed that a prolonged duration of analgesia was associated with addition of Dexmedetomidine 100μg to bupivacaine 0.5% during US-guided combined femoral and sciatic block for below knee surgery and is also associated with significant bradycardia requiring treatment.